• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.23-30
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• 2009

A new high performance and low cost unified power system is proposed through investigating conventional Power-Integrated Drive(PID) system and Power-Separated Drive(PSD) system applied to LCD TV. Since the proposed system consists of two stage, namely power and inverter stage it features high efficiency and cost effectiveness. To satisfy the safety standard of the High voltage transformer, 1:1 transformer is employed between inverter and high voltage transformer. Moreover, to ensure the Zero Voltage Switching(ZVS) of all power switches and the Pulse Count Modulation(PCM) method is employed, which controls the number of pulse at the fixed frequency and fixed duty cycle. Therefore, it features high efficiency, improved heat generation, cost effectiveness and good EMI performance including no additional current balancing coil. To confirm the validity of proposed system, comparison of conventional system, verification of experimental results are presented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.113-120
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• 2010

Recently, various evaluations concerning structural stability under construction step and completely constructed step have been executed during a Long-span Arch Bridge designing procedure. However, the breakage of cable-hangers of arched bridge in unexpected accident or periodic cable-replacement has not been considered. Therefore, the purpose of this study is that analyzing structural safety of arched bridge when the cable-hangers being fractured by that reasons. Dynamic analysis are performed by idealizing impact load to three types of impact functions as fracturing the cables. Consequently, when the hangers are fractured, the maximum tensile force by dynamic analysis is larger than those by static analysis. Therefore, the dynamic analysis is demanded to accurately obtain the responses for the structural stability with a realistic impact loading model in the breakage and replacement of cable hangers of long-span arched bride. Moreover, the analysis method and results in this study can be used to basic criteria in design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.75-82
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• 2008

There are almost 18,000 dams including about 1,200 large dams in Korea. The large dams are well operated and maintained by KWATER(Korea Water Resource Corporation), KRC(Korea Rural Community & Agriculture Corporation) and KHNP(Korea Hydro & Nuclear Power Co., Ltd.). Several research reports concern with the safety of these large dams are presented but there is no paper concerned with small dams which has diversion tunnel through the dam body. The purpose of this study is to show the common defects of small dams according to various cases of degradation of dams and the repair and retrofit methods which applied to the damaged dams. And this study performed resistivity survey to evaluate the effect of retrofitting dam. Also, this study tries to present the solution which concerned with these common defects in maintenance and design steps.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.122-129
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• 2013

In this study, the risk factors which derive from the ground condition of typical construction sites are put forward. In order to prioritize the risk elements, the analytical method of AHP was used. The result of using a weighting factor for each risk analysis showed that if the constituency index is less than 0.1, then reliable results and priorities for each of the risk elements can be calculated using the AHP method. From now on, if the range of measured value can be established, the risk or safety value of concrete structures for power lines can be applicable.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.60-68
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• 2017

Since the bridge is the main facility of the road that is the core of the civil infrastructure, the bridge is constructed to ensure stability and serviceability during the traffic use. In order to secure the safety of bridges, evaluating the integrity of bridges at present is an important task in the maintenance work of bridges. In general, to evaluate the load carrying capacity of bridges, it is possible to confirm the superimposed behavior and symmetric behavior of bridges by estimating the lateral load distribution factor of the bridges through vehicle loading tests. However, in order to measure the lateral load distribution factor of a commonly used bridge, a static loading test is performed. There is a difficulty in traffic control. Therefore, in this study, the static displacement component of the bridge measured in the dynamic loading test and the ambient vibration test was extracted by using empirical mode decomposition technique. The lateral load distribution was estimated using the extracted static displacement component and compared with the lateral load distribution factor measured in the static loading test.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.138-147
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• 2018

With the recent series of damage caused by earthquakes in Korea, such as Gyeongju and Pohang, we know that Korea is no longer a safe zone for earthquakes and that we need to be prepared for them. In addition, bridges built prior to the introduction of seismic design concepts remain without adequate seismic reinforcement measures, and earthquake reinforcement should be performed efficiently considering economic and structural safety. Preliminary assessment of seismic performance of existing bridges is divided into four seismic groups, taking into account seismicity, vulnerability and Impact, considering the magnitude of the existing bridge's seismic, and prioritization for further evaluation of seismic performance. In this study, unlike the existing anti-seismic reinforcement priority method, scores are calculated based on the seismic design criteria applied to bridges, importance coefficient of the bridge including the zone coefficient and the Importance, vulnerability index of the bridge including the soil condition and the elapsed years, detail coefficient of the bridge including the superstructure form, the span length, the width, the height, the design load, and the daily traffic volume. The calculated score items will be weighted and grouped according to the results. Using this, a simpler and more efficient algorithm was proposed to determine the priority of seismic reinforcement on a bridge.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.89-96
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• 2018

Bridge structures are a socially important infrastructure and safety management of bridges during the public service period is important. Steel box girder bridges, which account for a large percentage of road bridges, have been designed by allowable stress design method(ASD) and load carrying capacity have been evaluated using ASD. Although design specification has recently been changed to limit state design method(LSD), in most cases, ASD is still used for load carrying capacity evaluation. In this study, the two design methods were used to compare the results of a load rating factor evaluation on a number of bridges, and we are going to find out how to convert the existing rating factor by ASD into rating factor by LSD. The results of this study are expected to can be used as a basis for determining the need for reinforcement and evaluating load carrying capacity by LSD in bridge maintenance.

• Proceedings of the KIEE Conference
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• 2004.05b
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• pp.186-191
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• 2004

전력계통에서 역률개선을 위해 사용하는 전력용 콘덴서(이하 SC bank)는 전력계통의 운전상 전압 제어와 역율개선이라는 두가지 측면에서 매우 중요한 전력설비이다. 또한 최근에 전력산업 구조조정에 의해 발전분야가 분할되는 시점에서 SC bank의 역할의 중요성이 강조되고 있다. 본 논문에서는 SC의 고장원인이 무엇인지를 현장조사를 통해 수행하였다. 그 결과 SC bank를 구성하고 있는 리액터, 콘덴서, PT, 혹은 CT 흑은 방전코일의 열화원인이 대부분 차단기의 투입서지와 차단서지에 의해 발생되고 있음을 확인하였다 또한 기존의 보호시스템은 SC Bank의 보호에 적합하지 않음을 검토하였다 차단기 서지에 대한 대책으로는 투입시 전압영점투입과 중성점 저항기의 취부로 투입서지 및 차단서지를 효과적으로 감소되는 현상을 모의와 현장실측을 통해 확인하였다. 또한 기존의 보호방식이 과전류와 과전압 부족전압 혹은 CT와 PT를 이용한 차동방식에 의해 셀의 경련변화를 감지하고 있으나 이 경우 보호맹점이 존재하게 됨을 검토하였다. 이러한 보호상의 문제점을 보완하는 방법으로 SC bank는 임피던스가 늘 일정하는 점에 착안하여 전압과 전류를 이용하여 임피던스의 변화량을 감시하고, 또 한가지 방법은 SC bank의 운전특성상 무효전력만을 발생시킨다는 점에 착안하여 만일 유효전력 성분이 SC bank에서 감지된다면 소자의 이상이나 비정상적은 전류경로가 된다는 결론에 도달하고 유효전력감시를 통한 SC bank의 열화감지가 가능하다는 결론에 도달하였다. 본 논문에서 제안한 3가지의 방법, 즉, 첫째 영점투입차단기 채택, 둘째, 중성점 저항기의 도입, 셋째 새로운 보호방식에 의한 기존의 보호맹점의 보완을 제안하였다. 위의 새로운 제안을 현장에 적용하는 경우 제작사의 제작불량을 제외한 운전상의 SC bank의 문제점 및 고장빈도는 현저히 감소하게 될 것으로 사료된다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.181-185
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• 2020

Hazardous and noxious substance (HNS) detection sensors were fabricated using multi-walled carbon nanotubes (MWCNTs) and various binder materials for ion batteries. To obtain uniformly printed films, the printing precision according to the substrate cleaning method was monitored, and the printing paste mixing ratio was investigated. Binders were prepared using styrene butadiene rubber + carboxymethyl cellulose (SBR+CMC), polyvinylidene fluoride + n-methyl-2-pyrrolidene (PVDF+NMP), and mixed with MWCNTs. The surface morphology of the printed films was examined using an optical microscope and a scanning electron microscope, and their electrical properties are investigated using an I-V sourcemeter. Finally, sensing properties of MWCNT printed films were measured according to changes in the concentration of the chemical under the various applied voltages. In conclusion, the MWCNT printed films made of (SBR+CMC) were found to be feasible for application to the detection of hazardous and noxious chemicals spilled in seawater.

• Genomics & Informatics
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• v.11 no.4
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• pp.211-217
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• 2013

Many biobanks were established as biorepositories for biomedical research, and a number of biobanks were founded in the 1990s. The main aim of the biobank is to store and to maintain biomaterials for studying chronic disease, identifying risk factors of specific diseases, and applying personalized drug therapies. This report provides a review of biobanks, including Korean biobanks and an analysis of sample volumes, regulations, policies, and ethical issues of the biobank. Until now, the top 6 countries according to the number of large-scale biobanks are the United Kingdom, United States, Sweden, France, the Netherlands, and Italy, and there is one major National Biobank of Korea (NBK) and 17 regional biobanks in Korea. Many countries have regulations and guidelines for the biobanks, and the importance of good management of biobanks is increasing. Meanwhile, according to a first survey of 456 biobank managers in the United States, biobankers are concerned with the underuse of the samples in their repositories, which need to be advertised for researchers. Korea Biobank Network (KBN) project phase II (2013-2015) was also planned for the promotion to use biospecimens in the KBN. The KBN is continuously introducing for researchers to use biospecimens in the biobank. An accreditation process can also be introduced for biobanks to harmonize collections and encourage use of biospecimens in the biobanks. KBN is preparing an on-line application system for the distribution of biospecimens and a biobank accreditation program and is trying to harmonize the biobanks.