• Transactions of Materials Processing
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• v.33 no.1
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• pp.5-11
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• 2024

The development of a next-generation hydrogen compressor, a key component in the expansion of hydrogen charging infrastructure, is in progress. In order to improve compression efficiency and durability, it is important to optimize the precision forming and shearing processes of the diaphragm, which is the bellows unit cell, as well as the optimization of diaphragm shape itself. In this study, we aim to show that die and process design technology that can synchronize the inner and outer shearing points of the diaphragm for the precision forming of product can be constructed based on a numerical simulation. First, the damage model that can predict the fracture points will be determined using the shear load and shear zone measurements obtained by performing a blanking test of AISI-633 stainless steel. Next, we will explain the overall procedure based on numerical analysis model how to determine the shearing points according to the deformation pattern of urethane die for various shearing die design.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.317-326
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• 2016

In this paper, a logic eFuse (electrical Fuse) OTP (One-Time Programmable) memory IP (Intellectual Property) using only logic transistors to reduce the development cost and period of OTP memory IPs is designed. To secure the reliability of other IPs than the OTP memory IP, a higher voltage of 2,4V than VDD (=1.5V) is supplied to only eFuse links of eFuse OTP memory cells directly through an external pad FSOURCE coming from test equipment in testing wafers. Also, an eFuse OTP memory cell of which power is supplied through FSOURCE and hence the program power is increased in a two-dimensional memory array of 128 rows by 8 columns being also able to make the decoding logic implemented in small area. The layout size of the designed 1kb eFuse OTP memory IP with the Dongbu HiTek's 110nm CIS process is $295.595{\mu}m{\times}455.873{\mu}m$ ($=0.134mm^2$).

• Journal of Bio-Environment Control
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• v.9 no.4
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• pp.201-206
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• 2000

A certain system to overcome high temperature should be introduced for the stable year-round cultivation in greenhouses. There are efficient methods to overcome high temperature such as ventilation system with shading screen, fan and pad system with screen, and fog system with screen. This study was carried out to find a means to determine the capacity of such system. Heat balance equations for each system were established and verified by experimental results. The calculated ventilation rates from heat balance equations showed a good agreement with the measured ones. The evapotranspiration coefficient was the most important parameter affecting the ventilation requirement among input parameter affecting the ventilation requirement among input parameters except weather data. When the evaportanspiration coefficient increased 1%, the ventilation requirement decreased 1.3%. Therefore the data of evapotranspiration coefficient should be accumulated by various experiments, and then design standards and selection guidelines should be provided. The simulation results for same design conditions shown that air exchanges requirement and evaporating water of fan and pad system were 5.1∼7.7% and 6.8∼9.3% larger than those of fog system, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.361-361
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• 2013

비냉각 적외선 검출소자는 빛이 전혀 없는 환경에서도 사물을 감지하는 열상장비의 핵심소자이다. 마이크로볼로미터 적외선 검출기는 상온에서 동작하며, 온도안정화를 위해 TEC를 장착하여 진공패키지로 조립된다. 패키지는 진공을 유지할 수 있도록 일반적으로 메탈로 제작되며, 단가 감소 및 생산성 증대를 위해 wafer level packaging 방법을 이용한다. 마이크로볼로미터의 특성은 패키지의 진공 변화에 매우 민감하다. 센서의 감도를 증가시키기 위해서는 진공환경을 유지해야 한다. 볼로미터 소자의 특성은 상압에서 열전도는 기판과 멤브레인 사이의 에어갭을 통해 열손실을 야기하므로 센서의 반응도가 현저히 줄어든다. 에어갭이 1 um 정도 되더라도 그 사이에 존재하는 열전도가 가능하므로 진공을 유지하여 열고립 상태를 증대시킬 수 있다. 이에 본 연구에서는 소자의 동작시 압력, 즉 진공도가 볼로미터 소자의 반응도 특성에 미치는 영향을 조사하였다. 마이크로볼로미터 소자는 $2{\times}8$ 어레이 형태로 제작하였으며, metal pad를 각 단위셀에 배치하였으며, 공통전극으로 한 개의 metal pad를 넣어 설계하였다. 흡수체로써 VOx를 사용하였으며, 열 고립구조를 위해 2.5 um 공명 흡수층의 floating 구조로 멤브레인을 형성하였다. 진공패키지는 메탈패키지를 제작하여 볼로미터 칩을 TEC 위에 장착하였으며, 신호의 감지를 위해 가변저항을 매칭시켰다. 반응도는 신호 대 잡음 값을 획득하여 소자에 도달하는 적외선 에너지에 대해 반응하는 값을 계산에 의해 얻어내는 것이다. 픽셀 크기는 $50{\times}50$ um이며, 패키지 조립 공정 후 온도변화에 따른 저항 측정을 통해 TCR 값을 얻었다. 이때 TCR은 약 -2.5%/K으로 나타났다. $2{\times}8$의 4개 단위소자에 대해 측정한 값은 균일하게 TCR 값이 나타났다. 광반응 특성은 볼로미터 단위소자에 대해서 먼저 고진공(5e-6 torr) 하에서 측정하였으며, 반응도는 25,000 V/W의 값을 나타내었고, 탐지도는 약 2e+8 $cmHz_{1/2}$/W로 나타났다. 패키지의 압력 조절을 위해 TMP 및 로터리 펌프를 이용하여 100 torr에서 1e-4 torr의 범위에서 압력조절 밸브를 이용하여 질소가스의 압력으로 진공도를 변화시켰다. 적외선 반응신호는 압력이 증가함에 따라 감소하였으며, 2e-1 torr의 압력에서 신호의 크기가 감소하기 시작하여 5 torr에서 반응도의 1/2 값을 나타냄을 알 수 있었다. 30 torr 이상에서는 신호가 잡음값 과거의 동일하여 신호대 잡음비가 1로 나타남을 알 수 있었다. 또한 진공도 변화에 대해, 흑체온도에 따른 반응도 및 탐지도의 특성을 조사한 결과를 발표한다. 반응도의 증가를 위해 진공도는 진공도는 1e-2 torr 이하의 압력을 유지해야 함을 본 실험을 통해 알 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1185-1192
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• 2003

Governing parameters for determination of the location of crack initiation and direction of crack initiation were investigated by performing fretting fatigue tests and analysis on Al 2024-T351. Fatigue tests were carried out using biaxial fatigue machine. It was shown that the dominant fatigue crack tended to initiate at the outer edge of one of the four bridge pads, growing at an angle beneath a pad, before turning perpendicular to the orientation of the axial load. Distribution of stresses generated during fretting fatigue loading along the interface was calculated by elastic FE simulation. It can be known that the location of crack initiation can be predicted by using the maximum tangential stress range. Futhermore, the crack initiation direction can also be predicted by a maximum tangential stress range.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.171-172
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• 2013

기존의 종이책은 다양한 스마트 모바일기기의 활발한 보급으로 인해 전용 단말기와 뷰어 앱(Veiwer App)을 통해 전자책(e-book)으로 서비스되고 있다. 최근에는 텍스트(Text) 중심의 전자책과 달리, 텍스트와 함께 동영상, 다양한 상호작용 요소를 중심으로 하는 앱북(App book)의 형태로 진화되고 있다. 아이패드(iPad)용 앱스토어(App Store)에서는 도서 관련 앱이 28%를 차지할 정도로 앱북 시장이 빠르게 성장함에도 불구하고, 여러 가지 전자책 전용 단말기, 뷰어 앱 UI(User Interface) 관련 연구들에 비해 앱북의 콘텐츠 및 UI에 대한 연구가 상대적으로 부족한 상황이다. 이에, 본 논문에서는 앱북 콘텐츠의 표시 방법에 따라 3개의 유형으로 분류하고, 대표 앱북을 선정하여, 콘텐츠의 객체 표시방법에 대해 분석하고, 상호작용 요소들을 분석하였다. 이를 통해, 객체 별 상호작용 요소를 고려한 전자잡지형 앱북의 콘텐츠 표시 방법 프레임워크를 설계하였다.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.28-31
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• 2007

자동차 측면충돌시 인체의 상해를 줄이기 위하여 도어 시스템 부품 중에 도어트림이 충격을 차단하고 인체를 보호하는 역할을 하고 있다. 차체 판넬이 변형되어 도어트림에 전달되는 충돌 에너지를 패드가 흡수 하는데 중대한 기능을 한다. 이전에 충격흡수 패드는 외곽부위의 수평면에 의존하여 설계되었으며 이 구조는 점진적으로 충격을 흡수 하는데 문제점이 발견 되었는데 트리즈의 6단계 창의성 기법을 적용하여 패드의 주요 특성을 찾아내고 그 특성에 모순을 해결하여 차종에 적용할 수 있는 기본 단면과 설계 자유도가 높은 충격흡수부재를 개발 하였다.

• Textile Coloration and Finishing
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• v.10 no.3
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• pp.50-56
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• 1998

Nonwoven fabric was treated with chitosan solution to impart antimicrobial activities by pad-dry method. Antimicrobial activity was measured by Shake Flask Method. Two chitosans of different molecular weight(Mw) with similar degree of deacetylation(DDA) were used : ca. 1,800(chitosan oligomer : DDA 84%) and 180,000(DDA 86%). Chitosan oligomer displayed high antimicrobial activity against P. vulgaris at 0.01%, S. aureus and E. coli at 0.05% treatment concentration, shelving above 90% of reduction rate. Chitosan of Mw 180,000 was effective against S. aureus, E. coil and P. vulgaris at 0.05% treatment concentration, showing almost 100% reduction rate. While chitosan of Mw 180,000 shelved reduction rate above 75% against K. pneumoniae and P. aeruginosa at 0.5% treatment concentration, chitosan oligomer was not effective against them. Fabrics become stiffer and less air permeable as treatment concentration increases. Liquid strike-through time of the sample treated with 0.5% chitosan oligomer solution (3.0 sec) was comparable with a hydrophilic finished sample commercially available(2.6 sec).

• Journal of Oral Medicine and Pain
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• v.13 no.1
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• pp.61-69
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• 1988

The study of the muscle fiver composition and the muscle fiver type conversion during unilateral edentulous condition was undertaken in the rostral superficial masseter muscle of the whiter rat. 16 4-week-old male white rats weighting approximately 130gm that crowns of left upper and lower molare were cut intentionally, were divided into 4 groups (one control group and 3 experimental groups). After experimental groups were sacrificed by etherization in 6 days($E_1$), 18 days($E_2$) and 36 days($E_3$) separately, samples of the rostral superficial masseter muscle were obtained bilaterally and the proportion of type I, type IIA, type IIB, and type IIC fibers was determined and counted according to their histochemical activity of myosin ATPase (at pH 9.4, pH 4.6, and pH 4.2)and PAD staining. The obtained results were as follows : 1. The rostral superficial masseter muscle of the white rat contained approximately 47.5% type I fiber and 52.5% type II fiber. 2. Type I/ Type II ratio of molar-present side was increased significantly in the group E2 (18 days group) 3. Type IIA fiber was increased at molar-present side and decreased at molar-absent side in experimental groups.

• Journal of the Korean Society for information Management
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• v.28 no.3
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• pp.313-333
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• 2011

Many e-book readers have become available as e-books are in popular use these days. We first developed the evaluation criteria and elements for testing the usability of e-book readers and then examined the usability of three e-book readers. The usability testing was conducted using three e-book readers that were most popular with 15 participants that consisted of middle school students, university students, and office workers. The study found that iPad showed the best usability. In case of Amazon Kindle, participants indicated that the lack of the touch function imposed a great deal of negative impact on the usability of the interface. Also, the hardware- and software-oriented usability provided by an e-book reader was considered to be a very important element for the users, and the portability in connection with the hardware-oriented aspect of an e-book reader was shown to be of great effect to the overall usability of an e-book reader.