• Journal of IKEEE
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• v.23 no.4
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• pp.1448-1456
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• 2019

In this study, when applying LED light sources within a single-span glass greenhouse for growing crops, the illumination simulation was performed on the ceiling and side of the glass greenhouse to determine the selective placement and effective light transmission of Si series solar cells and dye-sensitive solar cells (DSSC) for supplying LED power source. In addition, energy saving effects of glass greenhouses were analyzed for optimum lighting control when both daylight and LED light sources are considered in glass greenhouses.

• Korean Journal of Food Science and Technology
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• v.24 no.6
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• pp.524-527
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• 1992

To measure of important variables such as temperature, weight, and relative humidity in food processing process, computer-aided data acquisition system was composed of 16 bit microcomputer and PCL-711S interface board. Process variables in dehydration and storage of food were measured through sensors, converters, and computer system which were operated by the PC-LabDAS software for data acquisition, process control, and data analysis. The relationship between measured values of process variables and the output voltages of ADC showed more than 0.99 in $r^2$ value. Response time of sensors was enough fast to measure minute values changed in a moment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.240-243
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• 2001

As electronic industry and radio communication technologies progress, mankind enjoys its abundant life. On the other hand, it becomes possible that the electrical and electronic equipments are on light weight, small size, high speed, broad bandwidth, and operation by small energy. At the same time, many social problems like EMI/EMS by electromagnetic waves occur. Therefore, tile organizations such as CISPR, FCC, ANCI, etc., have provided the standards of electromagnetic wave environments for the countermeasure of the EMC. In this paper, we designed and studied a new EMI filter for multi-tap in the frequency band from 150 kHz to 30 MHz.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1719-1721
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• 2005

현재 지구 환경 오염에 관한 관심이 증가하면서, 공해가 없는 자연 에너지원에 대한 연구가 많이 진행되고 있다. 그 중에서도 태양전지 분야중 염료감응형 태양전지(DSC)는 Si계 태양전지와 비교하여 낮은 제조비용등 여러 가지 이유로 최근 많은 연구가 진행되고 있다. 따라서 DSC 발전 시스템의 효율 향상이 요구된다. 본 연구에서는 태양전지 분야 중에서 독립적인 발전설비가 필요한 도서 및 산간 지역에 전력을 안정적으로 공급할 수 있는 소형발전용의 설비로 "전압 및 전류의 피드백을 통한 DSC Cell의 독립전원의 안정화"에 관해 연구하였다. DSC Cell측의 DC입력을 받아 Boost Converter로 승압 후 Full Bridge 인버터를 사용하여 단상 220V 60Hz의 상용전원으로 변환하였다. 여기서는 32Bit 마이크로프로세서인 DSP TMS320F2812의 A/D변환기능을 이용하여 Boost Converter의 스위칭과 Full Bridge 인버터의 스위칭을 제어하였다. 특히 TMS320F2812의 RTC(Real Time Clock)를 이용하여 출력전압의 안정성 향상에 주목적을 두었다. 실험결과 출력단에서는 220V 변동범위 0.2% 주파수 60Hz의 상용전원을 얻었으며, 프로그램의 개선을 통하여 출력전압의 변동범위를 감소시켜야 될 것이다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.1 no.1
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• pp.70-78
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• 2002

Advanced safety vehicle (ASV) equipped with intelligent drivers advisory functions for controlling vehicle to follow the lead vehicle and/or warning drivers on forward traffic impediments according to the roadway and traffic circumstances has been recently developed and on the market internationally. Standardization processes for ASV system functions have been issued in IS0/TC204 Working Group 14 (Vehicle/Roadway Warning and Control System) since 1995. Research projects developing test and evaluation technologies for ASV in establishing safety standards and/or conformity related to the national roadway and traffic circumstances are under study internationally. In Korea, an integrated test and evaluation Program was developed for the assessment of adaptive cruise control (ACC) system under the ITS research and development projects funded by the Ministry of Construction and Transportation (MOCT). This paper demonstrates the integrated test and evaluation Programs for ACC system based on the draft international standard with related to the domestic roadway and traffic conditions. Field tests fulfilled under the scenarios based on the integrated test & evaluation programs for ACC system are discussed along with a review of earlier research work regarding international standards and the safety regulations.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.6
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• pp.90-101
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• 2016

This study was initiated to develop an algorithm for traffic condition adaptive optimal traffic signal control for isolated intersections based on the vehicle trajectory data. The algorithm determines the optimal cycle length, phase lengths, phase sequences using the data collected under V2X communication environment every second. In addition, the algorithm utilizes a traditional feature of the actuated signal control, gap-out, using traditional detector systems to consider the mixture of normal vehicles and vehicles equipped with the V2X communication function. The performance of the algorithm was compared with that of the fixed signal timing plan which was optimized with Synchro under a microscopic traffic simulation-based test bed. As a result, the overall performance, including average delay, average stop delay, the number of stops, and average speed, are improved apparently. In addition, the amount of improvement get bigger as the traffic volume in the intersection as well as the number of vehicles equipped with the V2X communication function increase.

• Journal of Practical Agriculture & Fisheries Research
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• v.23 no.1
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• pp.59-66
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• 2021

This study aimed to a basic research for the development of dye-sensitized solar cells that the wavelength band required for crop growth is passed, and the wavelength band that is not necessary for crop growth can be used for the generation of electricity. The transmissivity according to the illuminance was about 10% higher in the Blue filter and the Green filter than in the Red filter, but the transmissivity according to the PPFD was about 10% higher in the Red filter and the Blue filter than in the Green filter. In addition, the greenhouse attached with 30% infrared blocking filter was predicted to have a lower air temperature than other greenhouses, but it was investigated that there was no significant difference. Therefore, it was investigated that the application of the infrared cut filter would not be appropriate in a greenhouse that controls the temperature by opening a window. As a result of investigating, it was found that the Green and Blue filter greenhouses had the severe overgrowth and the stems grew weaker. The fresh weight of paprika in the infrared blocking filter greenhouse was the highest at 678.9g, and the growth of Red filter and the control greenhouses was relatively poor. Photosynthetic rate, amount of transpiration, and stomatal conductivity were the infrared blocking filter and control greenhouse higher than others. On the other hand, the water use efficiency did not show a big difference.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.397-402
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• 2016

To produce adequate electricity in nuclear and thermal power plants, an optimal amount of steam should be supplied to a generator connected to high- and low-pressure steam turbines. A turbine output control device, which is a special steam valve employed to supply or interrupt the steam to the turbine, is operated using a hydraulic servo actuator. In power plants, the performance of servo actuators is degraded by the air generated from the hydraulic system, or causes frequent failures owing to an increase in the wear of the seal. This is due to the seal being burnt as generated heat using the produced compressed air. Some power plants have exhausted air using a fixed orifice, and thus they encounter power loss due to mass flow exhaust. Failures are generated in hydraulic pumps, electric motors, and valves, which are frequently operated. In this study, we perform modeling and analysis of the load-sensing air-exhaust valves, which can be passed through very fine flow under normal use conditions, and exhaust mass flow air at the beginning stage as with existing fixed orifices. Then, we propose a method to prevent failures due to the compressed air, and to ensure the control accuracy of hydraulic servo actuators.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.210-210
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• 2013

그래핀은 뛰어난 기계적, 화학적, 광학적, 전기적 특성을 가지고 있는 2차원 물질로, 대면적 합성법과 전사 공정을 통해 다양한 기판에서의 사용이 가능해지면서 차세대 전자 소자로 활용하기위한 활발한 연구가 이루어지고 있다. 디스플레이, 태양전지의 전극과 전계 효과 트랜지스터의 채널로 적용한 연구에서 우수한 결과들을 보이고 있다. 특히, 금속/금속 산화물 전극은 염료 감응형 태양전지와 유기 발광 다이오드 구조에서 화학적으로 불안정할 뿐 아니라 일함수가 고정되어 쇼트키 접촉이 형성되면 저항을 낮추기 어렵지만, 그래핀은 금속/금속 산화물 전극보다 화학적으로 안정하고 일함수의 조절이 가능해 옴 접촉 형성에 용이하다. 그래핀의 일함수를 조절하는 연구는 크게 공유결합과 비공유 결합을 이용한 방법이 시도된다. 공유 결합을 이용한 방법은 합성과정에서 그래핀의 구조에 내재된 결함 혹은 새로운 결함을 형성하여 다른 원소를 첨가하는 방법이다. 이러한 방법은 그래핀의 결함 영역에서 작용하기 때문에 그래핀 전자 구조의 높은 수준 조절을 위해선 그래핀 구조의 파괴가 동반된다. 반면, 비공유 결합을 이용한 방법은 전하 이동 도핑 효과를 이용해 그래핀의 전자 구조를 제어하는 방법으로, 금속/금속산화물/기능기와 그래핀의 적층으로 복합 구조를 형성하는 방법이다. 금속/금속 산화물과의 복합구조는 안정적인 p-형 도핑이 보고되었지만, n-형 도핑은 대기중의 수분, 산소 그리고 기판과의 상호작용에 의해 대기중에서 불안정해 추가적인 피막공정이 요구된다. 기능기를 이용한 적층 구조는 그래핀과 기판사이의 상호작용 혹은 그래핀 전자 구조를 다양한 기능기를 이용해 제어하는 것으로, 이극성을 가진 자기정렬 단일층(self-assembled monolayers)이 대표적인 방법이다. 공간기(spacer)의 길이나 말단기(end group)의 종류로 p-형과 n-형의 도핑 수준을 제어할 수 있지만, 흡착기(chemisorbing groups)의 반응성이 기판의 화학적, 물리적 표면상태에 의존하기때문에 기판 선택이 제약되며 전처리 공정이 요구될 수 있는 한계가 있다. 본 연구에서는 다양한 기판에 적용가능한 용액 공정을 이용해 그래핀과 고분자를 적층하였고, 안정적이고 효과적으로 일함수를 낮추는 구조를 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.1
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• pp.66-75
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• 2000

In this paper, we present the efficient image transmission system using designed source-channel combined coder in W-CDMA mobile communication system. In proposed schemes, we decompose the wavelet transformed hierarchical band-images into some types of different size blocks which have different properties in error sensitivity. The RS(Reed-Solomon) coder with different coding rate is used for each decomposed source blocks which has different importance. In addition, we combine retransmitted error frames in Truncated Hybrid Type I ARQ. The proposed algorithm shows efficient image transmission methods because it is not much degraded in PSNR compared with the existing not combined source-channel coder in erroneous wireless channel.