• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.4
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• pp.85-90
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• 2005

Inundation of Transformer Vault breaks out every summer season in low-tying downtown and low-tying shore by localized heavy rain, typhoon and tidal wave. In case inundation of Transformer Vault, it occurs a great economic loss owing to recovery time and events of electric shock occur by inundation electrical facility. So we need installation plan of Transformer Vault in common flood area for preventing from economic loss and equipment events. Therefore we research distribution of 22.9[kV] Transformer Vault in common flood of the country and analyze field condition about flood protection plan. And we analyze regulation or law relating to the flood protection counterplan of US, England, Australia. This paper will be used to present a reform proposal of electrical related law about flood protection of existing Transformer Vault. Also we present considering facts at the time Transformer Vault installation in common flood area.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.29-36
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• 2009

In this paper, the design and implementation of LNA and down-mixer using 90 nm CMOS process are presented for 60 GHz band WPAN receiver. In order to extract characteristics of the transistor used to design each elements under the optimum bias conditions, the S-parameter of the manufactured cascode topology was measured and the effect of the RF pad was removed. Measured results of 3-stages cascode type LNA the gain of 25 dB and noise figure of 7 dB. Balanced type down-mixer with a balun at LO input port shows the conversion gain of 12.5 dB within IF frequency($8.5{\sim}11.5\;GHz$) and input PldB of -7 dBm. The size and power consumption of LNA and down-mixer are $0.8{\times}0.6\;mm^2$, 43 mW and $0.85{\times}0.85\;mm^2$, 1.2 mW, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.746-752
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• 2020

As environmental issues have been taken seriously, the number of solar power generation facilities has rapidly increased in Korea. The voltage at the output stage of an inverter increases in a system that connects a small-capacity photovoltaic power generation to low-voltage power distribution. This degrades the quality of the low-voltage distribution system and adversely affects the load facility. In this study, a solution was obtained to increase the voltage at the output stage of the solar inverter according to the connection of the low-voltage distribution system. The voltage can be controlled by using reactive power factor control inverters. If the secondary tap is adjusted, the voltage can be adjusted to about 15 V, but there is a problem in that the tap is not adjusted unless the KEPCO distribution regulation voltage is out of the range of 220±13V. If the number of inverters is limited, the inverter can be started within the inverter overvoltage range. If it is connected to three phases, the voltage is distributed. The results indicated that power factor control and active voltage control inverters were easy to apply in the field.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.473-480
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• 2011

The proton exchange membrane (PEM) fuel cell system is critically dependent on the humidity, which should be properly maintained over the entire operating range. A membrane humidifier is used for the water management in the PEMFC because of the membrane humidifier's reliable performance and zero parasitic power loss. In the PEMFC system, the membrane humidifier is required to provide appropriate humidity for the design point of the fuel cell. Although the performance of the fuel cell depends on the performance of the humidifier, few studies have provided a systematic analysis of the humidifier. We carry out an experimental analysis of the membrane humidifier using a vapor condensation bottle. The dry air pressure, water flow temperature, and air flow rate were chosen as the operating parameters. The results show that the time constant for the dynamic response of the membrane humidifier is relatively short, but additional analysis should be carried out.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.1
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• pp.13-18
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• 2014

Sensor nodes are used for monitoring and collecting the environmental data via wireless sensor network. The wireless sensor network with various sensor nodes draws attention as a key technology in ubiquitous computing. Sensor nodes has very small memory capacity and limited power resource. Thus, it is essential to have energy efficient strategy for the sensor nodes. Since the sensor nodes are operating on the same frequency bands with ISM frequency bands, the interference by the devices operating on the ISM band degrades the quality of communication integrity. In this paper, the convolutional code is proposed instead of ARQ for the error control for the sensor network. The proposed convolutional code was implemented and the BER performance is measured. For the fixed transmitting powers of -19.2 dBm and -25dBm, the BER with various communication distances are measured. The packet loss rate and the retransmission rate are calculated from the measured BER. It is shown that the porposed method obtained about 9~12% and 12-19% reduction in retransmission rate for -19.2 dBm and -25 dBm respectively.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.62-62
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• 2003

과학위성 1호에는 위성의 임무를 수행하기 위하여 광학계, 구조부, 및 전자부 등 여러가지 부품들이 실장되는데, 그 중 전자부의 가장 중요한 부품 중의 하나인 인쇄회로기판(Printed Circuit Board, PCB)의 우주환경에서의 특성 대해서 논의하고자 한다. Solder Resistor(Solder Mask)의 화학성분이 위성체가 작동하는 우주환경에서 위성체 임무수행 시 발생할 수 있는 out-gassing으로 인해 위성체가 본연의 임무 실패라는 결과를 초래할 수 있다 NASA 및 ESA의 Out-gassing에 관한 규정과 TRW에 의한 KOMSAT에 사용된 재료의 진공상태의 Outgassing에 관한 내용에 의하면, 재료의 진공상태와 Out-gassing은 America Society for Testing and Materials에서 제시한 ASTM E959 기준에 따라 제작된다. 일반적으로 우주 환경에서 광학계나 전자부의 원활한 동작을 위해서는 인쇄 회로 기판의 총 질량손실(Total Mass Loss, TML)은 1.00%을 넘지 말아야 하며, 휘발성 응축 질량 (Collected Volatile Condensable Mass, CVCM)은 0.1% 미만이어야 한다. Total Mass Loss(TML) 방법은 대기중에서 측정한 질량과 진공 조건에서 변화되는 질량을 측정함으로써 진공조건에서의 탈기체 특성을 측정하는 방법이다. 본 연구에서는 Solder Resistor(Solder Mask)의 탈기체 측정을 위한 진공챔버의 측정방법 및 진공 형성 과정을 기술하고 실제 과학위성1호에 장착될 시료를 예로 들어 인쇄회로기판에 입힌 Solder Resistor(Solder Mask)가 우주환경인 진공상태에서 위성체 부품의 작동 시 발생할 수 있는 탈기체되는 정도를 질량의 변화분으로 측정하여 위성체가 우주 환경에서 본연의 임무를 안전하게 수행할 있는지를 검증하였다.부분이다.다.향을 해석하고 시뮬레이션 하였다.Device Controller)는 ECU로부터 명령어를 받아서 arm 및 safe 상태에 대한 텔리 메트리 데이터를 제공한다 그리고, SAR(Solar Array Regulator)는 ECU로부터 Bypass Relay 및 ARM Relay에 관한 명령어를 받아 수행되며 그에 따른 텔리 메트리 데이터를 제공한다. 마지막으로 EPS 소프트웨어를 검증하는 EPS Software Verification을 수행하였다 전력계 소프트웨어의 설계의 검증 부분은 현재 설계 제작된 전력계 .소프트웨어의 동작 특성 이 위성 의 전체 운용개념과 연계하여 전력계 소프트웨어가 전력계 및 위성체의 요구조건을 만족시키는지를 확인하는데 있다. 전력계 운용 소프트웨어는 배터리의 충ㆍ방전을 효율적으로 관리해 3년의 임무 기간동안 위성체에 전력을 공급할 수 있도록 설계되어 있다this hot-core has a mass of 10sR1 which i:s about an order of magnitude larger those obtained by previous studies.previous studies.업순서들의 상관관계를 고려하여 보다 개선된 해를 구하기 위한 연구가 요구된다. 또한, 준비작업비용을 발생시키는 작업장의 작업순서결정에 대해서도 연구를 행하여, 보완작업비용과 준비비용을 고려한 GMMAL 작업순서문제를 해결하기 위한 연구가 수행되어야 할 것이다.로 이루어 져야 할 것이다.태를 보다 효율적으로 증진시킬 수 있는 대안이 마련되어져야 한다고 사료된다.$\ulcorner$순응$\lrcorner$의 범위를 벗어나지 않는다. 그렇기 때문에도 $\ulcorner$순응$\lrcorner$과 $\ulcorner$표현$\lrcorner$의 성격과 형태를 외형상으로

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.83-97
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• 2018

Tunnels are widely used for special purposes including roads, railways and culvert for power transmission, etc. Its cross-section shape is determined by uses, ground condition, environmental or economic factor. Many papers with respect to behaviours of adjacent ground and existing structure tunnelling-induced have been published by many researchers, but tunnel cross-section have rarely been considered. A collapse of tunnel causes vaster human and property damage than structures on the ground. Thus, it is very important to understand and analyse the relationship between behavoiurs of ground and cross-section type of tunnel. In this study, the behaviour of ground due to tunnel excavation for underground station below the grouped pile supported existing structure was analysed through laboratory model test using a trap-door device. Not only two cross-section types, 2-arch and box, as station for tunnel, but also, offset between tunnel and grouped pile centre (0.1B, 0.25B, 0.4B) are considered as variable of this study. In order to measure underground deformation tunnelling-induced, Close Range Photogrammetry technique was applied with laboratory model test, and results are compared to numerical analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1276-1284
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• 1999

We have evaluated the BER's and CLP's of Wireless ATM (WATM) cells employing the concatenated FEC code with pilot symbols for fading compensation through the simulation in indoor wireless channel modeled as a Rayleigh and a Rician fading channel, respectively. The results of the performance evaluation are compared with those obtained by employing the convolutional code in the same condition. In Rayleigh fading channel, considering the maximum tolerance BER ( $10^-3$) as a criterion of the voice service, it is blown that the performance improvement of about 4 dB is obtained in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols rather than the convolutional code with pilot symbols.When the values of K parameter which means the ratio of the direct signal to scattered signal power in Rician fading channel are 6 and 10, it is shown that the performance improvement of about 4 dB and 2 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols considering the maximum tolerance BER of the voice service. Also in Rician fading channel of K=6 and K= 10, considering CLP = $10^-3$ as a criterion, it is observed that the performance improvement of about 3.5 dB and1.5 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.7
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• pp.76-84
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• 2013

In the passive emitter localization using instantaneous TDOA (time difference of arrival) and FDOA (frequency difference of arrival) measurements, the estimation accuracy can be improved by collecting additional measurements. To achieve this goal, it is required to increase the number of the sensors. However, in electronic warfare environment, a large number of sensors cause the loss of military strength due to high probability of intercept. Also, the additional processes should be considered such as the data link and the clock synchronization between the sensors. Hence, in this paper, the passive localization of a stationary emitter is presented by using the successive TDOA and FDOA measurements from two moving sensors. In this case, since an independent pair of sensors is added in the data set at every instant of measurement, each pair of sensors does not share the common reference sensor. Therefore, the QCLS (quadratic correction least squares) methods cannot be applied, in which all pairs of sensor should include the common reference sensor. For this reason, a Gauss-Newton algorithm is adopted to solve the non-linear least square problem. In addition, to show the performance of the proposed method, we compare the RMSE (root mean square error) of the estimates with CRLB (Cramer-Rao lower bound) and derived the CEP (circular error probable) planes to analyze the expected estimation performance on the 2-dimensional space.

• Journal of IKEEE
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• v.22 no.2
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• pp.495-498
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• 2018

In this paper, we propose an DAP system for dose evaluation of medical and industrial X-ray generator. Based on the DAP measurement technique using the Ion-Chamber, the proposed system can clearly measure the exposure radiation dose generated by the diagnostic X-ray apparatus. The hardware part of the DAP measures the amount of charge in the air that is captured by an X-ray. The high-speed processing algorithm part for cumulative radiation dose measurement through microcurrent measures the amount of charge captured by X-ray at a low implementation cost (power) with no input loss. The wired/wireless transmission/reception protocol part synchronized with the operation of the X-ray generator improves communication speed. The PC-based control program part for interlocking and aging measures the amount of X-ray generated in real time and enables measurement graphs and numerical value monitoring through PC GUI. As a result of evaluating the performance of the proposed system in an accredited testing laboratory, the measured values using DAP increased linearly in each energy band (30, 60, 100, 150 kV). In addition, since the standard deviation of the measured value at the point of 4 division was ${\pm}1.25%$, it was confirmed that the DAP showed uniform measurements regardless of location. It was confirmed that the normal operation was not less than ${\pm}4.2%$ of the international standard.