Principles and Limitations of Converting Vibration to Electricity with Piezoelectric Devices The vibration energy we encounter in everyday life is often dissipated and lost. However, with piezoelectric elements , it is possible to convert such vibrations into electricity to power electronic devices. This article explores the working principles of piezoelectric devices, their applications, and their real-world limitations. Principle of Piezoelectric Devices Piezoelectric devices use the phenomenon called the piezoelectric effect , in which a voltage is generated when a material with a specific crystal structure is subjected to mechanical force (compression, bending, vibration, etc.). Conversely, when voltage is applied, the material deforms—this is known as the inverse piezoelectric effect . In energy harvesting, the direct effect is used to convert vibration into electrical energy. Electricity Conversion Process External vibration or pressure is applied to the piezoelectric d...

During peak summer heat, most people assume ice cream sales will soar. But in 2024, Korea’s ice cream market experienced a dramatic 35% drop in sales . This isn’t just a shift in consumer preferences — it’s a result of supply chain and distribution failures . This blog takes a closer look at how broken logistics and shelving strategies are keeping ice cream out of consumers' hands at the very moment it's most in demand. 1. Cold Chain Logistics: The Invisible Weakness Ice cream depends entirely on consistent freezing from factory to shelf . When summer heat intensifies, cold trucks are overbooked and store freezers exceed capacity . As a result, many retailers have reduced or suspended restocking ice cream products altogether. 2. Inflexible Distribution Systems Most ice cream supply chains operate on fixed delivery schedules, leaving little room to respond to temperature shifts, local demand, or real-time sales data . This leads to out-of-stock situations in some regi...

When your smart key’s battery is dead or the key is lost, starting your vehicle can feel impossible. But don’t worry—most smart key-enabled vehicles are equipped with emergency start features . This post outlines how to start your car without a smart key and offers tips for staying calm in emergencies. 1. Common Reasons Your Smart Key May Not Work Dead battery: The internal CR2032 battery in the smart key has expired. Wireless interference: RF interference blocks the vehicle from receiving the key’s signal. Moisture or impact: Internal circuit damage inside the smart key. Loss or theft: You don’t have the physical key in possession. 2. Emergency Methods to Start Your Vehicle While exact steps vary by make and model, most vehicles support one of these emergency authentication methods . 1) Hold the Smart Key Against the Start Button Place the smart key directly against the engine Start/Stop button. With the key pressed to the button, step on th...

1. Where Does the Name Jjamppong Come From? The term “jjamppong” originated from the Japanese word “ちゃんぽん (Champon),” which means mixing various ingredients. After being introduced to Korea, it transformed into a unique spicy soup noodle dish that perfectly suits Korean tastes. 2. A Style Not Found in China While mainland China does offer seafood soup noodles and broth-based noodles, the spicy red version of jjamppong found in Korea doesn’t exist there. Korean jjamppong is made by stir-frying seafood and vegetables at high heat, then adding a spicy broth—completely different in flavor and technique from Chinese versions. 3. How Korean-Chinese Cuisine Was Born Starting in the late 19th century, Chinese immigrants settled in areas like Incheon and Busan. They began adapting their native dishes to suit Korean palates. Jjamppong is a prime example of this cultural fusion—combining Japanese champon, Chinese soup noodles, and the beloved Korean spiciness. 4. Other Dishes...

Mornings are always rushed—but that doesn't mean you have to sacrifice your health. What if you had a super simple salad that takes just 3 minutes to make? Here’s how to start your day with a quick, energizing salad even when you're short on time. 1. Prep the Night Before: The Key to Success Vegetables: Wash and dry romaine, spinach, cucumbers, etc., and store them sealed in the fridge Protein: Pre-cook chicken breast, boiled eggs, or chickpeas and refrigerate Dressing: Mix in advance and keep in a sealed jar (lasts 3–5 days) 2. Your 3-Minute Morning Routine Grab the ingredients, plate the veggies and protein, drizzle dressing, toss—and done. Truly just 3 minutes , no chopping, no cooking, no fuss. 3. Sample Salad Combos You Can Make in 3 Minutes ① Boiled Egg + Mixed Greens + Nuts Dressing: Olive oil + balsamic vinegar Highlights: Protein plus healthy fats in one bowl ② Chicken Breast + Romaine + Cherry Tomatoes Dressing: Plain yogu...

Can You Use Just Any Pot on an Induction Cooktop? Induction cooktops heat cookware directly through electromagnetic induction, which means not all pots are compatible . Only pots that respond to magnetic fields will work. Luckily, there’s a simple trick anyone can do: the magnet test . 1. Why Does Cookware Material Matter? Induction cooktops use the principle of electromagnetic induction . A coil underneath the surface generates a magnetic field that creates eddy currents in the cookware, which are then converted to heat through resistance. This means the cookware must be made of magnetic material to generate heat. 2. The Magnet Test: Easiest Way to Check Compatibility Place a magnet on the bottom of the pot. - If it sticks firmly → Compatible with induction - If it doesn’t stick → Not compatible Even stainless steel may not work depending on the type. Aluminum, copper, glass, and ceramic cookware are generally not compatible unless they have a special...

Capacitors , commonly referred to as condensers , began in the 18th century through electrostatic experiments and have since become essential components in high-performance electronic devices . In this post, we will explore the origin, inventors, technological evolution, and modern applications of capacitors.     1. Origins and Early Experiments In 1745 , Ewald Georg von Kleist from Germany conducted a static electricity experiment using a glass jar filled with water and wrapped in metal. This device was the Leyden Jar , the prototype of the capacitor. A similar experiment was conducted by Pieter van Musschenbroek of the Netherlands, which helped formalize its function. 2. The Term “Condenser” Alessandro Volta expanded the principle of the Leyden Jar and described the device as one that "condenses electricity." This led to the term condenser being widely used in Europe. To this day, countries like Japan and South Korea commonly use this term. ...

With the introduction of CBDC (Central Bank Digital Currency), concerns about surveillance of personal transactions are rising. This post explores how to prevent "monitored consumption" and protect user privacy in the age of digital currency.     📷 Visual: CBDC Security and Privacy  Balancing Digital Wallets and Privacy Source: Freepik (royalty-free) 1. How Well Can Personal Data Be Protected? Since CBDC allows central banks to access transaction data, privacy concerns are inevitable. However, the following technologies can address this: Pseudonymization: Users are identified with anonymous IDs; real names are only accessed when necessary Tiered Privacy: Small payments can remain anonymous; larger ones require identification     2. The Role of Zero-Knowledge Proof (ZKP) ZKP is a cryptographic method that proves a transaction occurred without revealing its contents. This allows you to validate spendin...

When red rashes, itching, or swelling appear after sun exposure, many people quickly assume they have a sun allergy . However, several other skin conditions mimic similar symptoms, leading to frequent misdiagnoses. Properly identifying the exact cause is essential for receiving the right treatment and preventing long-term complications.     Why Sun Allergy Is Easily Confused Sun allergy (also called photosensitivity) typically causes redness, burning, itching, and raised rashes, especially on areas exposed to sunlight like the neck, arms, and face. However, the same regions are affected by many other conditions with overlapping symptoms. This is why correct diagnosis is critical. Here Are 5 Conditions Often Misinterpreted as Sun Allergy:     1. Seborrheic Dermatitis Symptoms: Flaky, red skin especially around the nose, scalp, eyebrows, and ears. Key Difference: Not triggered by sunlight. Caused by overactive oil glands and yeast ...

Have you ever experienced red patches, itching, or rashes on sun-exposed areas of your skin? While it might seem like general skin sensitivity, it could actually be a photosensitivity reaction caused by certain medications . This post explains which medications can trigger sun allergies, how to verify them, and what precautions you should take when using them.     What is a Photosensitivity Reaction? Photosensitivity is a skin reaction caused by a drug or chemical when it interacts with UV rays. This can lead to inflammation or immune responses when the substance becomes active under sunlight exposure. Common Medications That Can Trigger Sun Allergy Antibiotics: Tetracyclines, Quinolones, Sulfonamides Diuretics: Hydrochlorothiazide, Furosemide NSAIDs: Ibuprofen, Naproxen, Ketoprofen Antidepressants and Psychiatric drugs: Tricyclics, some SSRIs Antifungals and Chemotherapy agents Hormonal agents including birth control pills Even ...

One of the biggest challenges in DIY battery pack assembly is how to safely and securely connect 18650 cells. Most professionals recommend using a spot welder, but not everyone has one at home. So, is it possible to connect cells safely and effectively without a spot welder? In this post, we’ll explore alternative methods that don’t damage the cells and are suitable for small-scale battery building.     Common Alternatives to Spot Welding If you don’t have access to a spot welder, here are three main alternatives you can consider: Soldering: The traditional method using a soldering iron to attach nickel strips or wires directly to the cell terminals. Clamping: Mechanically pressing nickel strips onto the cell using clips, screws, or springs. Battery Holders: Inserting cells into prebuilt plastic cases that include metal contact terminals. Each method has its pros and cons, and the best choice depends on your application, the number of cell...

Refrigerators are appliances we open and close dozens of times each day. Especially during summer, the door sensor plays a vital role in minimizing cold air loss. Recently, some Samsung refrigerator users have reported an issue where the door is slightly open, but no alarm goes off. Is this just a sensor malfunction? Or is it a more fundamental design flaw? In this post, we’ll examine the causes behind Samsung refrigerator door alert failures, how electronic sensors work, and what consumers can do about it.     What Is an Electronic Door Sensor? Most modern refrigerators now come with an electronic door sensor . This usually involves a magnetic strip on the door and a reed switch inside the body, which detects the magnetic field to determine whether the door is open or closed. This type of sensor is easier to manufacture, more cost-efficient, and compatible with digital signal processing. However, electronic sensors can fail to detect when the door i...

A center finder is an incredibly useful tool for marking the exact center of a circular piece, but if you don’t have one, you can make it yourself! In this post, you’ll learn how to create your own DIY V-shaped center finder with high accuracy using low-cost materials.     1. Basic Idea: The 90-Degree V Frame The heart of a DIY center finder is a right-angle (V-shaped) frame with a guide hole at the apex . When this V frame is aligned to the edge of a circle and a line is drawn through the apex, multiple lines from different angles will intersect at the true center. 2. Materials Needed MDF or plywood (3–5mm thick recommended) Saw or laser cutter Set square or precision triangle Screws or wood glue Pencil or scribe     3. How to Build It Cut two right triangles out of MDF or plywood. Join them to form a perfect 90-degree V-shaped frame. Drill a small hole at the apex where the two arms meet. This is w...

Lithium-ion batteries power our daily devices—smartphones, laptops, electric vehicles, and more. But when you need to store these batteries for months or years, improper storage can lead to performance loss, reduced lifespan, and safety hazards. This guide shares practical tips to help you store lithium-ion batteries for 6 months to 1 year (or longer) while keeping them in great condition.     Ideal Charge Level for Storage Storing batteries at 100% charge or fully discharged (0%) accelerates chemical degradation and reduces lifespan. The best charge level for long-term storage is between 40% and 60%. This reduces internal stress on electrodes and helps prevent deep discharge from natural self-discharge over time. Temperature and Environment High temperatures accelerate electrolyte degradation, while extreme cold reduces chemical activity. The ideal storage environment is a cool, dry place between 10°C and 25°C . Avoid storing batteries in places like car...

When repairing or analyzing a 21V lithium-ion drill battery pack, one of the most critical aspects is checking the MOSFETs on the BMS board. Among them, understanding how to measure the gate voltage and confirm switching status is a key skill for troubleshooting battery issues.     Structure and Role of FETs in a BMS Most BMS (Battery Management System) boards consist of two N-channel MOSFETs: one for charging and one for discharging. In a 5S configuration, the board monitors the voltage of five cells via B1~B5 lines and controls the two MOSFETs accordingly. Charging FET: Controls current entering from the charger to the battery. Discharging FET: Controls current exiting from the battery to the drill or other load.     Where is the Gate Voltage Supplied From? Unlike simple switches, the gate of a MOSFET in a BMS doesn’t receive constant voltage. Instead, the BMS controller IC provides a pulse or a fixed voltage depending o...

If you cook often, you know how frustrating deep knife scars on a cutting board can be. But some boards maintain a fresh, smooth surface even after years of use. The secret? End grain cutting boards. In this post, we'll dive into the science behind how end grain boards protect knives and “heal” themselves after every cut.     1. What Is an End Grain Cutting Board? An end grain cutting board is made by arranging wood so the cut ends—where the growth rings are visible—face upward. It’s like looking down at a tree stump. This is fundamentally different from flat grain or edge grain boards. 2. The Role of Wood Fiber Orientation Wood is made up of vertical cellulose fibers. In flat grain boards, knives cut across these fibers, causing damage. In contrast, end grain boards allow the knife to slide between fibers. These fibers then bounce back, forming a natural self-healing structure that protects both the board and the blade.     3...

We learn the concept of "infinity" in school as if it's something simple. However, when we dig deeper, we discover that it hides surprising truths that go against our everyday logic and intuition. In this post, we’ll explore several paradoxes of infinity that show how strange and fascinating the world of mathematics can be.     1. Gabriel’s Horn: A Shape You Can Fill but Never Paint Gabriel’s Horn is created by rotating the curve y = 1/x (for x ≥ 1) around the x-axis. This shape stretches infinitely far but has a finite volume of π. However, its surface area is infinite. In theory, you could fill it with a finite amount of paint, but you could never paint the entire surface. This paradox perfectly illustrates how mathematical truth can defy human intuition.     2. Hilbert’s Hotel: The Fully Booked Hotel That Always Has Room German mathematician David Hilbert imagined an infinite hotel that is fully occupie...

If your car’s radiator fan is behaving strangely—running nonstop or not turning on at all—one component you should suspect is the thermistor switch . This small part controls when the cooling fan turns on and off based on engine temperature. In this post, we’ll walk you through how to locate, replace, and test a thermistor switch yourself, along with tips, tools, and safety precautions to make it a successful DIY repair.     1. When Should You Replace the Thermistor Switch? Radiator fan keeps running after engine shutoff Fan turns on even when the engine is cold Fan does not turn on, causing engine overheating Engine warning light or cooling fan control DTCs (Diagnostic Trouble Codes) 2. Where to Find the Thermistor Switch The switch location varies by vehicle, but it is commonly found in: Lower or side section of the radiator Near the thermostat housing On or around the cylinder head     3. Tools and Mater...

Launching a new blog and not seeing your posts show up in Google search results can be discouraging. Even when Search Console shows your URLs as indexed, you might notice that there's barely any traffic or impressions. This is where the concept of the "sandbox effect" comes into play.     What Is the Sandbox Effect? The term "sandbox" originally comes from software development and cybersecurity. It refers to a controlled environment where systems can be tested without affecting the real world. In the SEO world, it refers to an unofficial period where Google observes new websites before allowing them to rank competitively. Although Google has never officially confirmed the existence of a sandbox, many SEO experts and webmasters have observed that new domains often struggle to gain visibility for several weeks or months. Typical Characteristics of the Sandbox Period Pages are indexed but rank very low in SERPs. ...

Have you ever wondered why sounds seem to travel more quickly underwater? Submarines can detect sounds from other vessels kilometers away almost instantly. In contrast, the same distance in air results in delayed and weaker sound transmission. This difference boils down to two key physical properties: compressibility and density .     What is Sound? – The Propagation of Vibrations Sound is the transmission of vibrations through a medium. When particles in a substance vibrate, they bump into neighboring particles and pass along the energy. Two primary factors determine the speed of this transmission: Bulk Modulus : Indicates how quickly pressure is transmitted through the medium. Density : Measures the mass per unit volume of the medium. These two factors combine in the formula for sound speed: Sound Speed (v) = √(Bulk Modulus / Density) In short, the greater the bulk modulus and the lower the density, the faster sound can travel. Air vs...