• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.74-76
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• 2007

In this paper a maximum power point tracking(MPPT) techniques for power of PV(photovoltaic) systems are presented using boost converter for a connected single phase inverter. On the basic principle of power generation for the PV module, algorithms for maximum power point tracking are described by utilizing a boost converter to adjust the output voltage of the PV module. Based on output power of a boost converter, single phase inverter uses predicted current control to control four IGBT's switch in full bridge. Furthermore a low cost control system for solar energy conversion using the DSP is developed, based on boost converter to adjust the output voltage of the PV module. The effectiveness of the proposed inverter system is confirmed experimentally and by means of simulation. Finally, experimental results confirm the superior performance of the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2456-2458
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• 2003

Recently, an automatic crane control system is required with high speed and rapid transportation. Therefore, when container is transferred from the initial coordinate to the finial coordinate, the container paths should be built in terms of the least time and without sway. Therefore, we calculated the anti-collision path for avoiding collision in its movement to the finial coordinate in this paper. And we constructed the neural network predictive two degree of freedom PID (NNPPID) controller to control the precise navigation. The proposed Predictive control system is composed of the neural network predictor, two degree of freedom PID(TDOFPID) controller, neural network self-tuner which yields parameters of TDOFPID. We analyzed crane system through simulation, and proved excellency of control performance over the conventional controllers.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 전기설비
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• pp.81-82
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• 2006

한국에 지중배전케이블이 설치된 지 30년이 넘고 현재 지중화율은 12% 가량 되고 있다. 지중화율이 점차 높아지는 추세에서 기존의 매설된 케이블이나 사고 케이블에 대한 교체로 철거케이블이 발생하는 빈도가 높아져 이를 쉽게 철거할 수 있는 방안이 필요하여 철거용 지중케이블 자동절단기 개발을 하기에 이르렀다. 케이블철거 작업이 현재까지는 대부분 수동유압절단기를 통하여 이루어지다보니 작업의 경제성이 상당히 낮고 안전상의 문제가 대두되어 관로내 케이블을 차량의 유압을 이용하여 자동 인출, 자동 절단할 수 있는 기기를 개발하기에 이르렀다. 자동절단기를 사용함으로써 기존 $4{\sim}5$명이 소요되는 작업이 $1{\sim}2$명의 인력으로도 작업할 수 있고 작업시간도 대폭 단축되어 경제성이 크게 향상되었다. 아울러 사람이 절단작업을 수행하다보니 안전성의 문제가 염려시 되었는 데 철단작업을 기계가 대행함으로써 작업의 안전이 보장되었다. 이와 같이 케이블 자동절단기는 경제성은 물론 안전성을 확보함으로써 케이블 철거작업의 품질개선에 큰 역할을 담당할 것이다.

• 대한수의학회지
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• 제51권2호
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• pp.93-99
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• 2011

This study surveyed the prevalence of traumatic reticular diseases (TRD) of slaughter cattle in Korea, the typology of the causative foreign bodies and the effects on beef quality and carcass weight. The overall prevalence of TRD in 3,121 slaughter cattle was 5.5%. However, the prevalence was significantly higher in Korea indigenous cattle Hanwoo (5.8%, p < 0.05) and female cattle (20.75%, p < 0.001). The prevalence significantly increased in aged cattle (p < 0.001). Major lesions related to foreign bodies were reticulitis (96%) and peritonitis (86%). Most causative foreign bodies were made of iron including nails, wires, steel rods, screw nails, and syringe needles. Cattle affected with TRD produced significantly lower grade quality of beef compared to normal cattle (p < 0.0001), but TRD did not affect carcass weight. The data will be useful in the management of TRD, with the aim of increasing beef productivity in Korea.

• 한국표면공학회지
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• 제32권3호
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• pp.428-432
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• 1999

As metallic surface has its unique lustrous appearance and optical reflectance in visible range of light, the metallization of plastic surface has been an essential drive toward weight reduction for fuel economy and decorations in transportation industry and has been put into practiced from wet chemical-electrochemial to dry vacuum process in view of an environmental effect. Electron-beam metallization was used in this work with an aim at improving the scratchproof surface hardness of plastic substrate with metallic finish character. Thin film of Al ($1000\AA$) and $SiO_2$($7000\AA$) were metallized on substrate of PC and PMMA and the films were evaluated by pencil test for surface hardness and by cross-cut tape test for adhesion. The ion beam treatment improved around twice as hard as non-treat surface. The ion beam is effect on its hardness and adhesion to surface hardened PC substrate.

• Kidney Research and Clinical Practice
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• 제36권2호
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• pp.200-204
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• 2017

Administration of autologous mesenchymal stem cells (MSCs) has been shown to improve renal function and histological findings in acute kidney injury (AKI) models. However, its effects in chronic kidney disease (CKD) are unclear, particularly in the clinical setting. Here, we report our experience with a CKD patient who was treated by intravenous infusion of autologous MSCs derived from adipose tissue in an unknown clinic outside of Korea. The renal function of the patient had been stable for several years before MSC administration. One week after the autologous MSC infusion, the preexisting renal insufficiency was rapidly aggravated without any other evidence of AKI. Hemodialysis was started 3 months after MSC administration. Renal biopsy findings at dialysis showed severe interstitial fibrosis and inflammatory cell infiltration, with a few cells expressing CD34 and CD117, 2 surface markers of stem cells. This case highlights the potential nephrotoxicity of autologous MSC therapy in CKD patients.

• 한국기계가공학회지
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• 제17권6호
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• pp.75-82
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• 2018

This study suggests an optimal design process of an LMU, which is installed on the top side of offshore structures. The LMU is consist of EB(elastomeric bearing) and steel plate, and supports the vertical loads of offshore structures and assists its stable installation. The structural design requirement of the LMU is related to its stiffness. This study utilizes the finite element analysis to predict the stiffness. The stiffness of the EB depends on the size of the bearing. Thus, the design variables in this study are defined as the thickness, the width and the number of plates. Since the LMU has different loads for different locations, its stiffness should be designed differently. The multiobjective function is introduced to attain the target stiffness. In this process, the metamodel using the kriging interpolation method is adopted to replace the true stiffness.

• International journal of advanced smart convergence
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• 제8권1호
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• pp.65-74
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• 2019

3D file formats typically include OBJ (Wavefront file format), STL (STereoLithography), and FBX (Filmbox). Each format has limitations depending on its configuration and usage, and supported formats are different depending on the software application. glTF helps uniform integration of 3D file formats and allows for more efficient transmission of large 3D geometry files by organizing them in a binary format. This paper presents explanation on OBJ, FBX, and STL which are major examples of existing 3D file formats. It also explains the concept and characteristics of glTF and compares its performance with other 3D file formats on the web. The loading time and packets of each 3D file format are measured according to the web browser environment by means of Google Chrome, Firefox and Microsoft Edge. Experimental results show that glTF is the most efficient and that it exhibits the best performance. As to STL, relatively excessive traffic was observed. This study is expected to contribute to reducing rendering time on the web as 3D file formats are used.

• 대한금속재료학회지
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• 제48권1호
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• pp.57-61
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• 2010

Nanosized surface structures of Cu powders were investigated at the atomic scale by field-emission transmission electron microscope techniques. The nanoscale surface oxide layer on the Cu powder was analyzed to be the $CU_2O$ phase by electron diffraction pattern and electron energy-loss spectroscopy. In addition, it was found from high-resolution transmission electron microscopy study that there are formed no surface oxide layers on the surface of alkanethiol coated Cu powders.

• 대한조선학회논문집
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• 제58권6호
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• pp.407-414
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• 2021

The manoeuvrability of a ship with an unwanted heel angle due to a maritime accident is changed from the original characteristics. The purpose of this study is to quantitatively investigate the change in the manoeuvring performance of a twin-screw ship under various hee angles and speed conditions. A series of free running model test campaigns were performed in the Ocean Engineering Basin of Korea Research Institute of Ships & Ocean Engineering (KRISO) for a twin-screw car ferry vessel. Turning circle test and zig-zag 10/10 and 20/20 tests were carried out on the heel angles of 0, -10, and -19.5 degrees. In addition, two-speed conditions were considered to understand the effect of ship speed. In order to examine the effect of the bilge keel, a heel angle of -22 degree where the bilge keel is exposed outside the water surface, was considered. Finally, the change of manoeuvring characteristics according to the heel angle for a twin-screw and a single-screw vessel is discussed.