• 마이크로전자및패키징학회지
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• 제17권2호
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• pp.41-47
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• 2010

PCB와 BGA 패드의 형태가 무연솔더 접합부의 기계적 특성에 미치는 영향을 연구하었다. 현재 BGA/PCB 패드의 형태는 NSMD (Non-Solder Mask Defined)와 SMD (Solder Mask Defined) 두 가지 구조로 형성되어 있다. 본 연구에서는 OSP 도금처리한 무연솔더(Sn-3.0Ag-0.5Cu, Sn-1.2Ag-0.5Cu)의 패드 형태를 NSMD, SMD로 달리하여 낙하충격시험, 굽힘충격시험, 고속전단시험을 통한 솔더 접합부의 기계적 특성을 연구하였다. 낙하충격과 굽힘충격시험의 경우 패드 구조에 따른 솔더볼 접합부의 특성수명은 동일한 경향을 나타내었으며, 솔더접합부의 기계적 특성은 SMD가 NSMD보다 우수하였다. 이 이유는 SMD의 경우 낙하충격 시험과 고속 전단시험 모두 IMC에서 파단이 일어난 반면에 NSMD의 경우 낙하충격 시험 후의 파단면은 패턴을 감싸고 있는 랜드 상단 모서리 부분에서 파단이 일어났기 때문인 것으로 판단된다. 전단시험의 경우에는 NSMD 접합부에서 패드 lift현상이 발생하였다. 따라서 BGA/PCB의 패드구조의 조합은 SMD/SMD > SMD/NSMD > NSMD/SMD > NSMD/NSMD 순으로 기계적 특성 수명이 우수하였다.

• The Korean Journal of Pain
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• 제28권4호
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• pp.275-279
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• 2015

Facet joint synovial cysts are usually associated with osteoarthritis of the adjacent facet joint and/or spondylolisthesis. In between the conservative and operative ends of the treatment spectrum lie minimally invasive techniques such as cyst rupture using epiduroscopy. In this report, we describe an 82-year-old male patient presenting with low back pain radiating to his lower left extremity and associated paresthesia. Magnetic resonance imaging of the lumbar spine revealed a synovial cyst at left L4/5 facet joint. Using epiduroscopy, the cyst was mechanically ruptured by popping it with the tip of the scope. The patient remained symptom-free at his successive visits until 12 months after the procedure, and was opened for desired follow up.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.513-518
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• 1998

In this paper, a robust fault-tolerant control scheme for robot manipulators overcoming actuator failures is presented. The joint(or actuator) fault considered in this paper is the free-swinging joint failure and causes the loss of torque on a joint. The presented fault-tolerant control framework includes a normal control with normal(non-failed) operation, a fault detection and a fault-tolerant control to achieve task completion. For both no uncertainty case and uncertainty case, a stable normal con-troller and an on-line fault detection scheme are presented. After the detection and identification of joint failures, the robot manipulator becomes the underactuated robot system with failed actuators. A robust adaptive control scheme of robot manipulators with the detected failed-actuators using the brakes equipped at the failed(passive) joints is proposed in the presence of parametric uncertainty and external disturbances. To illustrate the feasibility and validity of the proposed fault-tolerant control scheme, simulation results for a three-link planar robot arm with a failed joint are presented.

• 마이크로전자및패키징학회지
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• 제12권1호
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• pp.65-71
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• 2005

At present, Electronic industries push ahead to eliminate the Pb(Lead) -a hazardous material-from all products. Especially, we have performed to select the optimum standard composition of lead free alloy for the application to products for about 3 years from 2000. These days, we have the chance for applying to the mass-production. This project constructed the system for applying the lead free solders on consumer electronic products, which is one of the major products of the LG Electronics. To select the lead free solders with corresponding to the product features, we have passed through the test and applied with Sn-3.0Ag-0.5Cu alloy system to our products, and for the application to the high melting temperature composition, we secured the thermal resistance of the many parts and substrate and optimized the processing conditions. We have operated the temperature cycling test and the high temperature storage test under the standards to confirm the reliability of the products. On these samples, we considered the consequence of our decision by the operating test. For the long life time of the product, we have operated the temperature cycling test at $-45^{\circ}C\;-\;+125^{\circ}C$, 1 cycle/hour, 1000 cycles. Also we have tested the tin whisker growth about lead free plating on lead finish. We have analyzed with the SEM, EDS and any other equipment for confirming the failure mode at the joint and the tin whisker growth on lead free finish.

• Journal of Oral Medicine and Pain
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• 제18권2호
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• pp.43-53
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• 1993

The aim of this study was to investigate the relationship between the presence or absence of anterior tooth contact and the changes in temporomandibular joint space. The study sample consisted of 32symptom-free dental students and 79 craniomandibular disorders patients with unilateral joint dysfunction. The two groups were categorized into control group or experimental group, respectively. Recordings of the number and distribution of occlusal contacts were made by T-Scan system. Transcranial radiographs were taken with using of accurad-100 head positioner. Measured items in transcranial radiographs were anterior, superior, posterior joint space and relative condylar position to deepest position of glenoid folla. According to the presence or absence of anterior tooth contact, each group was subdivided and compared with each other with respect to TM joint space. Data were processed and tested with SPSS/PC + package. The results of the study showed that the joint space in control group were wider than those of experimental group and the difference of the width of joint space was more remarkable in subjects with anterior contact between control group and experimental group. However, in same group whether the presence of anterior tooth contact could hardly affect the difference of the width of joint space. And anterior tooth contact in grouip are more frequent than in experimental group.

• 청정기술
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• 제11권3호
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• pp.153-164
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• 2005

This study found a reliable evaluation for four kinds of pb-Free plating solutions and it's layers, through pure Sn, SnAg, SnBi and SnCu. These four kind of solutions are widely used to pb-Free plating. Hull-cell, Harring-blum, coverage, throwing power, current efficiency, stability, life-time, composition, hardness, roughness, abrasion, scratch, solderability, corrosion, contact angle, morphology, SIR(Surface insulation resistance) and Whisker test were experimented. Also, Using ICP, XRF, FE-SEM, EDS, temperature/humidity chamber, solderability tester, hardness tester, roughness tester, abrasion tester, salt spray tester, contact angle tester, SIR tester, and microscope. In this paper could be shown the systematic and various analysis for reliability about four kinds of pb-Free plating solutions, processes and it's deposit surface.

• 무역상무연구
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• 제18권
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• pp.159-188
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• 2002

International joint ventures are usually formed and managed by domestic companies and foreign investors for the common objectives. They offer an opportunity for each partner to benefit significantly from the comparative advantages of the other. Local partners bring knowledge of the domestic market; familiarity with government bureaucracies and regulations; understanding of local labor markets; and existing manufacturing facilities. Foreign partners can offer advanced process and product technologies, management know-how, and access to export markets. In Korea, joint ventures have been encouraged to usher in foreign investors with foreign currency capital badly needed during the IMF financial crisis. In the meantime, Korean laws and regulations with respect to joint ventures have been largely overhauled to promote foreign direct investment (FDI) both inbound and outbound. They include four types of FDI, i.e., acquisition of foreign stocks, provision of long-term loans, participation in joint operations like resources development, and establishment of foreign offices. From the legal point of view, the formal joint venture agreement must be an offspring of a series of tough negotiations between domestic and foreign partners. They usually stress the long-term relationship with the good will and dedication to each other, and restrict the free transfer of stocks. Both partners are earnestly interested in the ownership and management of the joint venture. So they keep a close eye on the articles of incorporation, changes of business environment, conflict resolution methods, transparency of accounting and other financial matters. When a multinational corporation (MNC) is involved in the joint venture, conflicts over management strategies, marketing and other issues take place more often than not between the MNC and local partners. We have to pay attention to joint ventures, particularly, in China and North Korea. As witnessed in other transition economies, China is eagerly bringing in foreign direct investments for the development of nation's economy. China encourages foreign investors to establish ordinary joint ventures, contractual joint ventures, solely invested foreign capital companies and jointly operated development companies with local partners. In North Korea, however, joint ventures have a different meaning like contractual joint ventures in China, in which North Korean partners have an initiative in the management. Rather, jointly operated companies or simply processing-for-wage companies are recommended in view of the unpredictable legal infrastructure in North Korea.

• 동력기계공학회지
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• 제21권1호
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• pp.57-62
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• 2017

The flexible joint with bellows and flange is made by welding bellows and flange in general. The welded parts cause a crack or demage in the flexible joint due to continuous vibration and fatigue limit. This paper is concerned with development of flexible joint with non-welded, free rotation of flange and non-packing to improve fatigue failure condition between bellows and flange. The support box and support plate that are components of press part are designed to compress fore-end of bellows only without demage of bellows. The production system of flexible joint is designed with piston attached on the compression side. The simulation is performed using Deform 3D software. As the result of simulation, the shape of compressed bellows was most proper in the compression power of $157kg{\cdot}f$ and any deformation has not occurred at a part besides fore-end. The result show that the production possibility of the designed flexible joint.

• 대한금속재료학회지
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• 제47권4호
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• pp.261-266
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• 2009

The mechanical and electrical properties of ball grid array (BGA) solder joints were measured, consisting of Sn-3.5Ag, with organic solderability preservative (OSP)-finished Cu pads and Electroless Nickel/Immersion Gold (ENIG) surface finishes. The mechanical properties were measured by die shear test. When ENIG PCB was upper joint and OSP PCB was lower joint, the highest shear force showed at the third reflow. When OSP PCB was upper joint and ENIG PCB was lower joint, the highest shear force showed at the forth reflow. For both joints, after the die shear results reached the highest shear force, shear force decreased as a function of increasing reflow number. Electrical property of the solder joint decreased with the function of increasing reflow number. The scanning electron microscope results show that the IMC thickness at the bonding interface gets thicker while the number of reflow increases.

• 대한인간공학회지
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• 제34권6호
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• pp.583-595
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• 2015

Objective: The purpose of this study was to determine the reliability of lower limb joint angles computed with the software ImageJ during jumping movements. Background: Kinematics is the study of bodies in motion without regard to the forces or torques that may produce the motion. The most common method for collecting motion data uses an imaging and motion-caption system to record the 2D or 3D coordinates of markers attached to a moving object, followed by manual or automatic digitizing software. Above all, passive optical motion capture systems (e.g. Vicon system) have been regarded as the gold standards for collecting motion data. On the other hand, ImageJ is used widely for an image analysis as free software, and can collect the 2D coordinates of markers. Although much research has been carried out into the utilizations of the ImageJ software, little is known about their reliability. Method: Seven healthy female students participated as the subject in this study. Seventeen reflective markers were attached on the right and left lower limbs to measure two and three-dimensional joint angular motions. Jump performance was recorded by ten-vicon camera systems (250Hz) and one digital video camera (240Hz). The joint angles of the ankle and knee joints were calculated using 2D (ImageJ) and 3D (Vicon-MX) motion data, respectively. Results: Pearson's correlation coefficients between the two methods were calculated, and significance tests were conducted (${\alpha}=1%$). Correlation coefficients between the two were over 0.98. In Vicon-MX and ImageJ, there is no systematic error by examination of the validity using the Bland-Altman method, and all data are in the 95% limits of agreement. Conclusion: In this study, correlation coefficients are generally high, and the regression line is near the identical line. Therefore, it is considered that motion analysis using ImageJ is a useful tool for evaluation of human movements in various research areas. Application: This result can be utilized as a practical tool to analyze human performance in various fields.