• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.32-35
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• 2002

The work focuses on the development of a Cu lead-frame with a single-sided adhesive tape for cost reduction and reliability improvement of LOC (lead on chip) package products, which are widely used for the plastic-encapsulation of memory chips. Most of memory chips are assembled by the LOC packaging process where the top surface of the chip is directly attached to the area of the lead-frame with a double-sided adhesive tape. However, since the lower adhesive layer of the double-sided adhesive tape reveals the disparity in the coefficient of thermal expansion from the silicon chip by more than 20 times, it often causes thermal displacement-induced damage of the IC pattern on the active chip surface during the reliability test. So, in order to solve these problems, in the resent work, the double-sided adhesive tape is replaced by a single-sided adhesive tape. The single-sided adhesive tape does net include the lower adhesive layer but instead, uses adhesive materials, which are filled in clear holes of the base film, just for the attachment of the lead-frame to the top surface of the memory chip. Since thermal expansion of the adhesive materials can be accommodated by the base film, memory product packaged using the lead-flame with the single-sided adhesive tape is shown to have much improved reliability. Author allied this invention to the Korea Patent Office for a patent (4-2000-00097-9).

• 전기학회논문지
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• 제56권12호
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• pp.2217-2220
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• 2007

In this paper, we propose a new wafer level package (WLP) for the RF MEMS applications. The Film Bulk Acoustic Resonator (FBAR) are fabricated and hermetically packaged in a new wafer level packaging process. With the use of Au-Sn eutectic bonding method, we bonded glass cap and FBAR device wafer which has groove-shaped via formed in the backside. The device wafer includes a electrical bonding pad and groove-shaped via for connecting to the external bonding pad on the device wafer backside and a peripheral pad placed around the perimeter of the device for bonding the glass wafer and device wafer. The glass cap prevents the device from being exposed and ensures excellent mechanical and environmental protection. The frequency characteristics show that the change of bandwidth and frequency shift before and after bonding is less than 0.5 MHz. Two packaged devices, Tx and Rx filters, are attached to a printed circuit board, wire bonded, and encapsulated in plastic to form the duplexer. We have designed and built a low-cost, high performance, duplexer based on the FBARs and presented the results of performance and reliability test.

• 한국전기전자재료학회논문지
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• 제11권5호
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• pp.353-357
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• 1998

Cracking problem of Epoxy Molding Compound(EMC) is critical for the reliability of the plastic package during temperature cycling and IR-reflow condition. Fracture toughness of EMC, which is defined as the resistance of EMC to the crack propagation, is a useful factor in ht estimation of EMC against package crack. Thus, development of EMC having high fracture toughness at a given loading condition would be important for confirming the integrity of package. In this study, toughness of several EMC was measured by varying the test conditions such as temperature, loading speeds, and weight percent of filler in order to quantify the variation of toughness of EMC under various applicable conditions. It was found from the experiments that toughness of all EMC has following trends, i.e., it rapidly decreases over the glass transition temperature, remains almost same or little decreases below $0^{\circ}C$. It decreases with the growth of cross head speed in EMC and the weight percent of filler as the degree of brittleness of EMC increases with the amount of filler content.

• Archives of Plastic Surgery
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• 제51권2호
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• pp.251-257
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• 2024

Background Plastic surgery has developed to benefit in a variety of challenging areas formerly handled by other disciplines. Medical students do not have a clear picture of plastic surgery as a career due to lacking scope, clinical practice, and understanding of plastic surgery as a clinical area of expertise, including general practitioners, nursing staff, medical trainees, and the general public, and misconceptions about the extent of reconstructive and plastic surgery. Methods A cross-sectional observational study was conducted on Kuwait University Medical students (2nd-7th Years) over a period of 1 month. A questionnaire and a consent form were provided to eligible students. The inclusion criteria were Kuwait University Medical students from 2nd to 7th Years with signed consent form. The response was collected via email sent in coordination with the Vice Dean of Student Affairs in the Faculty of Medicine. Using statistical package for the social sciences, responses were statistically analyzed. Pearson's chi-square test was used to calculate p-values, where p < 0.05 was considered statistically significant. Results A total of 244 eligible medical students, 121 males and 123 females, were included in the study, with a mean age of 21 (±2) years. Similarly, 126 (51.6%) were preclinical students (2nd-4th-year students), while 118 (48.4%) were clinical students (5th-7th-year students). About 79.8% of medical students believed that plastic surgery plays an essential role in trauma management, whereas 9.2% did not consider plastic surgery significant for trauma management. This study found that only 15.5% of medical students were interested in enrolling in plastic surgery residency after graduation, while 47.1% of students did not consider plastic surgery residency after graduation. However, 37.4% were uncertain. The two most driving factors in deciding on plastic surgery residency were expected income (61.8%) and lifestyle (14.3%). Conclusion Improving medical students' education quality can enhance their perception and awareness of plastic surgery. Students should be taught the broader scope of plastic surgery. The inclusion of formal training during undergraduation is the essence of time and should be added to or improved during plastic surgery rotations with more emphasis on reconstructive and hand/peripheral nerve surgery. Student-led interest groups can be a useful tool for educating students about their specialty.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1998년도 추계학술대회논문집:21세기에 대비한 지능형 통합항만관리
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• pp.223-238
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• 1998

In this study, to investigate the effect of process variables such as reduction in area, semi-die angle and the rectangular ratio to the corner filling which influences the dimensional accuracy of the final product in the drawing of the cluadrangle rod from a round bar, it has been simulated by three dimensional rigid-plastic finite element method. In order to reduce the number of simulation artificial neural network has been introduced. Also, through the experimental investigation, the present results have been implemented on the industrial product. In results, the main process variable is the combination of the semi-die angle in case of the irregular shaped drawing process and reduction in area in the event of regular shaped drawing process, respectively.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.73-76
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• 2002

In this paper we present an integrated Hail sensor It for fan motors, fabricated in industrial bipolar process. As a discrete Hall sensor and signal processing circuitry In the fan motor system were Integrated into single chip a temperature dependence of Hall sensitivity and Hall offset voltage can be compensated and cancelled by on-chip circuitry. We Propose a novel temperature compensation of Hall sensitivity with negative temperature coefficient (TC) using the differential amplifier gain with Positive TC. After a package of the chip was sealed using a plastic Package 20 Pins, the thermal and magnetic characteristics were investigated. The obtained experimental results are in agreement with analytical predictions and have more excellent performance than\ulcorner conventional the fan motor system using discrete Hall sensor.

• Journal of Welding and Joining
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• 제17권2호
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• pp.61-65
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• 1999

Because of the need for packages which accommodate high pin count, high density and high speed device, PBGA(plastic ball grid array) package gets more spotlight. But the substrate material which is used for PBGA package is in nature susceptible to moisture penetration. The objective of the study is to find out the path of delamination in the stacked structure of substrate. To increase the adhesion between the cooper laminate and PSR(photo solder resist) which is the weakest part, experiments were performed by changing parameters of printing pre-treatment and post-treatment process. As a result of experiments, the factor effects on the adhesion between the cooper laminate and PSR is caused by all of the pre-treatment and post-treatment condition. A considerable change was observed depending on the amount of UV irradiation after thermal cure which is typical of printing post-treatment condition rather than pre-treatment condition.

• 전자공학회논문지D
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• 제35D권10호
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• pp.22-28
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• 1998

플라스틱 패키지 재료가 본딩와이어의 혼신에 미치는 영향을 모멘트법 (Method of Moments)을 이용하여 주파수 영역에서 해석하고, fast Fourier transform을 적용하여 시간 영역에서의 전송 및 혼신 펄스 응답을 구하였다. 해석결과, 본딩와이어가 플라스틱 패키지 내부에 있을 때, 전송 특성은 유전효과로 인하여 개선되나 혼신은 증대된 방사효과로 인하여 크게 증가하며, 이러한 혼신 증가는 시간영역에서의 혼신 펄스 왜곡 현상을 현저하게 함을 관찰하였다. 한편, 정적 해석 방법을 이용한 플라스틱 패키지에 묻힌 본딩와이어의 해석 결과로부터, 모멘트법 결과와는 달리 방사효과에 의하여 증대되는 혼신현상을 계산하지 못하므로 본딩와이어 초고속 펄스 혼신 예측에는 적합하지 않음을 확인하였다. 또한, 본딩와이어 구조를 변화시키면서 혼신 펄스 응답을 살펴 본 결과, 방사효과에 의한 혼신의 우세함으로 인하여 본딩와이어간의 단순한 사이 간격 증가는 혼신감소에 효과적이지 않음을 관찰하였다. 본 해석 결과는 고속 디지털 IC 및 초고주파 소자의 플라스틱 패키지 설계시 유용하게 사용될 수 있으리라 기대된다.

• 한국식품영양과학회지
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• 제41권3호
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• pp.418-429
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• 2012

현재 시장에서 유통되고 있는 떡 포장은 플라스틱 재료가 주로 사용하며 랩핑 포장 방법을 많이 사용하고 있다. 현재 시장에서 판매되는 떡들은 당일 생산 및 당일 소비(2일내 소비)를 하는 제품으로 포장을 중요성을 많이 고려하고 있지 않지만, 최근 유통기한이 늘어난 떡 제품의 상품화를 위해서 떡 포장의 개발에 관심이 높아지고 있다. 떡의 상품화 증대를 위하여 수도권 지역 소비자 대상 중심으로 포장 개선에 대한 기호도 조사에서 절취선을 손으로 개봉하는 개봉방법, 2~3개의 파티션(홈)이 존재하는 내부 디자인, 제품을 낱개 포장한 포장, 포장에 직접 인쇄하는 인쇄방법, 내용물의 상태가 완전히 보일 수 있는 포장방법을 선호하는 것으로 파악되었다. 본 연구는 국내 떡 제품에 대한 상품성 부여를 위하여 현재 소비자가 떡 제품 포장의 선호하는 트랜드 분석과 포장의 중요성이 인지되고 있다는 점에서 큰 의미를 부여할 수 있다. 따라서 본 연구에서 고려한 국내 주요 떡 제품 포장에 따른 소비자 구입 선호도를 조사 연구를 기반으로 다양한 떡 종류 및 형태에 따른 포장 소비 선호도 그리고 각 포장 방법 변경에 따른 상품화 가능성 및 가격 변화 요인을 고려한 연구가 향후 필요할 것으로 판단된다. 조사 연구 결과로 제시한 떡 포장 설계 구조의 적용과 함께 떡의 품질 개선을 위한 기능성 포장재 적용 연구 및 최적 제품 환경을 조성하는 포장 기법 연구 등을 통하여 떡 제품의 부가가치를 향상 시킬 수 있으리라 기대해 본다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.65-70
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• 2001

The compression toe of structural wall is designed to resist the axial compression and shear force caused by wind or earthquake. The performance of shear wall used in tall building is highly influenced by combined shear and axial force. For this reason, it is possible to result in local brittle failure because of concentrated damage in the potential plastic hinge region under severe earthquake. Thus, it is necessary to establish the lateral confinement details at the plastic hinge of shear wall so that shear wall can behave a ductile manner, The objective of this study is to evaluate the seismic performance of L-shaped walls with different confinement details. For this purpose, three wall specimens were tested experimentally and also analyzed using Nonlinear FEM package.