• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.9
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• pp.795-801
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• 2014

STEP Cube Lab. classified as a pico-satellite has been being developed by SSTL(Space Technology Synthesis Laboratory) in Chosun University. Its main mission objective is to perform the on-orbit verification of core space technologies, which will be the potential candidates for future space missions. In this paper, to guarantee successful mission operation of the cube satellite under extremely severe space thermal environment condition, the system level thermal design and analysis has been performed. The effectiveness of the design has been verified through on-orbit thermal analysis of cube satellite.

• Journal of Aerospace System Engineering
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• v.18 no.2
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• pp.71-78
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• 2024

During the initial thermal design process, determining the thermal effect of various design variables in a complex orbital thermal environment is time-consuming. To save time in the initial design phase, it is necessary to quickly derive optimal design parameters and predict the temperature. To address these challenges, Veritrek, a software specialized in optimal design using a reduced-order model (ROM), was released in 2018. In this paper, we utilized the Veritrek software to build a reduced-order model, conduct sensitivity analysis, and perform optimal design analysis for a graphite sheet-based cryogenic cooler thermal control system. The goal was to determine the optimal design values for the number of graphite sheet layers, radiator area, and thickness that would meet the allowable temperature of the cryogenic cooler.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.11
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• pp.1072-1078
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• 2005

The present study has been conducted to tune a PID controller for large thermal systems such as a thermal environment chamber. In spite of large thermal mass of the thermal chamber under test, its response delay time was found to be negligible mainly due to high air recirculation rate. In general, heating and cooling capacities tend to be small compared the size of a thermal environment chamber, which leads to long transient periods of one hour or so. In the study, a PI tuning method is suggested which makes system responses faster while reducing overshoots and hunting by utilizing efficiently proportional band of actuators.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.887-894
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• 2016

The thermal control device using solid-liquid phase change material (PCM) is designed, manufactured, and experimented in thermal environment chamber. The n-Hexadecane is selected as a PCM and its melting point is placed within the component working temperature range. The PCM container is made of Al6061 and has the thermal spreading fins inside. To simulate the working condition for on-orbit satellite the heat pipes are used to connect the heater and radiator and the PCM thermal control device (PCMTD) is installed at the middle portion of heat pipes. The thermal buffer mass (TBM), which is same configuration and volume with PCMTD, is also manufactured to compare the thermal control performance. As a result, the PCMTD is not only more efficient than TBM in their temperature control features but both mass and power of compensation heater are reduced.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.7.1-7.1
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• 2009

세계 어디에서나 에너지의 수요가 급속히 증가하고 있는 반면, 인류가 사용 가능한 에너지 자원은 그 한계가 보이고 있다. 더욱이지구 온난화 현상이 표면화되어 있는 현 시점에서 인류의 사회활동은 환경문제와 밀접하게 연관되어져서 생각해야 한다는 것이 지구라는 close system 에서는 명확하다. 한정된 에너지 자원을 유용하게 사용하여 인류 미래의 삶을 보다 윤택하게 유지하기 위하여서는 사용목적에 맞는 최적의 에너지 형태로 효율 좋게 변환하는 것은 무엇보다도 중요하다. 열전기술은 원래우주개발 및 군사관계에 우선적으로 사용된 기술로써, 냉전시대의 미국과 소련이 개발경쟁을 한 바 있다. 열을 전기로 바꾸는 열전발전과 전기를 열로 바꾸는 냉동 보온의 양면으로부터 우주 탐사기에 탑재된 발전기, 잠수함용 냉난방장치, 비상용 전원, 자동차용 전원 등 가지각색의 system 이 고안되었다. 냉전시대가 끝나고 우주 군사 관계의 기술이 외부로 확산되게 되었으나 열전분야에서는 변환효율이 크지 않다는 단점으로 인해 민생부분으로 즉각적으로 전이할 수없는 어려운 점이 내재해 있었다. 에너지 및 환경의 문제가 심각히 대두되고 있는 오늘날에 이르러서야재료 및 그 응용에 대한 연구가 다시 붐을 이루어 활발히 진행되고 있다. 본 발표에서는 열전소재의 효율을 높이기 위한 고차나노구조 제어기술 및 그것을 이용한 최근의 연구결과들을 소개한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.6
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• pp.430-440
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• 2011

The purpose of this study was to investigate the interactions between the thermal factors in existing thermal control methods and to find out the control logic that can create more comfortable thermal conditions. For it, four thermal control logics were developed：conventional temperature-based control; temperature-based and humidity-based control; PMV-based control; and TS-based control. Their performance was comparatively tested in the U.S. typical 5-story office building in two climate zones (Detroit, Michigan and Miami, Florida) for two seasons (winter and summer) incorporating IBPT (International Building Physics Toolbox) and Matlab/Simulink. Analysis on the thermal conditions and energy efficiency revealed that each control logic created comfortable conditions for their respective target, i.e., temperature, humidity, PMV or TS, but uncomfortable for others (e.g., temperature-based control logic maintained PMV or TS uncomfortably or vise versa). In addition, energy efficiency was significantly different by logics. In conclusion, it can be said that the overall thermal comfort can be improved by the adoption of the PMV and TS as a target variable and their economical benefits are expected in the hotter climate zones with the reduced cooling and dehumidifying energy consumptions.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.141-142
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• 2019

본 논문에서는 Zigbee 네트워크 환경에서 Zigbee 라우터가 다양한 종류의 패킷을 전송받을 때 패킷의 종류에 따라 발생하는 처리 대기열의 처리 지연을 줄이기 위하여 각 종류의 패킷마다 서로 다른 대기열을 두고 라우팅하는 기법을 제안하였다. 이 전에는 네트워크 디바이스의 성능으로 인하여 대기열을 다루는 다양한 방법이 제안되었으나, 대기열을 분리하여 처리하는 방법에 대해서는 한계가 있었다. 본 논문에서는 패킷을 제어, 실시간, 일반 패킷으로 분류하여 이를 서로 다른 대기열에 수용하고 처리함으로써 패킷 종류에 따라 타 패킷에 발생하는 처리 지연을 줄여 네트워크 효율을 향상 시킨다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.05a
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• pp.287-291
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• 2003

현대의 선박운항에 있어서 선내 노동의 경감과 운항의 안정성 및 경제성 확보를 위하여 선박 자동화 및 원격 조종화가 이루어지고 있다. 또한, 선박조종 및 작업제어를 위하여 컴퓨터를 이용한 통합제어 시스템에 관한 연구도 활발하게 진행되고 있다. 그러나 소형선박 빛 어선과 같은 환경에서의 지능형 시스템에 관한 연구는 많이 부족한 실정이다. 인공지능기법을 이용하여 보다 인간 친화적인 시스템을 구현하고, 음성인식기술을 이용하여 원격으로 선박 조타기를 제어하여 조업자의 부담경감 및 인원절감의 효과를 가져올 수 있는 선박 조종시스템의 개발이 절실하다. 본 논문에서는 PC를 기반으로 하여 원격으로 모형 선박의 조타기를 제어하는 시스템을 구축하였다. 구체적인 연구 방법으로는, 음성인식기술과 지능형 학습 기법을 바탕으로 음성지시기반학습 시스템을 구축하고, 퍼지 조타수 조작모델을 구현하여 PC 기반 원격 제어시스템을 구현하였다. 또한, 구축된 원격 조타제어시스템을 축소된 선박모형(Miniature Ship) 시스템에 적용하여 그 효용성을 확인하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.235-242
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• 2017

A driving controller for active destruction protections can be applied to machinery, aerospace and military fields. In particular, this controller can be used to track and attack enemy flying objects through the active control. It is important to ensure reliability of the driving controller since its operation should be kept with precision to the target point. The temperature of the environment where the driving controller is used is about -32 C ~ 50 C (241~323 ). Heat generated in the driving controller should be maintained below a certain threshold (85 C (358 )) to ensure reliability; therefore, the study and analysis of the heat flow characteristics in the driving controller are required. In this research, commercial software Solid-Works Flow Simulation was used for the numerical simulation assuming a low Reynolds number turbulence model and an incompressible viscous flow. The goal of this paper is to design the driving controller safely by analyzing the characteristics of the heat flow inside of the controller composed of chips or boards. Our analysis shows temperature distributions for boards and chips below a certain threshold.

• Journal of Animal Environmental Science
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• v.15 no.2
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• pp.131-138
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• 2009

This study was conducted to find ways to control environment with the difference between body temperature and background temperature based on swine activity, and to apply to the environment control system of swine barns based on the findings. Following are the results. 1. Swine activity related to background temperature was achieved as color images and swine activity status was categorized into cold, comfortable, and hot periods with visualization system (thermal image system). 2. Thermal image system consisted of an infrared CCD camera, an image processing board - DIF (TH3100), an main computer (400Hz, 128M, 586 Pentium model) with C++ program installed. 3. Thermal image system categorizing temperatures into cold, comfortable, and hot was applicable to the environment control system of swine barns 4. Feed intake was higher in cold temperature, and finishing weight and weight gain per day in cold temperature were lower than others (p<0.05).