• 한국정밀공학회지
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• 제32권9호
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• pp.799-805
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• 2015

The further development of information, communication and digital media technologies requires the use of advanced, miniaturized semiconductor chips that operate at a high frequency. Die bonding and wire bonding methods for semiconductor packaging have been replaced by direct attachment to the substrate after forming a bump on the chip. However, the height of the bump or ball is an important factor for defects during assembly. This paper proposes an algorithm to measure the height of the bumps or balls in semiconductor packaging with greater accuracy. The performance of the proposed algorithm is experimentally validated. Non-contact 3D measurements of a shiny round ball is quite difficult, and it is not easy to obtain accurate data. This paper thus proposes an optical method and technique to improve the measurement accuracy.

• 대한조선학회논문집
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• 제45권1호
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• pp.18-28
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• 2008

Fins are widely used for roll stabilization of passenger ferries and high performance naval ships, among others. In the present study, numerical simulations are performed to investigate the influence of end-plates upon the cavitation characteristics of a stabilizer fin for various angles of attack and speeds and the results are verified through a series of model experiments. It is found that a considerable retardation in tip vortex cavitation can be achieved with attachment of end-plates at the tip of the stabilizer fin. The results can be utilized for the design of stabilizer fins as well as the development of high performance control devices for ships.

• Nuclear Engineering and Technology
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• 제29권4호
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• pp.310-319
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• 1997

A finite element analysis of a trunnion pipe anchor is presented. The structure is analyzed for the case of internal pressure and moment loadings. The stress results are categorized into the average (membrane) stress, the linearly varying (bending) stress and the peak stress through the thickness. The resulting stresses are interpreted per Section III of the ASME Boiler and Pressure Vessel Code from which the Primary(B$_1$), Secondary(C$_1$) and Peak(K$_1$) stress indices for pressure, the Primary (B$_2$), Secondary(C$_2$) and Peak(K$_2$) stress indices for moment are developed. Based on the comparison between stress value by stress indices derived in this paper and stress value represented by the ASME Code Case N-391-1, the empirical equations for stress indices are effectively used in the piping stress analysis. Therefore, the use of empirical equations can simplify the procedure of evaluating the local stress in the piping design stage.

• 한국소음진동공학회논문집
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• 제15권7호
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• pp.843-850
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• 2005

In this study, simplified whirl flutter analyses using quasisteady aerodynamic theory have been Performed for a 2-DOF tiIt-rotor system with both pitch and Yaw motions of a rotor-nacelle. The present dynamic system consists of the rotor (propeller) , forming the gyroscopic and aerodynamic element, supported horizontally by a pylon that is pivoted at some wing attachment point. Several design parameters for rotor-nacelle system are considered to practically investigate the effects of whirl flutter stability.

• International journal of advanced smart convergence
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• 제9권2호
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• pp.123-128
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• 2020

We constructed a cooling system for solar cells using convection phenomena and investigated its cooling performance. The cooling system didn't need any driving power or water resources. The convection cooler manufactured with a right-triangle shape of an air duct was attached to the rear of the solar cell to confirm that cooling was performed using convection phenomena. When the ratio of duct width to attachment surface width was 3:7, and the ratio of entrance height and exit height of duct was 5:1, it showed the best cooling performance. Comparative experiments with solar cells without convection cooler showed that cooling effects from 16.5℃ to 20.9℃ occurred after 40 minutes exposed to the 1300W Xenon lamp condition.

• 한국정보교육학회:학술대회논문집
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• 한국정보교육학회 2004년도 동계학술대회
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• pp.207-216
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• 2004

지도 학습은 7차 교육과정의 초등학교 3학년 1학기 사회 교과서 1단원, 우리 고장의 모습에서 그림지도를 중심으로 전체 차시인 19차시에 걸쳐 다루고 있다. 그리고 4학년 1학기 사회 교과서 1단원, 우리 시 도의 모습에서도 지도의 기본 요소인 방위, 기호, 축척, 등고선을 중심으로 17차시 중 7차시에 걸쳐 학습하게 되어 있다. 그러나 자료 제작의 어려움, 개인 수준 차이로 인하여 제대로 지도 학습을 하기는 어렵다. 이에 따라 본 연구는 초등학생 지도 학습을 위한 상호작용적 WBI를 설계하고 구현하였다. 교육과정의 내용을 재구성하여 준비, 방위, 기호, 축척, 등고선, 지도 그리기의 6개 영역 아래 기본학습과 심화학습을 하게 되며, 심화학습은 학습자가 적극적으로 참여하여 학습할 수 있게 하였다. 그리고 심화학습을 마치면 보물찾기 활동이 이루어지면서 학습의 재미를 느끼도록 하였다. 이 외에도 우리들의 이야기, 토의하기 둥 다양한 상호작용 기능을 제공하여 학습의 이해를 돕는 WBI를 구현하였다.

• 한국정밀공학회지
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• 제20권2호
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• pp.120-128
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• 2003

When considering the use of rapid prototyping (RP), there are many issues a designer has to address for handling an STL model, the de facto standard fur RP. Today designers can skip all these issues by visiting web-based service bureaus that readily supply needed information for the RP services. Since orders are taken for RP parts through the web page of service providers designers are now asked to upload their STL files to the company server either by direct upload, ftp file transfer, or as an e-mail attachment. If the service bureau, however, fixes or edits an STL filceto optimize the RP process but neglects to tell its customer about the rework in detail, it may cause problems down the line in processing of the original CAD data for other applications. In this paper, we propose a framework for a collaborative virtual environment between CAD designers and RP processes on the internet which directly provides designers with an advanced preprocessor functionality, design visualization, as well as model display, repair, and slicing over the network. This can help smooth data transfer from CAD to RP process with minimum inconsistency in CAD.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.303-304
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• 2006

In this work, we developed an equipment for automatic quality control of fuel pump motor using vibration analysis. The equipment automatically performs a series of tasks such as aligning and conveying the motor, attachment/detachment of an accelerometer, data acquisition, vibration analysis, and classification, etc. Compared to previous manual operations, the developed system is able to provide considerable savings in both time and cost.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.223-224
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• 2016

Recent local advantages to improve the aesthetics of building materials connected with one of the trend of Exposed Concrete and Construction Method in various facilities and to diversify Showing a tendency to both application and development. This exposed concrete form of the features and materials is, the impact of large commercial viability and can consider I can apply to the surface of construction on a surface The diversification of the material was soon exposed directly linked to the varying aesthetics of concrete, and currently take advantage of the form of material is based on such important factor in our country Based on the concept of Exposed Concrete utilized by some construction site, design and be considered is very important elements of the put to practical use.

• 대한가정학회지
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• 제39권12호
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• pp.141-158
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• 2001

The purpose of this study was identifying the essential concept of home of middle class and aged housewives by using a critical incident methodology. All 30 subjects participated in structured interviews designed to elicit statements describing the attributes of home and non-home environment. The qualities of comfort, place-attachment, self-expression, fundamental values and personal identity, social relationships, economic value, and a suitable physical structure were associated with home environments, and were absent in residences which were not regarded as homes.