• 한국컴퓨터정보학회논문지
• /
• 제21권3호
• /
• pp.39-45
• /
• 2016

In this paper, we propose a log management service model for efficient developments of android applications. The proposed model consists of two major parts which are the log collector and the log manager service. The log collector can capture the log information of a target application without modifications, because the collector is composed by aspect-oriented programming. The collected logs are transformed to chunk of data, and the chunk of data is sent to the log management service. The log management service is an android service component and an independent application in another process. So, the log management service can reduce the workload of logging in the target application. Through a case study, we show that the proposed log management service model can reduce the log processing time compared to other models without modifications of a target application.

• 조명전기설비학회논문지
• /
• 제25권7호
• /
• pp.83-91
• /
• 2011

Even if smoke, fumes, mist or dust particles are removed by electrostatic precipitators (ESPs), the occurrence of ozone, which is harmful to human body, has to be severely restricted in the indoor environments of hospitals, offices, and workshops. Therefore, the two-stage ESP generating positive corona at the ionizer is typically used because it creates less ozone than the two-stage ESP generating negative corona at the ionizer. In order to predict the collection performance and the optimal design of the two-stage ESP applied to positive high-voltage, particle concentration is experimentally investigated in this paper. In addition, particle motion within the collector section is also numerically analyzed. The positive corona discharge current of the ionizer is found to be affected by the applied voltage in the collector section but less so by the particle concentration. Particle concentration shows a minimum near the high voltage electrode of the collector section. The minimum value of the collection efficiency is almost proportional to gas velocity. When the collector length decreases, the minimum value of the collection efficiency increases. Charged particles entering the collector region are linearly deflected towards the grounded plate by an electric field. From the above experimental and numerical results, two empirical equations on the concentration ratio and the collection efficiency are derived, and are in good agreement with the experimental data.

• 대한기계학회논문집
• /
• 제8권6호
• /
• pp.517-525
• /
• 1984

본 연구에서는 2개의 축적탱크와 외부 열교환기로 구성된 가정용 태양열 급탕 시스템을 시뮬레이션 모델로 이론적인 해석을 하고 설계인자들의 값들을 변화시킴으로 써 각각의 성능을 계산할 수 있었다. 또 이 성능 계산치에 의하여 최적설계 인자치 들을 구할 수 있었다. 또한 1983년 1년간 서울지방의 매 시간 일분량과 기온을 사용 하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.187-187
• /
• 2007

This paper presents the electrical properties of SiGe HBTs designed with bottom collector and single metal layer structure for RF power amplifier. Base layer was formed with graded-SiGe/Si structures and the collector place to the bottom of the device. Bottom collector and single metal layer structures could significantly simplify the fabrication process. We studied about the influence of SiGe base thickness, number of emitter fingers and temperature dependence (< $200^{\circ}C$) on electrical properties. The feasible application in 1~2GHz frequency from measured data $BV_{CEO}$ ~10V, $f_r$~14 GHz, ${\beta\simeq}110$, NF~1 dB using packaged SiGe HBTs. We will discuss the temperature dependent current flow through the e-b, b-c junctions to understand stability and performance of the device.

• 에너지공학
• /
• 제22권2호
• /
• pp.112-119
• /
• 2013

태양열 에너지는 우리나라의 전체 에너지에서 차지하는 비율은 아직 미미하지만, 근래 이 분야에 대한 연구가 활발히 이루어지고 있다. 본 연구는 외부 날씨의 영향을 받지 않고 실내에서 안정적으로 태양열집열기에 관한 실험을 수행할 수 있는 태양열집열기 성능검사 시스템을 구축하고 새로운 형태의 태양열집열기를 연구 개발하기 위한 기초자료를 얻는데 있다. 이를 위해 태양열집열기 성능검사 시스템에 대한 CATIA 설계 및 제작을 거쳐 성능검사를 실시하였으며, 본 시스템에 장착된 이중진공관 집열기에 대한 수치해석을 수행하였다. 실험 결과 태양열집열기 성능검사 시스템의 설정온도차(${\Delta}T$)의 증가에 따라 작동회수는 감소하지만 총 작동시간은 모든 경우에 거의 동일함을 알 수 있었다. 또한 수치해석 결과 태양열흡수부의 온도가 높을수록 집열기 중심에서의 온도 감소율이 증가하는 것을 알 수 있었다.

• 대한전자공학회논문지SD
• /
• 제40권6호
• /
• pp.384-392
• /
• 2003

집적회로용 NPN BJT의 베이스-컬렉터간 역방향 항복전압 추출 알고리즘을 제시한다. 모의실험 시간을 최소화할 수 있는 3차원 메쉬 생성 방법을 제시하고 포아송 방정식의 해를 이용하여 역방향 항복전압을 구하는 방법을 제시한다. 제시된 방법의 타당성을 검증하기 위해 20V 공정과 30V 공정을 기반으로 제작된 집적회로용 NPN BJT의 베이스-컬렉터간 역방향 항복전압을 실측치와 비교한 결과 20V 공정을 이용한 NPN BJT는 8.0%의 평균상대오차를 보였으며 30V 공정을 이용한 NPN BJT는 4.3%의 평균 상대오차를 보였다.

• Wind and Structures
• /
• 제31권1호
• /
• pp.21-29
• /
• 2020

The wind field measurement of severe winds such as hurricanes (or typhoons), thunderstorm downbursts and other gales is important issue in wind engineering community, both for the construction and health monitoring of the wind-sensitive structures. Although several wireless data transmission systems have been available for the wind field measurement, most of them are not specially designed for the wind data measurement in structural wind engineering. Therefore, the field collection is still dominant in the field of structural wind engineering at present, especially for the measurement of the long-term and high-frequency wind speed data. In this study, for remote wind field measurement, a novel wireless long-term and high-frequency wind data acquisition system with the functions such as remote control and data compression is developed. The system structure and the collector are firstly presented. Subsequently, main functions of the collector are introduced. Also novel functions of the system and the comparison with existing systems are presented. Furthermore, the performance of this system is evaluated. In addition to as the wireless transmission for wind data and hardware integration for the collector, the developed system possesses a few novel features, such as the modification of wind data collection parameters by the remote control, the remarkable data compression before the data wireless transmission and monitoring the data collection by the cell phone application. It can be expected that this system would have wide applications in wind, meteorological and other communities.

• 한국인터넷방송통신학회논문지
• /
• 제16권4호
• /
• pp.89-96
• /
• 2016

본 논문에서는 데이터수집을 위한 MDC(mobile data collector) 기반의 무선센서네트워크를 고려한다. 이러한 네트워크에서는 MDC들이 이동하며 주위환경으로부터 데이터를 수집한 후 싱크노드에게 전달한다. 단일 MDC를 사용하는 기존 방식에서는 높은 데이터 수집 지연 문제가 발생한다. 복수의 MDC를 사용하는 일부 기존 방안에서는 네트워크 수명최대화에 초점을 두고 데이터 전달 지연에 대한 고려는 하지 않았다. 기존 방안의 이러한 제약을 극복하기 위하여 본 논문에서는 MDC의 개수가 주어진 상황에서 패킷지연을 최소화하는 문제와, 최대 허용 패킷 지연이 주어진 상황에서 필요한 MDC의 수를 최소화 하는 문제를 고려한다. 이를 위해서 두 개의 최적화 문제가 구성되었으며 MDC들의 이동거리와 이동시간 추정 모델을 개발하였다. Interior-point 알고리즘을 이용하여 최적화 문제에 대한 해를 구했으며, 제안된 방안을 검증하기 위한 수치결과와 분석을 제시하였다.

• 한국태양에너지학회 논문집
• /
• 제22권1호
• /
• pp.67-72
• /
• 2002

Solar Air Systems (SAS) have unique advantages for space heating and tempering ventilation air. Air, unlike water, needs no protection against freezing nor are leaks damaging to the building structure or its contents. In contrast to glazed collector, unglazed steel solar collector may have higher efficiencies over glazed flat collector due to the absence of the glass. Therefore, the monitoring of SAS is so important to evaluate actual performance of SAS for right applications. This study is to provide a testing method with a movable test cell developed in KIER to evaluate the thermal performance of SAS based on international standard method ASHRAE 93-86, "Method of Testing to Determine the Thermal Performance of Solar Collectors". The monitoring tool used advanced technique LabVIEW 6i with portable notebook computer. Sample results have been obtained to access the performance of a reference and a target SAS module. The process and tool introduced here could be used to provide a performance verification data for future implementation study applications.

• 한국전기전자재료학회논문지
• /
• 제20권8호
• /
• pp.661-665
• /
• 2007

This paper presents the electrical properties of SiGe HBTs designed with bottom collector and single metal layer structure for RF power amplifier. Base layer was formed with graded-SiGe/Si structures and the collector place to the bottom of the device. Bottom collector and single metal layer structures could significantly simplify the fabrication process. We studied about the influence of SiGe base thickness, number of emitter fingers and temperature dependence $(<200^{\circ}C)$ on electrical properties. The feasible application in $1{\sim}2GHz$ frequency from measured data $BV_{CEO}{\sim}10V,\;f_T{\sim}14GHz,\;{\beta}{\simeq}110,\;NF{\sim}1dB$ using packaged SiGe HBTs. We will discuss the temperature dependent current flow through the e-b, b-c junctions to understand stability and performance of the device.