• 한국전기전자재료학회논문지
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• 제15권4호
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• pp.344-348
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• 2002

As microelectronics technology continues to progress, there is also a continuous demand on highly integration and miniaturization of systems. For example, it is desirable to package several integrated circuits together in multilayer structure, such as multichip modules, to achieve higher levels of compactness and higher performance. Passive components (i.e., capacitors, resistors, and inductors) are very important fort many MCM applications. In addition, the low-temperature co-fired ceramic (LTCC) process has considerable potential for embedding passive components in a small area at a low cost. In this paper, we investigate a method of statistically modeling integrated passive devices from just a small number of test structures. A set of LTCC inductors is fabricated and their scattering parameters (s-parameters) are measured for a range of frequencies from 50MHz to 5GHz. An accurate model for each test structure is obtained by using a building block based modeling methodology and circuit parameter optimization using the HSPICE circuit simulator.

• Agricultural and Biosystems Engineering
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• 제4권1호
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• pp.34-38
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• 2003

A mathematical model was developed for estimating the mechanical interrelation between characteristics of soil and main design factors of a tracked vehicle, and predicting the tractive performance of the tracked vehicle. Based on the mathematical model, a computer simulation program (TPPMTV) was developed in the study. The model considered the continuous change in tension for the whole track of a tracked vehicle, the analysis of shape and tension of the track segment between sprocket and first roadwheel, and the side thrust on both sides of grouser by the active earth pressure theory in predicting the tractive performance of a tracked vehicle. Also, the model contained not only sinkage depth of the track but the pressure distribution under the track in analyzing the side thrust. The effectiveness of the developed model was verified by performing the draw bar pull tests with a tracked vehicle reconstructed for test in loam soil with moisture content of 18.92％. The predicted drawbar pulls by the model were well matched to the measured ones. Such results implied that the model developed in the study could estimate the drawbar pulls well at various soil conditions, and would be very useful as a simulation tool for designing a tracked vehicle and predicting its tractive performance.

• Child Health Nursing Research
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• 제24권3호
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• pp.310-318
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• 2018

Purpose: The purpose of this study was to develop a first aid coaching program (FACP) and to investigate its effects on the first aid knowledge, confidence, and performance of childcare teachers. Methods: A Delphi survey that included 16 experts was used to develop the FACP. A total of 60 participants were included to test the effectiveness of the program. The FACP developed using the survey results focused on improving first aid knowledge, confidence, and performance using a coaching-based method. First aid and cardiopulmonary resuscitation (CPR) performance was assessed using 39 items from the program content. Results: Using a 3-round Delphi survey, 6 areas and 42 detailed topics for group and individual coaching programs were developed. The knowledge scores were significantly higher in the experimental group than in the control group (t=4.24, p=.001). The confidence scores were significantly higher in the experimental group than in the control group (F=3.89, p<.001). The performance scores were significantly higher in the experimental group than in the control group (t=12.40, p<.001). Conclusion: Continuous application of the FACP among child care teachers is expected to minimize the harm caused by minor accidents at child care facilities. This program should be formally implemented on a consistent basis.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.652-659
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• 2011

Due to overuse of commercial network systems such as bluetooth and WI-FI, the problems of frequency interruption and line-crossing may arise. For this reason, wireless communication frequency ISM 2.4GHz, a recently adapted concept in Korea which is employeed by RF-CBTC system, is predicted not to have guarantee for outstanding and continuous performance. Therefore in this study, considering these problems, 5GHz capacity wireless Lans with international standard 802.11a/b/g applied were installed in the underground urban transit areas and it was proved that these lans exceeded the performance level of 2.4GHz with international standard 802.11b which is being introduced in the nation. In addition, it was verified through carrying out an application test that the communication condition was stable in a running train with high speed in the tunnel.

• Journal of Welding and Joining
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• 제32권3호
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• pp.53-59
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• 2014

The mechanical stability of solder joints in electronic devices with Sn-Ag-Cu is a continuous issue since the material was applied to the industry. Various shock test methods were developed and standardized tests are used in the industry worldwide. Although it is applied for several years, the detailed mechanism of the shock induced failure mechanism is still under investigation. In this study, the effect of external temperature was observed on large Flip-chip BGA components. The weight and size of the large package produced a high strain region near the corner of the component and thus show full fracture at around 200G level shock input. The shock performance at elevated temperature, at $100^{\circ}C$ showed degradation based on board pad designs. The failure mode and potential failure mechanisms are discussed.

• 전기전자학회논문지
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• 제4권2호
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• pp.192-201
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• 2000

이 논문은 연속형 Hopfield 신경회로망에서 뉴론의 입력단에 연결하는 컨덕턴스가 시스템의 안정도에 미치는 영향에 대해 논의 하고자 한다. 이 컨덕턴스는 뉴론의 입력단과 ground사이에 캐패시터와 병렬로 연결되어 있는 데, 시스템의 안정도에 영향을 미치는 것으로 알려져 있으나, 이 것에 대해 알려진 것이 별로 없어, 여기서 그 것에 자세히 논의 한다. 그리고 또한 이 컨덕턴스를 조절하여 시스템의 안정도와 더불어 시스템의 performance를 개선하는 방법에 대해 다룬다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.107-109
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• 2006

The purpose of this paper is to introduce the new products for replacing on the old technical cooperation products which have 24 kinds of industrial inverter model. The core algorithm for vector control and sensorless control and the operation program for LCD operator have been developed. Through the continuous test, the improvement of speed/torque control performance and the control program for special target loads will be performed.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.341-342
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• 2018

Waterproofing materials and construction methods have been developed and applied to various construction sites since the past. However, there many cases where the waterproofing performance is not satisfactory, leading to continuous water leakage. It has been observed that a key reason for this is because waterproofing method and material selection is not optimized in terms of the appropriate application area and environmental degradation factors. This paper proposes that future selection of waterproofing methods should consider the following evaluation criteria; 1) waterproof performance evaluation according to site conditions, 2) evaluation of construction method, 3) manufacturing and maintenance of waterproofing systems.

• Smart Structures and Systems
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• 제21권2호
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• pp.235-248
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• 2018

An efficient method utilizing the multi-stage improved differential evolution algorithm (MSIDEA) as an optimization solver is presented here to detect the multiple-damage of structural systems. Natural frequency changes of a structure are considered as a criterion for damage occurrence. The structural damage detection problem is first transmuted into a standard optimization problem dealing with continuous variables, and then the MSIDEA is utilized to solve the optimization problem for finding the site and severity of structural damage. In order to assess the performance of the proposed method for damage identification, an experimental study and two numerical examples with considering measurement noise are considered. All the results demonstrate the effectiveness of the proposed method for accurately determining the site and severity of multiple-damage. Also, the performance of the MSIDEA for damage detection compared to the standard differential evolution algorithm (DEA) is confirmed by test examples.

• 기술사
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• 제45권6호
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• pp.28-32
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• 2012

Namhae chemical is one of the largest fertilizer manufacturing company in Korea which company has operating 4 unit agitator gear boxes and producing variety kinds of fertilizer production. The gearbox operating temperature of agitator is approximated in $55^{\circ}C{\sim}90^{\circ}C$ and required to keep operating continuous without stopping. The system required high performance oil and longer oil drain interval as limited workforce in maintenance team. It was lubricated by mineral gear oil of ISO VG 320 and also need to change to new oil frequently. Namhae Chemical would expect to keep stable operating condition without shut down and consider, lower cost of operation and equipment protection.