• Title/Summary/Keyword: Pin-by-pin

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Thermal Shock Cycles Optimization of Sn-3.0 Ag-0.5 Cu/OSP Solder Joint with Bonding Strength Variation for Electronic Components (Sn-3.0 Ag-0.5 Cu/OSP 무연솔더 접합계면의 접합강도 변화에 따른 전자부품 열충격 싸이클 최적화)

  • Hong, Won-Sik;Kim, Whee-Sung;Song, Byeong-Suk;Kim, Kwang-Bae
    • Korean Journal of Materials Research
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    • v.17 no.3
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    • pp.152-159
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    • 2007
  • When the electronics are tested with thermal shock for Pb-free solder joint reliability, there are temperature conditions with use environment but number of cycles for test don't clearly exist. To obtain the long term reliability data, electronic companies have spent the cost and times. Therefore this studies show the test method and number of thermal shock cycles for evaluating the solder joint reliability of electronic components and also research bonding strength variation with formation and growth of intermetallic compounds (IMC). SMD (surface mount device) 3216 chip resistor and 44 pin QFP (quad flat package) was utilized for experiments and each components were soldered with Sn-40Pb and Sn-3.0 Ag-0.5 Cu solder on the FR-4 PCB(printed circuit board) using by reflow soldering process. To reliability evaluation, thermal shock test was conducted between $-40^{\circ}C\;and\;+125^{\circ}C$ for 2,000 cycles, 10 minute dwell time, respectively. Also we analyzed the IMCs of solder joint using by SEM and EDX. To compare with bonding strength, resistor and QFP were tested shear strength and $45^{\circ}$ lead pull strength, respectively. From these results, optimized number of cycles was proposed with variation of bonding strength under thermal shock.

Design and Fabrication of CMOS Micro Humidity Sensor System (CMOS 마이크로 습도센서 시스템의 설계 및 제작)

  • Lee, Ji-Gong;Lee, Sang-Hoon;Lee, Sung-Pil
    • Journal of the Institute of Convergence Signal Processing
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    • v.9 no.2
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    • pp.146-153
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    • 2008
  • Integrated humidity sensor system with two stages operational amplifier has been designed and fabricated by $0.8{\mu}m$ analog mixed CMOS technology. The system (28 pin and $2mm{\times}4mm$) consisted of Wheatstone-bridge type humidity sensor, resistive type humidity sensor, temperature sensors and operational amplifier for signal amplification and process in one chip. The poly-nitride etch stop process has been tried to form the sensing area as well as trench in a standard CMOS process. This modified technique did not affect the CMOS devices in their essential characteristics and gave an allowance to fabricate the system on same chip by standard process. The operational amplifier showed the stable operation so that unity gain bandwidth was more than 5.46 MHz and slew rate was more than 10 V/uS, respectively. The drain current of n-channel humidity sensitive field effect transistor (HUSFET) increased from 0.54 mA to 0.68 mA as the relative humidity increased from 10 to 70 %RH.

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Replantation of Nose Amputation by Use of Medical Leech (거머리를 이용한 코 절단의 재접합술)

  • Yim, Youngmin;Kwan, Ho;Oh, Deuk Young;Lee, Ji Yeon;Jung, Sung-No
    • Archives of Plastic Surgery
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    • v.32 no.1
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    • pp.124-130
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    • 2005
  • In the microsurgical era, replantation with microvascular anastomosis is considered as the most superior method in aspects of texture, color, shape in case of nose amputation. There are some reported cases of replantation in nose amputation historically, but most of them are composite graft cases rather than microvascular anastomosis. Only a few cases of successful nasal replantation with microvascular anastomosis have been reported due to the reason that the size of vessels is usually very small and identifying suitable vessels for anastomosis is difficult. Microanastomosis of artery and microanastomosis of vein are ideal in replantation, but identifying suitable veins is often difficult. Without venous anastomosis, resolving the venous congestion remains to be a problem. We can carry out arteriovenous shunt if we can find two arteries in amputee. However, the smaller the size of amputee is, the more difficult it is to find two arteries. Instead of arteriovenous shunt, we can try external venous drainage(frequently swab, pin-prick, stab incision, IV or local heparin injection, dropping, apply of heparin-soaked gauze, use of medical leech). Here, we present three cases of replantation with microscopical arterial anastomosis (one angular artery, two dorsal nasal arteries) and external venous drainage (stab incision, application of medical leech and heparin-soaked gauze) even though the size of amputee may be as small as $1.5{\times}1.0cm$. In all cases, surgical outcomes were excellent in cosmetic and functional aspects. This report describes successful replantation by microvasular anastomosis in case that suitable veins are not found.

Contact Surface Fatigue Life for RPG System (RPG 시스템의 접촉 피로수명)

  • Nam, Hyoung-Chul;Kwon, Soon-Man;Shin, Joong-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.11
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    • pp.1453-1459
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    • 2011
  • A roller pinion gear (RPG) system composed of either a pin or a roller and its conjugated cam gear can improve the gear endurance from that of a conventional gear system by reducing the sliding contact while increasing the rolling motion. In this paper, we first proposed the exact cam gear profile and the self-intersection condition obtained when the profile shift coefficient is introduced. Then, we investigated the Hertzian contact stresses and the load stress factors while the varying the shape design parameters to predict the gear surface fatigue life, which is strongly related to the gear noise and vibration at the contact patch. The results show that the pitting life can be extended significantly by increasing the profile shift coefficient.

Development of Walking Type Chinese Cabbage Transplanter (보행형 배추정식기 개발)

  • Park S. H.;Kim J. Y.;Choi D. K.;Kim C. K.;Kwak T. Y.;Cho S. C.
    • Journal of Biosystems Engineering
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    • v.30 no.2 s.109
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    • pp.81-88
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    • 2005
  • Manual transplanting Chinese cabbage needs 184 hours per ha in Korea. Mechanization of Chinese cabbage transplanting operation has been highly required because it needs highly intensive labor during peak season. This study was conducted to developed walking-type Chinese cabbage transplanter. In order to find out design factor of the transplanter, a kinematic analysis software, RecurDyn, was used. The prototype was tested in the circular soil bin and its operating motion was captured and analyzed using high speed camera system. Prototype was one row type which utilized original parts of engine, transmission and etc. from walking-type rice transplanter in order to save the manufacturing cost. Success ratio of pick-up device of hole-pin type and latch type were $96.0\%$ and $99.2\%$, respectively. which was highly affected by feeding accuracy of feeding device of seedling. Transplanting device of the prototype produced a elliptic loci which were coincident with those produced by the computer simulation. Prototype proved good performance in transplanting with mulching and without mulching operation, either. Working performance of prototype was 22 hours per ha and operation cost of the prototype was 961,757 won per ha. So, it would reduce $88\%$ of the labor and $29\%$ of operation cost.

Retrogasserian glycerol Injection as a Treatment of Tic Doulouruex -Report of twelve cases- (삼차 신경절 액조내 글리세롤 주입에 의한 삼차신경통 치험(12예 보고))

  • Park, Wook;Hwang, Kyung-Ho;Kim, Yong-Ik;Kim, Il-Ho;Song, Hoo-Bin;Kim, Sung-Yell
    • The Korean Journal of Pain
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    • v.1 no.2
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    • pp.154-163
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    • 1988
  • In 1983, Sten H$\ddot{a}$kanson first reported the clinical safety and efficacy of retrogasserian glycerol injection as a treatment of typical trigeminal neuralgia in 96 of 100 patients during a follow-up period of 1~6 years. Since September 1987, we have injected sterile pure glycerol into the trigeminal cistern using an anterior percutaneous approach via the foramen ovale (H$\ddot{a}$rtel route) for treatment of tic douloureux in 12 patients who were suffering from attacks pain of following discontinuation of carbamazepine. The results were as follows; 1) Eight patients were completely free from pain attacks with a single dose of glycerol (0.4 ml). The remaining four patients needed a second dose (0.4 ml) several days later following the single dose. The degree of patient's subjective satisfaction by those injections was very good in 11 and fair in one. 2) During the follow-up period (1~13 months), persistent sensory deficit as determined by the pin prick test, appeared to be mild in 10 and moderate in one patient. There was no sensory deficit in one patient. further attacks of pain from those injections were still noted. 3) As a transient complication, there was headache in all patient, facial hematoma in 4, nausea and vomiting in two each, and vertigo and herpes simplex in one each. In conclusion, we confirmed that the above glycerol injections into the trigeminal cistern were clinically very effective as a treatment of tic douloureux even though the follow-up period was short.

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Varietal Difference in Root Distribution of Direct Seeded Rice

  • Kim, Hyun-Ho
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.43 no.1
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    • pp.38-43
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    • 1998
  • This study examined root growth and distribution under the direct seeding of rice cultivars developed in Korea, Japan, and the U.S. Cultivars from the U.S., especially 'M202' and 'Caloro', had a high ratio of the dry matter partitioning for root and top plant components. Caloro had high root and top growth. 'Koshihikari' from Japan showed the lowest ratio of R/T (root/total dry matter) due to the small amount of root and top plant growth. Most Japanese cultivars except transplanted 'Hatsuboshi' showed low ratio of R/T. Patterns of root distribution for each soil block were recorded by the root box-pin board method. Roots of all cultivars were distributed in blocks A, C, and E in the middle of box, i.e., just below the plant base. Roots of 'Dongjin', M202, and Caloro were distributed deeper than the others. Roots of transplanted Hatsuboshi developed much better than direct seeded Hatsuboshi. Total root weight density was highest in Caloro followed by Dongjin, 'Gancheok', 'Calrose', and the others. The root density of Caloro was twice as much as those of the others except Dongjin. According to cumulative percentages of root distribution on each soil layer, roots of most cultivars were distributed below 20cm. The U.S. cultivars showed vertically well developed root systems as compared to others. A large amount of roots were distributed in the top 15cm of soil layer for Hatsuboshi and Koshinikari, and their root systems appeared to be shallow. In contrast, the rates of root distribution in the top 10cm of soil layer were low for Dongjin, Calrose, and Caloro. These cultivars had relatively deep root systems.

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Philosophical and Theoretical Perspectives of Five Laws of Libraries and its Influence on the Library Profession: Issues and Challenges

  • Krishnamurthy, M.
    • Journal of the Korean Society for Library and Information Science
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    • v.45 no.4
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    • pp.271-286
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    • 2011
  • The role of information in knowledge society has changed. Library refers to information centre, which is actively involved information collection and promoting use of for the development of individual and society. Modern libraries are the centres of interaction for all interested in accessing information and in participating in the marathon of the present competitive age. Information and a conducive environment of its free flow is a vital tool in all forms of human endeavour. It is the link pin of national development. For a nation to develop it needs to have and provide relevant, updated and adequate information on food security, health, democracy, population, education, family planning, youth empowerment, gender quality, environment etc. The information intermediaries are the persons to modulate these complexities and find match between the information sources and users needs to satisfaction of Ranganathan's law: Books are for use; Every reader his/her book; Every book its reader; Save the time of the reader; Library is a growing organism. The relative importance of these norms in modern context has been evident from experience, study, observations, discussions, etc., and only by scientists and technologists, but also by managers, planners, and policy makers. They recognize the usefulness of information in the performance of their needs information needs. Libraries are therefore proper management, provision and dissemination of such information. It is clearly visible in the contemporary context, that the libraries in the knowledge society are much more than the book depositories This article looks at the theory/practice divide in library and information science and particularly Ranganathan's contributions, basic statements remain as valid in substance if not in expression as -to-day as when they were promulgated, concisely representing the ideal service and organizational philosophy of libraries today.

Production of Bioactive Components and Anti-Oxidative Activity of Soybean Grit Fermented with Bacillus subtilis HA according to Fermentation Time (Bacillus subtilis HA를 이용한 soybean grit의 고체발효 기간에 따른 생리활성물질 생산 및 항산화 효과)

  • Kim, Ji-Eun;Lee, Sam-Pin
    • Korean Journal of Food Science and Technology
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    • v.41 no.2
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    • pp.179-185
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    • 2009
  • Soybean grits, fortified with various bioactive components, were produced by solid-state fermentation using Bacillus subtilis HA. ${\alpha}$-Amylase activity gradually increased during fermentation over 5 days. Fibrinolytic and protease activities were highest in the soybean grits fermented for 7 days. The grits fermented for 5 days also showed the highest tyrosine content, indicating a higher peptide content. Peptides of low molecular weight (below 3,000 daltons) and browning pigments increased with increasing fermentation time. The fermented soybean grits showed higher contents of total phenolic compounds, to approximately 18 mg/g. DPPH free radical scavenging effects were higher in the soybean grits fermented for 3 days. Also, ABTS radical scavenging effects were greater in the fermented grits compared to the unfermented grits. Overall, the soybean grits fermented by solid-state fermentation for 5 days showed enhanced production of bioactive compounds and greater antioxidant properties.

A Study on the Effects of Concave Shaping in Improving Contract Pressure for Planar Array Connector Terminal Pins (평면배열 커넥터 터미널 핀에 오목형상 부여가 접압력 향상에 미치는 영향에 관한 연구)

  • Jeon, Yong-Jun;Shin, Kwang-Ho;Heo, Young-Moo
    • Design & Manufacturing
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    • v.10 no.1
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    • pp.36-40
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    • 2016
  • Connectors transmit electric signals to different parts in compact mobile display products. As products that apply this have become lightweight and smaller in size, there are growing demands for smaller and more integrated connectors, which are internal parts of the products. As a measure to address these demands, there is the planar array connector that minimizes the part by arranging the single-direction BTB connectors to two directions. As connectors become smaller in size and more highly integrated, maintaining intensity to prevent defects during impact and maintaining adhesive force to smoothly transmit electric signals are growing in importance. Thus, in order to identify the impact of concave shaping on improving adhesive power in connector terminal pins as a method to increase the connecting power of planar array connector terminal pins, this study predicted and examined the concave shaping method, number of concave shapes, and the adhesive power according to the size of the concave shape through CAE. For concave shaping, the model that added concave shaping towards the lower part of the connector terminal pin and added spokes for the area pressed down by the concave shaping was 0.74 N, showing increased adhesive force compared to existing models. Furthermore, when applying two concave shaping, rather than just one, there was a tendency for adhesive force to increase. In the case of adhesive power trends according to the size of the concave shaping, adhesive power increased and the width of the concave shape decreased, and the biggest adhesive force trends were shown when the concave shaping depth was 0.01mm.