• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.525-531
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• 2015

In this paper, a novel impact sensing device for an ESAF(Electronic Safe and Arming Fuze) is presented. An impact sensing device is mounted in front of a weapon, and it detects an impact when it crashes against a target. There are two main design requirements to enhance the firing functional reliability of the ESAF; an operational reliability and a reduced latency, which is a delay time needed for sensing the impact. The design method of the contact-type impact sensing device, which employs an FPCB(Flexible Printed Circuit Board) so it can be used other weapons, is proposed. The tests demonstrated that the design described in this work show a reduced delay time with ensuring the operational reliability.

• Journal of Biosystems Engineering
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• v.22 no.1
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• pp.49-58
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• 1997

Finding of internal quality is crucial for getting under control quality of watermelon after harvest. A maturity sensing device of watermelon using repulsion characteristics was developed and evaluated. In this study, five different sensing probes were used to detect the physical changes after impact on watermelons. Total 15 watermelons were tested and evaluated into two classes: ripe and unripe. It was difficult to detect the overripe watermelons using the proposed sensor. Therefore, the results showed that the developed sensor could be used to separate unripe watermelons after harvest. The results from this study are summarized as follows. 1. It was successful to distinguish between the ripe and unripe watermelon by sensing the elastic characteristics on impact. 2. The hemisphere was best for the shape of sensing part because the hemisphere concentrate stress in impact part. 3. Among the five type developed sensor, the 1, 2, 3. 5-type sensor showed good character in distinguishing between ripe and unripe watermelon.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.763-764
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• 2013

A three-dimensional image capturing device and its signal processing algorithm and apparatus are presented. Three dimensional information is one of emerging differentiators that provides consumers with more realistic and immersive experiences in user interface, game, 3D-virtual reality, and 3D display. It has the depth information of a scene together with conventional color image so that full-information of real life that human eyes experience can be captured, recorded and reproduced. 20 Mega-Hertz-switching high speed image shutter device for 3D image capturing and its application to system prototype are presented[1,2]. For 3D image capturing, the system utilizes Time-of-Flight (TOF) principle by means of 20MHz high-speed micro-optical image modulator, so called 'optical resonator'. The high speed image modulation is obtained using the electro-optic operation of the multi-layer stacked structure having diffractive mirrors and optical resonance cavity which maximizes the magnitude of optical modulation[3,4]. The optical resonator is specially designed and fabricated realizing low resistance-capacitance cell structures having small RC-time constant. The optical shutter is positioned in front of a standard high resolution CMOS image sensor and modulates the IR image reflected from the object to capture a depth image (Figure 1). Suggested novel optical resonator enables capturing of a full HD depth image with depth accuracy of mm-scale, which is the largest depth image resolution among the-state-of-the-arts, which have been limited up to VGA. The 3D camera prototype realizes color/depth concurrent sensing optical architecture to capture 14Mp color and full HD depth images, simultaneously (Figure 2,3). The resulting high definition color/depth image and its capturing device have crucial impact on 3D business eco-system in IT industry especially as 3D image sensing means in the fields of 3D camera, gesture recognition, user interface, and 3D display. This paper presents MEMS-based optical resonator design, fabrication, 3D camera system prototype and signal processing algorithms.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.832-837
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• 1991

After many years of proliferation, the nuclear industry is indebted for a formidable consequence, the safe management of spent fuel. Naturally, the high radioactivity involved with such process motivates the development of effective telerobotic systems. Nevertheless, the existing master-slave type of tele manipulators are limited in effectiveness by the human operator's limited sensory and manipulation capabilities. This paper presents the result of a research effort to resolve such problems by assigning the slave manipulator a certain degree of intelligence; sensing and actuation. In the presented system, a perception-action loop is achieved using ultrasonic range sensor and laser distance sensor interfaced with the PUMA 760 industrial robot system, and applied to automating impact wrenching task for unbolting the lid of nuclear spent fuel cask. The perception-action loop performs determination of the cask location, collision avoidance and centering of the impact wrench onto the bolt head. To aid the insertion task and to provide versatility a mounting module consisting of an RCC device and an automatic tool changer is designed and implemented. The performance of the developed system is tested on the model cask and the result is given.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1657-1662
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• 2014

In this paper, the impact of substrate bias($V_{BS}$) on the zero capacitor RAM(Z-RAM) in n-channel junctionless multiple gate MOSFET(MuGFET) has been analyzed experimentally. Junctionless transistors with fin width of 50nm and 1 fin exhibits a memory window of 0.34V and a sensing margin of $1.8{\times}10^4$ at $V_{DS}=3.5V$ and $V_{BS}=0V$. As the positive $V_{BS}$ is applied, the memory window and sensing margin were improved due to an increase of impact ionization. When $V_{BS}$ is increased from 0V to 10V, not only the memory window is increased from 0.34V to 0.96V but also sensing margin is increased slightly. The sensitivity of memory window with different $V_{BS}$ in junctionless transistor was larger than that of inversion-mode transistor. A retention time of junctionless transistor is better than that of inversion-mode transistor due to low Gate Induced Drain Leakage(GIDL) current. To evaluate the device reliability of Z-RAM, the shifts in the Set/Reset voltages and current were measured.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.2
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• pp.115-122
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• 2007

The MPC(Moisture Protected Computer) system is completely unique. It was recently invented in Korea and it is a technological break-through in the field of computer systems. It will be instrumental in the development of a complete moisture air-tight capability and will work well in field environments. The MPC includes the following: 1) An enclosed design. 2) Moisture proof computer enclosure joints. 3) System dust protection & an impact buffing system. 4) A normal temperature maintenance system when the temperature inside the computer is low. 5) The ability to generate heat and a radiate system inside the computer 6) An automatic power input sensing controller device. 7) A safety device in case of mis-operation. 8) A proper admission procedure for various tests. Because of the above, and as a result of temperature property experiments, there aren't any operational problems. The result of this treatise could provide very important data for verification of cases involving: using strong materials to protect against explosions, searching for ways to make the size and weight small, and for making repairs easier. As a result, it could achieve price and function competitiveness in advanced countries such as the USA and in Europe.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.1
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• pp.132-138
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• 2011

A micromachined silicon accelerometer capable of surviving and detecting very high accelerations(up to 200,000 times the gravitational acceleration) is necessary for a high impact accelerometer for earth-penetration weapons applications. We adopted as a reference model a piezoresistive type silicon micromachined high-shock accelerometer with a bonded hinge structure and performed structural analyses such as stress, modal, and transient dynamic responses and sensor sensitivity simulation for the selected device using piezoresistive-structural coupled-field analysis. In addition, structural optimization was introduced to improve the performances of the accelerometer against the initial design of the reference model. The design objective here was to maximize the sensor sensitivity subject to a set of design constraints on the impact endurance of the structure, dynamic characteristics, the fundamental frequency and the transverse sensitivities by changing the dimensions of the width, sensing beams, and hinges which have significant effects on the performances. Through the optimization, we could increase the sensor sensitivity by more than 70% from the initial value of $0.267{\mu}V/G$ satisfying all the imposed design constraints. The suggested simulation and optimization have been proved very successful to design high impact microaccelerometers and therefore can be easily applied to develop and improve other piezoresistive type sensors and actuators.

• Advances in nano research
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• v.15 no.2
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• pp.155-163
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• 2023

Exercise is beneficial to the body in some ways. It is vital for people who have heart problems to perform exercise according to their condition. This paper describes how an Android platform can provide early warnings of fatigue during wushu exercise using Photoplethysmography (PPG) signals. Using the data from a micro-electro-mechanical system (MEMS) gyroscope to detect heart rate, this study contributes an algorithm to determine a user's fatigue during wushu exercise. It sends vibration messages to the user's smartphone device when the heart rate exceeds the limit or is too fast during exercise. The heart rate monitoring system in the app records heart rate data in real-time while exercising. A simple pulse sensor and Android app can be used to monitor heart rate. This plug-in sensor measures heart rate based on photoplethysmography (PPG) signals during exercise. Pulse sensors can be easily inserted into the fingertip of the user. An embedded microcontroller detects the heart rate by connecting a pulse sensor transmitted via Bluetooth to the smartphone. In order to measure the impact of physical activity on heart rate, Wushu System tests are conducted using various factors, such as age, exercise speed, and duration. During testing, the Android app was found to detect heart rate with an accuracy of 95.3% and to warn the user when their heart rate rises to an abnormal level.

• Korean Journal of Remote Sensing
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• v.33 no.6_2
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• pp.1139-1149
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• 2017

Measuring tree's volume is very important input data of various environmental analysis modeling However, It's difficult to use economical and equipment to measure a fragmented small green space in the city. In addition, Trees are sensitive to seasons, so we need new and easier equipment and quantification methods for measuring trees than lidar for high frequency monitoring. In particular, the tree's size in a city affect management costs, ecosystem services, safety, and so need to be managed and informed on the individual tree-based. In this study, we aim to acquire image data with UAV(Unmanned Aerial Vehicle), which can be operated at low cost and frequently, and quickly and easily quantify a single tree using SfM-MVS(Structure from Motion-Multi View Stereo), and we evaluate the impact of reducing number of images on the point density of point clouds generated from SfM-MVS and the quantification of single trees. Also, We used the Watertight model to estimate the volume of a single tree and to shape it into a 3D structure and compare it with the quantification results of 3 different type of 3D models. The results of the analysis show that UAV, SfM-MVS and solid model can quantify and shape a single tree with low cost and high time resolution easily. This study is only for a single tree, Therefore, in order to apply it to a larger scale, it is necessary to follow up research to develop it, such as convergence with various spatial information data, improvement of quantification technique and flight plan for enlarging green space.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.156-157
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• 2012

단일 셀에서 비휘발성 및 고속의 휘발성 메모리를 모두 구동할 수 있는 다기능 메모리는 모바일 기기 및 embedded 장치의 폭발적인 성장에 있어 그 중요성이 커지고 있다. 따라서 최근 이러한 fusion기술을 응용한 unified RAM (URAM)과 같은 다기능 메모리의 연구가 주목 받고 있다. 이러한 다목적 메모리는 주로 silicon on insulator (SOI)기반의 1T-DRAM과 SONOS기술 기반의 비휘발성 메모리의 조합으로 이루어진다. 하지만 이런 다기능 메모리는 주로 단결정기반의 SOI wafer 위에서 구현되기 때문에 값이 비싸고 사용범위도 제한되어 있다. 따라서 이러한 다기능메모리를 다결정 실리콘을 이용하여 제작한다면 기판에 자유롭게 메모리 적용이 가능하고 추후 3차원 적층형 소자의 구현도 가능하기 때문에 다결정실리콘 기반의 메모리 구현은 필수적이라고 할 수 있겠다. 본 연구에서는 다결정실리콘을 이용한 channel recessed구조의 다기능메모리를 제작하였으며 각 1T-DRAM 및 NVM동작에 따른 memory 특성을 살펴보았다. 실험에 사용된 기판은 상부 비정질실리콘 100 nm, 매몰산화층 200 nm의 SOI구조의 기판을 이용하였으며 고상결정화 방법을 이용하여 $600^{\circ}C$ 24시간 열처리를 통해 결정화 시켰다. N+ poly Si을 이용하여 source/drain을 제작하였으며 RIE시스템을 이용하여 recessed channel을 형성하였다. 상부 ONO게이트 절연막은 rf sputter를 이용하여 각각 5/10/5 nm 증착하였다. $950^{\circ}C$ N2/O2 분위기에서 30초간 급속열처리를 진행하여 source/drain을 활성화 하였다. 계면상태 개선을 위해 $450^{\circ}C$ 2% H2/N2 분위기에서 30분간 열처리를 진행하였다. 제작된 Poly Si MFM에서 2.3V, 350mV/dec의 문턱전압과 subthreshold swing을 확인할 수 있었다. Nonvolatile memory mode는 FN tunneling, high-speed 1T-DRAM mode에서는 impact ionization을 이용하여 쓰기/소거 작업을 실시하였다. NVM 모드의 경우 약 2V의 memory window를 확보할 수 있었으며 $85^{\circ}C$에서의 retention 측정시에도 10년 후 약 0.9V의 memory window를 확보할 수 있었다. 1T-DRAM 모드의 경우에는 약 $30{\mu}s$의 retention과 $5{\mu}A$의 sensing margin을 확보할 수 있었다. 차후 engineered tunnel barrier기술이나 엑시머레이저를 이용한 결정화 방법을 적용한다면 device의 특성향상을 기대할 수 있을 것이다. 본 논문에서는 다결정실리콘을 이용한 다기능메모리를 제작 및 메모리 특성을 평가하였다. 제작된 소자의 단일 셀 내에서 NVM동작과 1T-DRAM동작이 모두 가능한 것을 확인할 수 있었다. 다결정실리콘의 특성상 단결정 SOI기반의 다기능 메모리에 비해 낮은 특성을 보여주었으나 이는 결정화방법, high-k절연막 적용 및 engineered tunnel barrier를 적용함으로써 해결 가능하다고 생각된다. 또한 sputter를 이용하여 저온증착된 O/N/O layer에서의 P/E특성을 확인함으로써 glass위에서의 MFM구현의 가능성도 확인할 수 있었으며, 차후 system on panel (SOP)적용도 가능할 것이라고 생각된다.