• Title/Summary/Keyword: Pull-through

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A Study on the Creep Characteristics of QFP Solder Joints (QFP 솔더접합부의 크립특성에 관한 연구)

  • Cho, Yun-Sung;Cho, Myung-Gi;Kim, Jong-Min;Lee, Seong-Hyuk;Shin, Young-Eui
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.5
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    • pp.151-156
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    • 2007
  • In this paper, the creep characteristics of lead and lead-free solder joint were investigated using the QFP(Quad Flat Package) creep test. Two kind of solder pastes(Sn-3Ag-0.5Cu, Sn-0.2Sb-0.4Ag-37.4Pb) were applied to the QFP solder joints and each specimen was checked the external and internal failures(i.e., wetting failure, void, pin hole, poor-heel fillet) by digital microscope and X-ray inspection. The creep test was conducted at the temperatures of $100^{\circ}C$ and $130^{\circ}C$ under the load of 15$\sim$20% of average pull strength in solder joints. The creep characteristics of each solder joints were compared using the creep strain-time curve and creep strain rate-stress curves. Through the comparison, the Sn-3Ag-0.5Cu solder joints have higher creep resistance than that of Sn-0.3Sb-0.4Ag-37.4Pb. Also, the grain boundary sliding in the fracture surface and the necking of solder joint were observed by FE-SEM.

A Study of Local Ventilation Design on PC Programm (국소환기 설계의 전산화에 관한 연구)

  • Yoon, Myong Cho
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.3 no.2
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    • pp.213-226
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    • 1993
  • The purpose of this study is to computerize the design of single source for a duct work system which is essential for the improvement of working places. There are different types of hood, such as general hood, push pull hood and canopy hood. And out of these three types, general hood and canopy hood were used as subjects of this study. The software used here was Quattro Pro 123 programm, and the hardware was IBM PS/SX(type 5510-SK4 S/N 83-05164). And the results are tabulated in

    and
    . All of the hazardous factors of working places, except for physical factors, such as noise, vibration, illumination and etc, are control measurement related. In order words, workiong places that have problems with toxic gas, mist, fume, dust, odors, biological factors or wetness can be improved by means of the local ventilation design. However, the reqires very complicate processes, and in the case of canopy hood, particularly, one runs into difficulties due to frequent discrepancies generated from calculations through many processes. Recently, progress of the computer hardware technics has been dazzling, and also the software is development rapidly. As proven in the results of this study, it is good that designs for industrial ventilation systems are readily available for easy use. It is hopeful that young scholars will develop easier and quicker methods for local ventilation designs in the future.

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  • A Study of Gigong-Yangsaeng(Good life) and The old-Health care (기공양생(氣功養生)과 노인보건(老人保健)에 대한 고찰(考察))

    • An Hyeon-Guk;Shin Yong-Hyun;Gu Byeong-Su
      • Journal of Oriental Neuropsychiatry
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      • v.11 no.2
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      • pp.177-187
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      • 2000
    • The purpose of this thesis is to make manifest the relation of Gigong- Yangsaeng(good life) and The old-health care, and through the conclusion, to study that how much the method of Gigong-Yangsaeng con entertain with refreshments to the stop of being old. Especially this thesis managed to divide the effect of the stop of being old by Gigong-Yangsaeng 3 parts and studied, the first effect is mental that, the second effect is the increase of immunity and the third effect is that of the stop of being old by chemical reaction.The results were as follows:The purpose of the method of Gigong-Yangsaeng is to increase the strength of human body and to resist disease and live long by training and practicing ourselves'Gi(energy of power), People call the method of good life and being old like this Gigong-Yangsaeng. Gigong-Yangsaeng is a method of Yangsaeng(good life) to pull off the purpose of being healthy and strong. We can get some effects of Gigong-Yangsaeng by uniting human mind and body into one. Entirely the key of those effects depends on Jo-sin(to control human body). Jo-sik(to control breath). Jo-sim(to control human mind).

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    Design and Implementation of 30" Geometry PIG

    • Kim, Dong-Kyu;Cho, Sung-Ho;Park, Seoung-Soo;Yoo, Hui-Ryong;Park, Yong-Woo
      • Journal of Mechanical Science and Technology
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      • v.17 no.5
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      • pp.629-636
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      • 2003
    • This paper introduces the developed geometry PIG (Pipeline Inspection Gauge), one of several ILI (In-Line Inspection) tools, which provide a full picture of the pipeline from only single pass, and has compact size of the electronic device with not only low power consumption but also rapid response of sensors such as calipers, IMU and odometer. This tool is equipped with the several sensor systems. Caliper sensors measure the pipeline internal diameter, ovality and dent size and shape with high accuracy. The IMU (Inertial Measurement Unit) measures the precise trajectory of the PIG during its traverse of the pipeline. The IMU also provide three-dimensional coordination in space from measurement of inertial acceleration and angular rate. Three odometers mounted on the PIG body provide the distance moved along the line and instantaneous velocity during the PIG run. The datum measured by the sensor systems are stored in on-board solid state memory and magnetic tape devices. There is an electromagnetic transmitter at the back end of the tool, the transmitter enables the inspection operators to keep tracking the tool while it travels through the pipeline. An experiment was fulfilled in pull-rig facility and was adopted from Incheon LT (LNG Terminal) to Namdong GS (Governor Station) line, 13 km length.

    Development of Proximity Exposure System with Vertical Structure for Plasama Display Panel (PDP용 수직형 구조의 근접 노광장치 개발)

    • Park, Jeong-Gyu;Jeong, Su-Hwa;Lee, Hang-Bu
      • Transactions of the Korean Society of Mechanical Engineers A
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      • v.24 no.9 s.180
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      • pp.2371-2380
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      • 2000
    • In this paper, we developed the proximity exposure system with the vertical structure of glass and mask stage to minimize the mask's warp caused by the pull of gravity. This system, which canirradiate the ultra violet through 1440 H 850 $\textrm{mm}^2$ and 1330X 1015 $\textrm{mm}^2$ exposure area, has the followingcharacteristics. The glass stage can be inclined by 80 degrees at vertical structure to load substrate withsafety on it. When the glass stage is the vertical state, the gap control, alignment control and exposureof ultra violet are executed. So, it enhances the pattern uniformity by minimizing the mask's warp. Theglass stage can also control the gap between the mask and the substrate by the coarse and fine motioncontrol. The mask stage can adjust the posture of photomask to the position of substrate by imageprecessing method. The galss stage for the gap control and the mask stage for the alignment aredesigned independently for each function.

    Design and Fabrication of the Frequency Doubler for 24GHz Local Oscillator (24GHz 대역 국부발진기용 주파수 체배기 설계 및 제작)

    • Seo, Gon;Kim, Jang-Gu;Han, Sok-Kyun;Park, Chang-Hyun;Choi, Byung-Hai
      • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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      • 2003.10a
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      • pp.411-415
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      • 2003
    • In this paper, a reflector type frequency doubler for local oscillator at 24GHz is designed and fabricated with ne71300-N MESFET. Optimum source and load impedances are decided through a multiharmonic load pull simulation technique. A conversion gain ran be improved using the reflector and fundamental and third harmonics are well suppressed with open stub of λ/4 length. Measured results show output power at 0dBm of input power is -3.776dBm, conversion gain 0.736dB, harmonic suppression 41.064dBc, respectively.

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    Fire Risk Assessment for Subway Station According to Supply and Exhaust Conditions (지하철 승강장 급배기 조건에 따른 화재 위험성 평가)

    • Kim, Ha-Young;Rie, Dong-Ho;Kim, Jung-Yup
      • Fire Science and Engineering
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      • v.22 no.5
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      • pp.29-34
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      • 2008
    • In this research, to establish the emission for the people who are clearing out, through the numerical analysis using the CFD model, the dangerousness has been investigated in the various emission conditions in a station platform. As a result of research, it is found out that the temperature variation falls between 65.37% and 74.97% to compare without installation of platform screen doors. In the addition, with the supply mode or push-pull mode, the warm current is generated in the platform so the temperature and the layer of smoke are stirred up and felled off. It will make the dangerousness when the people escape. Therefore, when the capacity of emission and the space of platform is set up, the design regards the properties of the fire emission.

    An Experimental Study on the Lightfast of Silk Fabrics (견직물의 내광성에 관한 연구)

    • 박일록
      • Journal of the Korean Home Economics Association
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      • v.20 no.1
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      • pp.1-10
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      • 1982
    • This experiment was made on the basis of the general observation that silk fabrics is flaccid in sun light. The purpose of this test is to examine efficiency between the processed thread and the unprocessed one after putting the later under the xenon-lit system, which produces continuous spectrum of bright white beam similar to sun light. (i) Color division of silk thread : white, yellow blue (ii) light division and irradiation time : sun lightlongrightarrow210 hrs, Xenonlongrightarrow50,100, 150 hrs. Under the above conditions each object was be tested with and extensometer, TENSILON Type III for the results of (a) the weight-expansibility curve of the silk thread (b) the relationship between cutting in tensity and maximum, weight (c) maximum expansion rate (d) the expansion energy of the tested silk thread (e) the beginning pull-stretch resistance rate of the tested silk thread (f) color difference after processing The results are illustrated in the appropriate tables and figures. Consequently the generalobservation that silk fabrics is flaccid is relevant only in terms of color. So for as Cutting-intensaty is concerned, it turned out to be less flaccid than in color. On the contrary when the untested silk thread was conpared with the xenon-irradiated ones, the latter proved itself to be more flaccid in cutting expansibility than the former. We have learned through this experiment that, after the all rounds of this test, the color tone and chroma of the colored materials remained without significant change, where as their color value changed to a large extent.

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    Adhesion of clay to metal surface; Normal and tangential measurement

    • Basmenj, Amir Khabbazi;Ghafoori, Mohammad;Cheshomi, Akbar;Azandariani, Younes Karami
      • Geomechanics and Engineering
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      • v.10 no.2
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      • pp.125-135
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      • 2016
    • Adhesion in geotechnical engineering is the interaction between cohesive soil and a solid surface which can cause clogging in mechanized tunnelling through clayey formations. Normal piston pull out and modified direct shear tests were performed on clayey soil samples to determine which type of adhesion stress, normal or tangential, could be most effectively measured. Measured values for normal adhesion ranged from 0.9 to 18 kPa. The range of tangential adhesion was 2.4 to 10 kPa. The results indicate normal adhesion results were more accurate than those for the modified direct shear test that measure tangential adhesion. Direct shear test on identical samples did not show any correlation between measured cohesion and normal adhesion values. Normal adhesion values have shown significantly meaningful variation with consistency index and so are compatible with the base of field clogging assessment criteria. But tangential adhesion and cohesion were not compatible with these assessment criteria.

    Dynamic behavior analysis of the high speed EMC(Electric Multiple Unit) (동력분산형 고속철도의 주행성능 해석기술 연구)

    • Yoon, Ji-Won;Park, Tae-Won;Lee, Moon-Gu;Jun, Kab-Jin;Park, Sung-Moon;Kim, Jung-Bum
      • Proceedings of the KSR Conference
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      • 2008.06a
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      • pp.1160-1165
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      • 2008
    • The development of a new railway vehicle is under progress through the Next Generation High-Speed Rail Development Project in Korea. Its aim is to develope fundamental technology of the vehicle that can run over 400km/h. The new distributed traction bogie system, 'HEMU'(High-speed Electric Multiple Unit), will be used and is different from previously developed high speed railway vehicles. Previous vehicles adopted push-pull type system, which means one traction-car drives rest of the vehicle. Due to the difference, investigation on dynamic behavior and its safety evaluation are necessary, as a part of verification of the design specification. In this paper, current progresses of researches are presented. And the High-Speed Railway vehicle system is evaluated for a dynamic characteristic simulation. Proper models including air-suspension system, wheel-rail, bogie and car-body will be developed according to the vehicle simulation scenario. International safety standard will be applied for final verification of the system. This research can propose a better solution when test running shows a problem in the parts and elements. Finally, the vehicle that has excellent performance will be developed, promoting academic achievement and technical development.

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