• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.684-689
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• 2017

We examined the possibility of developing an early monitoring system using the shell valve movement activity of Pacific oyster (Crassostrea gigas) for early detection of low salinity water in coastal areas. At salinity levels of 30 psu and 20 psu, SVMs were detected $7.32{\pm}3.21times/hr$ and $7.11{\pm}3.90times/hr$, respectively, The patterns and times of SVMs were not significantly different between the two experiment phases. However, at 10 psu and 5 psu, shell valves were observed to be permanently closed in all experiments. Under combined condition (Group 1: temperature $15^{\circ}C$ ${\times}$ salinity 15 psu), SVMs were observed from 20 psu to 30 psu over a 2 - 3 hr period, and then remained closed. In Group 2 (temperature $30^{\circ}C$ ${\times}$ salinity 15 psu), SVMs were observed, which indicated that the physiological condition of the oysters reached a critical point. Thus, it may be possible to utilize SVMs as an early warning signal for low salinity water.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.4
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• pp.53-60
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• 2010

Biometrics are methods of recognizing a person based on the physiological or behavioral characteristics of his of her body. They are highly secure with little risk of loss or falsification by others. This paper has designed and implemented a security system of biometrics by precisely measuring heartbeat signals at two fingertips and using a photoplethysmogram, which is applicable to biometrics. A performance evaluation has led to the following result. The security system of biometrics for personal authentication which has been designed and implemented by this study has achieved a recognition rate of 90.5%. The security system of biometrics suggested here has merits of time saving and easy accessibility. The system is touch-based and collects the necessary biometrics information by simply touching the machine with fingers, so anyone can utilize the system without any difficulty.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.399-399
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• 2022

최근 국지성 호우 등 홍수방어 시설의 설계빈도를 초과하는 강우 발생으로 홍수피해가 증가하고 있다. 그 중 도시지역의 내수침수 피해는 전체 피해액의 50%를 넘는다. 그러나 우수관거의 노후화 및 통수능 부족으로 우수의 즉각적인 배출이 이루어지지 않아 침수피해가 증가하고 있다. 침수피해의 주요 원인 중 저지대 지역 및 우수관거의 통수능력 부족이 침수피해의 가장 큰 원인을 차지한다. 따라서 도심지의 경우 내수침수로 인한 피해가 증가하고 있는 점을 감안하면 배수관거와 연계한 저류시스템 구축으로 침수 빈발 지역의 치수 능력 향상을 통하여 경제적 피해를 저감시킬 수 있다. 저류시스템은 현장 노면수 저류를 위한 측구 저류조와 저류조 운영 시스템을 의미하며, 저류조 운영 시스템 모델에 대한 연구를 수행하였다. 측구 저류조 운영 시스템 구축을 위해서 현장 센싱(Sensing)데이터와 연계할 수 있는 정보체계 및 운영 시스템 모델이 필요하다. 이에 센서를 활용한 도심지 측구 저류조 운영 시스템 모델을 제시한다. 먼저 센서의 구성은 측구 저류조 내의 협소한 공간과 전원공급, 방진·방수 문제를 해결할 수 있도록 구성되어야 하며, 무전원 근거리 이동통신기술(RFID)을 적용하여 측구 저류조 운영 시스템 수집서버와 통신하여 센싱 데이터를 저장한다. 데이터는 근거리 RFID 리더기가 측구 저류조로부터 센싱 정보를 수신하여 통신모듈에 수신한 저류조 개폐도어 열림과 닫힘 시그널(signal), RFID의 고유 ID 등을 전달 받아 운영 시스템 내의 RFID 이력 DB(Database)에 기록한다. 기록된 정보는 각각 RFID 일련번호, 기록 시간, 동적센서 시그널 값 등이 저장되어 각각의 측구 저류조의 상태를 확인할 수 있어야 한다. 저류량 산정을 위해서 GIS기반의 하수도 시설물 속성 데이터를 포함하는 운영 시스템을 구성해야 한다. 운영 시스템은 수집된 센서정보를 시계열 단위로 분석하고 위치정보 기준으로 측구 저류조 내의 총 저류량 산출에 필요한 기초정보를 제공하며 결과를 표출한다. 따라서 하수도 시설물의 속성정보를 포함하여 측구 저류조 및 센서의 속성정보 정의가 필요하며, 공간정보 파일(Shape File)을 적용하여 GIS 운영 시스템을 구축하여야 한다. 운영 시스템은 저류조 만관상태와 총 저류량을 산출하여 침수위험 알림을 제공할 수 있으며, 예상 강우에 따른 도심지 피해를 역으로 예측하여 강우사상 빈도에 따른 측구 저류조 체적을 결정할 수 있다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.5
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• pp.256-264
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• 2023

Smart farm technology using IoT is one of the technologies that can increase productivity and improve the quality of agricultural products in agriculture, which is facing difficulties due to the decline in rural population, lack of rural manpower due to aging, and increase in diseases and pests due to climate change. . Smart farms using existing IoT simply monitor farms, implement smart plant growers, and have automatic greenhouse opening and closing systems. This paper implements a smart farm system based on MQTT, an industry standard protocol for the Internet of Things, and Node-RED, a representative development middleware for the Internet of Things. First, data is extracted from Arduino sensors, and data is collected and transmitted from IoT devices using the MQTT protocol. Then, Node-RED is used to process MQTT messages and store the sensing data in real time in MongoDB, a representative NoSQL, to store the data. Through this smart farm system, farm managers can use a computer or mobile phone to check sensing information on the smart farm in real time, anytime, anywhere, without restrictions on time and space.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.66-72
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• 2009

The detection methods are required to monitor and diagnose the abnormality on the insulation condition inside a gas-insulated switchgear (GIS). Due to a good sensitivity to the products decomposed by partial discharges (PDs) in $SF_6$ gas, the development of a SWNT gas sensor is actively in progress. However, a few numerical studies on the diffusion mechanism of the $SF_6$ decomposition products by PD have been reported. In this study, we modeled $SF_6$ decomposition process in a chamber by calculating temperature, pressure and concentration of the decomposition products by using a commercial CFD program in conjunction with experimental data. It was assumed that the mass production rate and the generation temperature of the decomposition products were $5.04{\times}10^{-10}$ [g/s] and over 773 K respectively. To calculate the concentration equation, the Schmidt number was specified to get the diffusion coefficient functioned by viscosity and density of $SF_6$ gas instead rather than setting it directly. The results showed that the drive potential is governed mainly by the gradient of the decomposition concentration. A lower concentration of the decomposition products was observed as the sensors were placed more away from the discharge region. Also, the concentration increased by increasing the discharge time. By installing multiple sensors the location of PD is expected to be identified by monitoring the response time of the sensors, and the information should be very useful for the diagnosis and maintenance of GIS.

• Journal of the Korean GEO-environmental Society
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• v.11 no.9
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• pp.55-60
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• 2010

This study are carried out to an lab model tests to develop a construction method that solidifies high-water content cohesive soil by using filter type drain and vacuum pressure, and that stabilizes the ground by accelerating horizontal drain at incline or in tunnel. The calibration chamber was designed within length of 1.5m and height of 50cm, and a drainage hole for preconsolidation, a switchgear and a piezometer were installed at the bottom part of the chamber. Also, a settlement gage was installed at the top part so that it can measure the settlement by time. The calibration ground basis was made in a form of thin layer from kaolinite and bentonite in 9:1 ratio stirred at 130% water content condition. A filter type drain was installed at chamber center and a vacuum pressure of 0.8MPa was applied through a hose linked to the cap at the top part, then, the settlement was measured in every 1 hour interval. After experiment, the moisture contents were measured by position, then, verified the increase of solidity of the ground through a triaxial compression test on undisturbed profile. After 11 days from the effective date, it was observed that the settlement decreased by maximum 35mm and the water content ratio was reduced by 38% at most while the solidity of the ground increased by 5~8 times greater than before preconsolidation.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.221-229
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• 2013

In this paper, the image formation by the motion compensation technique for Synthetic Aperture Radar system(SAR) were realized through the computer simulation. The motion compensation technique performed image data with the range compression, the compensation procedure, the azimuth compensation and the noise elimination procedure. The range compression procedure transform the SAR raw data into the frequency domain and correlate with the range reference function and then inversely transform into the time domain. The compensation procedure contain the aircraft fluctuations compensation and the radar image degrading effect elimination procedure which was caused by image formation algorithm itself. The aircraft fluctuations compensation procedure perform the first stage which correct the phase angle and the second stage which calculate the Doppler frequency and determine the coordinate of the received signal. The radar image degrading effect elimination procedure also perform range migration compensation and the image defocussing effect compensation. The azimuth compression procedure transform the compensation data to the frequency domain and correlate with the azimuth reference function. The azimuth correlated data are inversely transformed to the time domain which is called SAR image data. When the above procedure were completed, the image data contains the received signals mixed with noise. The threshold technique was applied to elimination the noise from the mixed image data.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.131-131
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• 2009

최근 환경규제가 강화되면서 친환경적인 전력생산 요구 등의 외부환경 변화에 따른 우리나라의 전력구조가 기존의 중압 집중형 발전을 탈피한 분산전원 발전에 대한 관심이 증대되고 있는 실정이다. 특히, 분산전원으로서의 전력생산은 공급의 안전성, 경쟁력 및 에너지의 지속성 등이 요구되어지는데, 재생에너지가 가지고 있는 에너지 지속성의 한계 및 설치의 제약성을 탈피할 수 있는 시스템으로 현재 연료전지시스템이 가장 근접해 있는 실정이다. 즉, 도시가스 인프라가 우수하고 인구조밀 지역이 많은 우리나라의 특성상 각 가정 및 건물에 쉽게 설치하고 공급의 안전성을 갖는 건물용 연료전지는 최근 가장 각광받고 있는 분산전원 시스템 중의 하나이다. 올해부터 모니터링사업의 일환으로 수용가에 설치 될 연료전지 시스템이 얼마나 안정적으로 전기와 열을 각 가정에 공급하고 시스템의 안전성을 확보하는 가는 건물용 연료전지의 분산전원으로서의 가능성 및 국민의 수용성을 증대시키는 중요한 역할을 할 것이다. 연료전지시스템은 상용전력과 연계되어 있기 때문에 시스템의 안정성 뿐만 아니라 상용전력의 변화에 대응하여 안정적인 운전을 하는지에 대한 평가가 필수적이다. 이에 따라 본 연구에서는 가정용 연료전지시스템의 성능 및 안전성평가의 일환으로 계통연계형 전력변환장치의 성능 및 안전성을 평가 하고자 한다. 연료전지 검사를 위한 계통연계형 전력변환장치의 시험평가 항목으로는 크게 정상특성성능시험, 보호기능성능시험, 과도응답특성성능시험 및 외부사고성능시험 등으로 나뉘어진다. 본 연구에서는 외부사고 성능시험 항목들인 출력측 단락시험, 계통전압 순간정전?순간강하시험 및 부하차단 시험 등을 통하여 외부사고에 대한 성능 및 안전성을 평가하였다. 외부사고 성능시험의 주 목적은 시스템의 이상 운전이 아니라 외부의 영향에 따른 시스템의 안전성 및 전력품질을 평가한다. 출력측 단락시험을 수행하기 위해서 전력변환장치를 정격 출력 전압, 정격 출력 주파수 및 정격 출력에서 운전한 후, 교류 전원장치는 단락 전류를 검출하여, 사고 발생 후 0.3초 이내에 개방하도록 설정하였다. 여기서, 단락 저항 Rsc를 정격 전류의 10배 이상에 해당하는 부하와 같은 값으로 설정하였다. 스위치 SWSC를 폐로하여 단락 상태를 만들며, 이 때 전력변환장치의 출력전류와 차단 또는 정지 시간을 측정하였다. 실험 결과에 대한 판정기준은 단락전류를 검출하여 0.5초 이내에 개폐기 개방 또는 게이트 블록 기능이 동작하여 시스템을 안정하게 정지시키고 시스템 어떤 부위에도 손상이 없어야 한다. 실험 결과 파워컨디셔너의 출력전류 및 차단 또는 정지된시간이 40ms로 나타났고, 출력전류의 파형도 매우 안정함을 볼 수 있었다. 이와 같이 모든 실험을 수행한 결과 외부사고에 대하여 시스템이 안전하게 정지하는 등 연료전지 시스템의 안전성을 확인하였다.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.287-294
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• 2003

There are a lot of curved subway stations in Seoul metropolitan area. These must be straightly constructed as many as possible. But some of stations are roundly designed and built in order to avoid pre-existed underground obstacle such as basement of high rise building, underground gas or water pipe line and subway stations from another line. As shown fig 1, one of the biggest problem occurring curved subway station is considered large gap between platform and vehicle when vehicle completely stop at the station. The gap potentially is in existence to subway passenger as very dangerous factors in rush hours. If passenger accidentally drop their food or leg between this gap when they get on the train and train leaves station, the passenger will be seriously injured by vehicle. In this paper, various design and instruments are introduced and best solution for this matter will be presented. In order to eliminate any possibility of accident happened gap between platform and vehicle, KRRI(Korea Railroad Research Institute) have been developed new safety instrument. These technologies were applied for patent by KRRI. These mechanisms will provide confidence as well as safety to Korean subway passenger

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.315-322
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• 2021

This study analyzes the Required Safe Egress Time (RSET), in the event of a fire at a welfare center for the disabled, using the emergency passage according to the floor arrangement of users to evaluate the safety and the difference in RSET for each emergency passage using the Pathfinder simulation program to suggest an efficient evacuation method. As a result of RSET, it was found that there is no problem in evacuation safety for the current state of the facility's personnel allocation by satisfying the standard RSET in case of fire, and evacuation can be completed safely by evacuating through stairs rather than using elevators if possible. It is necessary for employees to be provided sufficient education and training in advance so that they can evacuate effectively with the disabled in case of fire. This study gives significance in saving many precious lives and safely evacuate in case of fire as evacuation routes were secured through the design, construction and operation of facilities for the disabled and the RSET was shortened through regular evacuation practices. It is necessary to discuss the further RSET studies based on the automatic fire shutters open or not when a fire occurs at a specific location following the installation of automatic fire shutter at the entrance of each floor of the facilities.