• KIEAE Journal
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• v.12 no.4
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• pp.97-104
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• 2012

A phase-change material is a substance with a high heat of fusion which, melting and freezing at a certain temperature, is capable of storing and releasing large amounts of energy. Heat is absorbed or released when the material changes from solid to liquid. Therefore, PCMs are classified as latent heat storage (LHS) units. The purpose of this study is to analyze PCM wallboard design parameters using dynamic energy simulation. Among the factors of PCM, melting temperature, latent heat, phase change range, thermal conductivity are very important element to maximize thermal energy storage. In order to analyze these factors, EnergyPlus which is building energy simulation provided by department of energy from the U.S is used. heat balance algorithm of energy simulation is conduction finite difference and enthalpy-temperature function is used for analyzing latent heat of PCM. The results show that in the case of melting temperature, the thermal energy storage could be improved when the melting temperature is equal to indoor surface temperature. It seems that when the phase change range is wide, PCM can store heat at a wide temperature, but the performance of heat storage is languished.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.10a
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• pp.281-286
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• 1998

본 논문에서는 상변화형 미세캡슐 함유량이 다른 세 개의 축열보드의 열성능 특성에 관해서 다루었다. 상변화 물질로는 CH3COONa·3H2O를 사용했고 이러한 물질의 미세캡슐을 시멘트 몰타르와 혼합하여 축열보드를 제작하였다. 결과를 보면 상변화형 미세캡슐 향유량이 20%인 경우가 0%인 경우보다 유효도에서 10%가 더 높았고 냉각온도가 낮을수록 주기시간은 짧아지고 방출열량은 증가를 하였다.

• The Journal of the Acoustical Society of Korea
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• v.14 no.1E
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• pp.83-87
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• 1995

The implementation of the voice dodec is imjplemented by using TMS320C30, which is the floating point DSP chip from Texas Instrument. QCELP (Qualcomm Code Excited Linear Prediction) is used to encode and decode the voice. The QCELP code is implemented by the TMS320C30 C-dode. The DSP board is controlled by the PC. The PC program tranfors the voice file from and to the DSP board, which is also implemented by C-code. The voice is encoded by the DSP board and the encoded data is transferred to PC to be stored as a file. To hear the voice. the voice data file is sent to DSP board and decoded to synthesize audible voice. Two flags are used by both programs to notify the status of the operation. By checking the flags, DSP and PC decides when the voice data is transferred between them.

• Solar Energy
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• v.19 no.3
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• pp.23-28
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• 1999

The thermal performance of storage brick, containing microencapsulated PCM(phase change material), was investigated for utilization as a floor heating system. Sodium acetate trihydrate($CH_3COONa{\cdot}3H_2O$) was selected for the PCM and was encapsulated. The thermal storage brick was manufactured with mixing cement mortar having 10%, 20% PCM contents, respectively. Four different flow rates and three different cooling temperatures was used in this work for analyzing the heat charging and discharging characteristics of the thermal storage brick. The result showed that cycle time was shortened as the PCM content was increased and as the mass flow rate was increased. The same effect was obtained when the cooling temperature was decreased. For each thermal storage brick the overall heat transfer coefficient(U-value) was constant for a 0% brick, but was increased with time for the bricks containing microencapsulated PCM.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.162-167
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• 2011

Thermal storage plays an important role in building energy saving, which is greatly assisted by the incorporation of latent heat storage in building materials. A phase change material is a substance with a high heat of fusion which, melting and solidifying at a certain temperature, can be storing and releasing large amount of energy. Heat is stored or released when the material changes from solid to liquid. Integration of building materials incorporating PCMs into the building envelope can result in increased efficiency of the built environment. The aim of this research is to identify thermal performance of PCMs impregnated building materials which is applied to interior of building such as gypsum and red clay. In order to analyze thermal performance of phase change materials, test-cell experiments and simulation analysis were carried out. The results show that micro-encapsulated PCM has an effect to maintain a constant indoor temperature using latent heat through the test-cell experiments. PCM wallboard makes it possible to reduce the fluctuation of room temperature and heating and cooling load by using EnergyPlus simulation program. Phase change material can store solar energy directly in buildings. Increasing the heat capacity of a building is capable of improving human comfort by decreasing the frequency of indoor air temperature swings so that the interior air temperature is closer to the desired temperature for a long period of time.

• Journal of Digital Convergence
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• v.18 no.11
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• pp.241-246
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• 2020

In this paper, we propose a neural network model to converge the marine electric propulsion system and deep learning algorithm to predict the DC/DC converter output current in the electric propulsion regeneration system and to predict the battery charge during regeneration. In order to experiment with the proposed neural network, the input voltage and current of the PCM were measured and the data set was secured on the prototype PCM board. In addition, in order to improve the learning results in the insufficient data set, the scale of the data set was increased through data fitting and its learning was executed further. After learning, the difference between the data prediction result of the neural network model and the actual measurement data was compared. The proposed neural network model effectively showed the prediction of battery charge according to changes in input voltage and current. In addition, by predicting the characteristic change of the analog circuit constituting the DC/DC converter through a neural network, it is determined that the characteristics of the analog circuit should be considered when designing the regeneration system.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.570-574
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• 2010

The main function of conventional insulation materials is only to block the heat transfer and reduce heat loss from the building. On the other hand, thermal storage materials can work as an energy saver by absorbing or emitting heat within a specific temperature range. Thermal storage materials for building can maintain a constant temperature by effectively regulating the cycle of indoor temperature. As a result, we can enhance the performance of a cooling and heating system efficiently. In this study, phase change materials (PCMs) were added as thermal storage materials into gypsum boards which are extensively used for building material and we found out the thermal environmental characteristics. In addition, we checked out some problems when applying the thermal storage materials to buildings. Finally, This study set out to examine the degree of environmental-friendly characteristics of thermal storage building materials by analyzing the amount of TVOC and HCHO contents with the possibility of pollutants emission.

• The Journal of the Acoustical Society of Korea
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• v.12 no.1
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• pp.27-36
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• 1993

FM방식의 악기음원합성은 해당 악기의 음색과 음정에 맞는 FM의 기본 주파수와 변조 계수를 정하여 신호 파형을 생성하는 것으로, 다른 가, 감산방식 또는 PCM방식 등에 비해 비교적 간단한 구조로 다양한 악기음원합성이 가능하다. 따라서 현재 사용되고 있는 개인용 컴퓨터에 부착되는 사운드합성 카드에는 FM방식 음원합성기술이 적용되고 있다. 본 논문에서는 FM방식 음원합성기술을 이용하여 실시간 악기음원합성이 가능한 논리회로를 설계하는데 관한 연구를 기술한다. 본 연구에서는 소프트웨어 프로그래밍에 의해 FM방식 음원합성기의 구조를 설계하고 주요 블록의 최적 변수 값을 실험하였다. 논리회로 설계 및 회로검증은 향후 주문형반도체(ASIC:Application Specific Integrated Circuit)제작을 위해 기존의 표준셀 라이브러리와 주문형반도체 전용 설계시스템을 사용하였다. 회로검증 결과는 간이 평가보드를 제작하고 PC와 접속시켜 생성된 악기음을 직접듣는 주관적 평가방법으로 최종 확인하였다.

• Annual Conference of KIPS
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• 2020.05a
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• pp.142-145
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• 2020

캐시 부채널 공격은 캐시 기반의 공격 기법으로 개인정보 유출에 대한 위험성이 큰 보안 취약점이다. 해당 취약점을 막기 위해 실시간 공격 탐지 기법에 관한 연구들이 진행되고 있지만 사용자에게 이벤트값과 탐지 결과를 빠르고 편리하게 보여줄 필요성이 있다. 본 논문은 효율적인 캐시 부채널 공격 탐지를 위해 Intel PCM 과 기존의 탐지프로그램을 개선하여 탐지에 필요한 데이터들을 실시간으로 모니터링 및 경고를 보내주는 프레임워크를 제작했다. 해당 프레임워크는 캐시 부채널 공격을 실시간 탐지 및 관련 데이터들을 대시보드로 보여준다.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.107-115
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• 2011

The line-telemetry data processing system is necessary for monitoring the status of each onboard systems of KSLV-I upper stage during the ground tests and launch preparation. The mission of line-telemetry system is to provide reference telemetry data and to monitor the status of upper stage. The line-telemetry data processing system consists of a PCM acquisition/processing server, a system management server, and 9 monitoring consoles. In this paper, we will describe the overview of onboard remote measurement system, the design of the line-telemetry data processing system, anomaly setup information for indicating alarm signal in case of abnormal occurrence, and the result of the ground test and flight test.