• Korean Journal of Optics and Photonics
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• v.29 no.2
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• pp.77-84
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• 2018

We analyze the link availability of terrestrial free-space optical (FSO) communication systems in Korea. For this purpose, we utilize several theoretical models to calculate the power losses induced by absorption and scattering in the atmospheric channel, using five-year meteorological data for three major cities in Korea (Seoul, Busan, and Daejeon). Also, we estimate the power variations at the receiver caused by scintillation in the data. Those power losses and variations are used to estimate the availability of FSO links in the three cities. The results show that link availability is estimated to be over 95% in Daejeon for a 3.5-km FSO link, when the transmitter power and receiver diameter are greater than 10 dBm and 7 cm respectively. Slightly worse link availabilities are obtained for Busan and Seoul.

• Journal of the KSME
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• v.44 no.1
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• pp.27-27
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• 2004

미국 국방부 소속 육군차량사업부(National A Automotive Center)는 대체에너지를 이용한 군용 차량 개발을 위해 Michigan 주 Rochester Hills에 위치한 E Energy Conversion Devices(ECD) 사와 일부 기술 개발 에 대한 기술 제휴를 한다고 발표했다. 국방부는 태양전 지와 수소를 연료로 사용하는 대체에너지 차량을 개발하 기 위해 ECD에 1단계 연구에 필요한 연구비를 지원했다. 이번 연구에는 연료전지를사용한차량개발을위해 5 500,$\omega$0달러가 투자되는데, Texaco Ovollic Hydrogen S Systems(TOHC)의 고체 휴대용 수소 연료와 채충천 (refueling) 시스탬이 주요 개발 목표로 설정됐다. ECD의 역할은 최근 개발된 Toyota Prius에 시범 적으로 장착된 저압 고체형 수소 저장 시스템의 기술을 군용 차량에 알맞게 전환시키는 것이다. TOHC와 ECD가 개발한 고체형 수소 보관 시스댐은 고압을 요구하는 연료전지 차량의 수소 저 장 시스템이 갖고 있는 많은 문제점들을 해결할 수 있을 것으로 기대되는 연료전지를 이용한 엔진 개발 중 최신 기술이다. 특히 전투 상황에서 차량이 폭발하기 쉬운 수소 저장 탱크를 장착한 채 전 장으로간다는 것은적에게 노출 될 경우자살과마찬가지인 치명적인 피해를 입을수 있다. 이 프로젝트의 개요를 살펴보면, 수소 저장 시스템은 적어도 약 lOkg의 수소를 적은 용적 내에 낮은 압력에서 안전하게 고체 상태로 저장할 수 있다. 이 고체 저장 용기는 하루에 두 번 1.7kg의 수소를 10분 이내에 재급유할 수 있다. 수소는대부분고압가스형태나저온액체 형태로보관된다. 기체나액체 형태의 수소는 연료전 지에 사용되기에는 적합하지 않은 점이 많다. Ovonie 수소 저장 방법은 수소를 저압 고체 형태 ( (metal hydride)로 보관하는 방법으로, 고압 기체나 저온 액체가 갖고 있는 많은 문제점들을 해결 할수있다. 그림을 참조하면 고체 형태의 수소 보관 방법이 다른 보관 방법에 비교해 단위 체적당 최고 6배 많은수소질량을보관할수 있다. 이 고체 형태의 보관방법은수소가적절한합금과평형 압력 이 상의 환경에 놓일 경우 합금에 홉착되는 현상을 이용하고 있다. 수소를 흡수한 합금은 새로운 특성 을 가진 metal hydride로 변하게 된다. 이 과정 에서 열이 부산물로 발생한다. 반대로 수소를 metal hydride로부터 분리시키기 위해서는 합금을 가열해야 한다.

• The Transactions of the Korea Information Processing Society
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• v.6 no.8
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• pp.2031-2041
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• 1999

In this paper, we present the HVIS (Hybrid Video Information System) which bolsters up meaning retrieval of all the various users by integrating feature-based retrieval and annotation-based retrieval of unformatted formed and massive video data. HVIS divides a set of video into video document, sequence, scene and object to model the metadata and suggests the Two layered Hybrid Object-oriented Metadata Model(THOMM) which is composed of raw-data layer for physical video stream, metadata layer to support annotation-based retrieval, content-based retrieval, and similarity retrieval. Grounded on this model, we presents the video query language which make the annotation-based query, content-based query and similar query possible and Video Query Processor to process the query and query processing algorithm. Specially, We present the similarity expression to appear degree of similarity which considers interesting of user. The proposed system is implemented with Visual C++, ActiveX and ORACLE.

• The Journal of the Korea Contents Association
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• v.8 no.5
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• pp.104-112
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• 2008

RFID/USN is considered important basic infra of ubiquitous community and tried practical adaption through various research. Specially, there is during researcher progresses for stock and state management of logistics to let you get at u-mart systems. It discern thing from warehouse to deliver as adhere RFID tag of palette in keeping unit of article and construct form of thing to analyze information of environment status using sence module based on function of wireless communication. in the paper, propose composition of customer satisfaction system using RFID chip in u-Mart status management system based on RFID/USN and according to analysis specific information of commodity, propose movement reader device to offer real-time information from customer. And it presents the improvement program for the provision of product information which is appropriate uses the RFID chip and the provision of control information in the customer who is a core of consuming.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.827-830
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• 2013

Due to strong wind of smartphone, change in human life is facing 21 Century's new revolution. The end of 2012, The record rate of supply of smartphone is up to 58.8 percent. So the reputation of IT power are continuing. Korea is boasting IT infrastructure, and the reputation of IT power with rapidly evolving. But Korea is one of OECD country with the longest working hours and in labor productivity, yet is located in the lower rank. Now, common social issues such as low-carbon, green growth, low birthrate, graying, labor productivity growth, the reduce greenhouse gas is constantly increasing in worldwide. So Smart Work is getting attention as a way to resolve this. In this paper, we study the impact of small business on local economy and the status information of small business on statistical point of view. And we offer the smart work countermeasures of small business through detailed action elements and the model proposed fot driving factor for the promotion of smart work. Through this, we propose the IT system model for The SMEs-type smart work system.

• Korean Journal of Optics and Photonics
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• v.27 no.3
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• pp.95-100
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• 2016

High-power quasi-continuous-wave (qcw) operation in Yb-doped double-clad fiber lasers with near-diffraction-limited quality of the output beam is reported. Based on numerical simulation, we built a simple, all-fiberized Yb fiber laser, and a fiber-based master-oscillator power amplifier (MOPA). Both laser systems have successfully produced qcw output with average power greater than 150 W at 1080 nm and 10 ms pulse duration at 10 Hz repetition rate, corresponding to a peak power greater than 1.5 kW for 205 W of pump power at 976 nm. Laser performance, including beam quality and slope efficiency, was characterized in both configurations. Prospects for power scaling and applications are discussed.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.361-365
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• 2005

An absolute interferometer system with multiple point-sources is devised for tile 3-D measurement of rough surface profiles. The positions of the point sources are determined to be the system parameters that influence the measurement accuracy, so they are calibrated precisely prior to performing actual measurements. For the calibration, a CCD camera composed of a two-dimensional array of photo-detectors was used. Performing optimization of the cost function constructed with phase values measured at each pixel on the CCD camera, the position coordinates of each point source is precisely determined. Measurement results after calibration performed for the warpage inspection of chip scale packages (CSPs) demonstrate that the maximum discrepancy is 9.8 mm with a standard deviation o( 1.5 mm in comparison with the test results obtained by using a Form Taly Surf instrument.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.311-317
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• 2010

In the paper, we propose an improved mobility method of modular robots by physical docking in the uneven environments. The modular robot system consists of autonomous docking device, 3 DOF robotic arm, motion controller, and main controller. Real-time location and direction of the robot are estimated using inner GPS and they are used to control direction and path of each robot for physical docking between modular robots. We design a navigation algorithm of modular robot using physical docking and cooperative navigation in the environment with broken road and low stair. The proposed method is verified by navigation experiments of three developed modular robots in the uneven environments.

• Korean Journal of Remote Sensing
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• v.37 no.6_2
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• pp.1891-1900
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• 2021

Fine particulate matter (FPM; diameter ≤ 2.5 ㎛) is frequently found in metropolitan areas due to activities associated with rapid urbanization and population growth. Many adolescents spend a substantial amount of time at school where, for various reasons, FPM generated outdoors may flow into indoor areas. The aims of this study were to estimate FPM concentrations and categorize types of FPM in schools. Meteorological and chemical variables as well as satellite-based aerosol optical depth were analyzed as input data in a random forest model, which applied 10-fold cross validation and a grid-search method, to estimate school FPM concentrations, with four statistical indicators used to evaluate accuracy. Loose and strict standards were established to categorize types of FPM in schools. Under the former classification scheme, FPM in most schools was classified as type 2 or 3, whereas under strict standards, school FPM was mostly classified as type 3 or 4.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.2
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• pp.74-82
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• 2015

In this study, a BMW plant process control system model which produces BMW is suggested and the BMW plant process controller with the following functions is developed. The first function is to operate the electronic overload relays to stop the blower for a certain period of time and to re-operate it again when the blower is overloaded. The second function is to close the motor operated valve automatically in case of power failure to prevent the circulation from the guided tank to the compost throwing tank and to block leak from the compost throwing tank due to the failure of ball valve. The third function is to transfer produced BMW from the concentration tank to 4 storage tanks for automatic managing of the BMW output. A device to measure the signal of the BMW plant process controller and a test equipment are developed. The designed BMW plant process controller is checked to see if it operates correctly according to the design specifications. The sequence control method based on BMW plant process controller is developed at a low cost in this study, so it is expected to bring improvements in the stability and the efficiency of system and to cause reductions in the operation and the management costs in the future.