• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.1
• /
• pp.1-11
• /
• 1997

We examine the DS/SSMA system which is employing coherent BPSK with RAKE receiver. We adop Nakagami m-distribution as a multipath fading model. First, we analyze the performances of the system in the single cell environment and obtain the other-cell interference according to power control error. And considering the other-cell interference into the analysis of single cell system, we examine the cellular CDMA network. The average BER and outage probability are the figures of merit that characterize the system performance. The required BER, 1E-3, and required outage probability are the figures of merit that characterize the system performance. The requeired BER, 1E-3, and required outage probability, 1% for the voice transmission is considered to acquire the capacity of system.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.12
• /
• pp.1784-1792
• /
• 2001

Numerical analysis on a parallel flow heat exchanger(PFHE) is performed using 2 dimensional turbulent porous modeling. This modeling can consider three-dimensional configuration of passage (flat tube with micro-channels), and the stability and accuracy of numerical results are improved. The geometrical parameters(e.g., the position of separators, inlet/outlet, and porosity of passages of a PFHE) are varied in order to examine the flow and thermal characteristics and flow distribution of the single phase multiple passages system. The flow non-uniformities along the paths of the PFHE are observed to evaluate the thermal performance of the heat exchanger. The location of inlet affects the heat transfer, and the location of outlet affects the pressure drop. The porosity with the optimum thermal performance is around 0.53.

• Agribusiness and Information Management
• /
• v.3 no.2
• /
• pp.17-32
• /
• 2011

Peru is South America's third largest country and enjoys an enormous amount of natural resources. However, However, very few business studies on Peruvian agriculture have been presented. The objectives of this study are to introduce the general status of Peruvian agriculture to Korean business circles and to promote agricultural business opportunities in Korea and Peru. Secondary data related to Peruvian agriculture are collected and analyzed to understand the current situation of Peruvian agriculture and to suggest an outlook for business opportunities. Findings show that Peru will be a lucrative market for Korean agri-business to target in the near future and it is time for a proactive advance in agriculture by Korean business.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2002.05a
• /
• pp.205-209
• /
• 2002

인체의 피부온도는 쾌적성과 감성에 크게 영향을 미치며 의류의 개발이나 건축환경의 설계 등에 활용되고 있다. 단순히 몇몇 측정점에서의 피부온도 데이터가 아니라 인체표면에 걸친 온도분포를 파악함으로써 다양한 정보를 이용하여 보다 광범위한 응용분야에 활용될 수 있을 것이다. 현재 인체표면의 온도분포를 측정하기 위하여 대부분 적외선 열화상 카메라를 활용하고 있다 그러나 열화상 카메라는 서미스터 등을 이용한 피부온 센서에 비하여 온도분해능이 떨어지며 특히 의복내의 피부온을 측정하는 것이 불가능하고 노출된 인체표면에 대해서만 측정이 가능하다. 따라서 본 연구에서는 피부온 센서를 이용한 인체표면 온도분포 측정시스템을 개발하기 위하여 각 센서의 위치와 간격, 그리고 인체 곡면을 따라서 보간법에 따라 온도분포 결과에 미치는 영향을 파악하고 적외선 화상 결과와 비교하고자 한다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2001.11a
• /
• pp.211-215
• /
• 2001

실내나 의복내 열적쾌적성을 평가하기 위해서는 정밀하고, 안정성이 높으며 빠른 응답특성을 갖는 센서와 측정시스템이 필요하다. 더욱이 의복내의 온도를 측정하기 위해서는 소형, 경량으로 인체에 부착하기 쉬워야하며 측정기의 부착이 피험자에게 부담을 주어서는 안된다. 본 연구에서는 이러한 요구사항을 만족할 수 있으면서도 이동이 자유롭고 장시간 측정이 가능한 큰 Data 저장용량, 실시간 측정 기능, 손쉬운 온습도 변환장치등을 갖춘 의복내 및 실내 온습도 측정등의 다양한 분야에 활용이 가능한 온습도 측정기와 이에 필요한 센서를 개발하고 개발된 측정기의 선형특성을 평가하였다.

• Journal of the Korean Society for Heat Treatment
• /
• v.2 no.2
• /
• pp.1-10
• /
• 1989

In this study, the specimens of SCM 22 H steel were quenched in oil and water baths at various agitation conditions in order to investigate the effects of quenchants and agitation conditions on the quench-hardening. A multi-channel temperature measurement apparatus was employed to obtain the cooling curves at several predetermined positions of specimens. Microstructural observation and hardness test were also carried out. Computer simulation of heat treating process was carried out using the modified finite difference method. Prediction of thermal history and hardness distribution by 2-dimensional computer analysis was in good agreement with the experimental results. It was found that the quantitative design of heat treating process can be made by the computer aided heat-treating analysis.

• Proceedings of the KIEE Conference
• /
• 1987.11a
• /
• pp.193-196
• /
• 1987

We reported that hot electron phenomena in submicron nMOSFET by Monte Carlo method. In order to predict the influence of the hot electron effects on the device reliability, either simple analytical model or a complete two dimensional numerical simulation has been adopted. Results of numerical simulation, based on the static mobility model, may be inaccurate when gate length of MOSFET is scaled down to less than 1um. Most of device simulation packages utilize the static nobility model. Monte Carlo method based on stochastic analysis of carrier movement may be a powerful tool to characterize hot electrons. In this work, energy and velocity distribution of carriers were obtained to predict the relative degree of short channel effects for different device parameters. Our analysis shows a few interesting results when $V_{ds}$ is 5 volt, average electron energy does not increase with gate bias as evidenced by substrate current.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.4A
• /
• pp.345-355
• /
• 2011

This paper introduces the coded cooperation protocol in wireless relay network. We propose a two relay based coded cooperation protocol with RCPC codes for wireless networks. The proposed two-relay based system can achieve a diversity of order 4 under slow fading environment. Under fast fading, the diversity order is 2 times of the free distance of the convolutional code. We develop upper bounds on BER and FER for the system under both slow and fast fading with Rayleigh distribution. The effect of various channel conditions on the cooperation is also examined in this work.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.2 no.4
• /
• pp.303-315
• /
• 1990

Uniformity of velocity is quite important design points of a vertical laminar flow type clean room. In the present paper, flows in a room with a bottom pannel are numerically simulated by using a low-Reynolds number $k-{\epsilon}$ model, and a new flow model of the pannel are suggested. Resistance coefficient of the pannel and size of the exhaust channel show considerable effects on flow pattern and uniformity of flow on the bottom. Reflection coefficient also has important roles. A possibility to obtain the uniform and unidirectional flow is tested by adjusting the distribution of resistance coefficient of the pannel. Such a numerical simulation of the flow will be a good method to get optimun design parameters.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2007.06a
• /
• pp.349-352
• /
• 2007

Estimating the physical properties of the survey area and mapping the geotechnical basement play an important role in ocean engineering and construction field. In this study, we performed marine seismic reflection and refraction survey as an engineering application at shallow marine. We made use of the dual boomer - single channel streamer as a source-receiver in reflection seismic survey and air-gun source - the manufactured OBC(Ocean Bottom Cable)-type streamer in refraction survey. In the seismic reflection data, we could easily find the geological layers and basement. Moreover, seismic refraction data could present sediment thickness and velocity distribution.