• 한국수학사학회지
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• 제17권2호
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• pp.97-103
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• 2004

이 논문에서는 다원환의 자유결합의 대수적 구조를 규명하여 분수확대체로서의 미분가군의 일반적인 특성을 연구하고 있다. 보편적 범주 내에서의 미분과 미분가군의 대수적 형태는 대수적 결합의 기본 원칙을 충실히 보존한다는 원칙을 밝혔을 뿐만 아니라 대수적 동형 개념으로 수학의 우주적 균형이론을 실질적으로 보여주고 있다.

• 통상정보연구
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• 제15권1호
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• pp.309-330
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• 2013

4개 국가의 지역 무역협정으로 시작된 환태평양연대협정(TPP)은 미국의 적극적 참여와 일본이 참여 의사를 밝히면서 거대규모의 무역협정으로 확대되었다. 한국은 아직 유보적인 입장이지만 미국의 꾸준한 요청과 아시아 태평양 지역을 아우르는 규모를 감안하여 참여를 타진할 것으로 생각된다. 미국이 주도하는 TPP의 협정내용은 기존에 체결된 FTA를 기반으로 하여 구성될 것으로 예상되고 있다. 꾸준한 발전이 기대되는 전자상거래 분야는 이를 선도하고 있는 미국이 자신들이 유리한 부분을 적극적으로 제시할 것으로 예상되는 바, 한국이 참여한다면 한 미 FTA 등의 기존 협정 분야에서 우리에게 유리했던 부분 등을 적극 제시하고 향후 한국이 전자상거래 시장을 선도하는 방향으로 협상에 임하는 것이 중요하다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권2호
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• pp.109-116
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• 2013

The solder is any of various fusible alloys, usually tin and lead, used to join metallic parts that provide the contact between the chip package and the printed circuit board. Solder plays an important role of electrical signals to communicate between the two components. In this study, two kinds of Ag-free solder as sample is made to conduct the thermal shock test and the high humidity temperature test. Low resistance is measured to estimate crack size of solder, using daisy chain. The low speed shear test is also performed to analyze strength of solder. The appropriate degradation model is estimated using the result data. Depending on the composition of solder, lifetime estimation is conducted by adopted degradation model. The lifetime estimated two kinds of Ag-free solder is compared with expected lifetime of Sn-Ag-Cu solder. The result is that both Ag-free composition are more reliable than Sn-Ag-Cu solder.

• 한국운동역학회지
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• 제33권4호
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• pp.128-136
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• 2023

Objective: The aim of this study was to investigate the effect of an 8-week closed kinetic chain typed Reformer and Chair Pilates exercise on static and dynamic lower limb alignment for healthy female adults. Method: Ten healthy young female adults without musculoskeletal injury history in last 6 months (Age: 29.3 ± 3.5 yrs., Height: 165 ± 3.4 cm, Body mass: 58.2 ± 5.4 kg) participated in this study. All participants asked to join the 8-week closed kinetic chain typed Reformer and Chair Pilates exercise, and the program was conducted for 60 minutes twice a week. Participants were asked to be measure a static Q-angle and performed free squat one week before and after the program. A 3-D motion analysis with 8 infrared cameras and 5 channels of EMG was executed in this study. The effectiveness of the training was evaluated by paired t-test, and the significance level was set at .05. Results: A significantly decreased in internal rotation angles was found at hip joint during free squat after the training. Also, significantly decreased in lateral rotation angles were found at knee and ankle joint during free squat after training. Finally, significantly decreased in muscle activations were found at adductor longus and peroneus longus during free squat after training. Conclusion: From results of our study, it is concluded that an 8-week closed kinetic chain typed Pilates exercise positively effect on lower limb alignment during dynamic movement.

• Journal of Welding and Joining
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• 제6권3호
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• pp.21-26
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• 1988

The behavior of angular distortion in butt joint wleding of thin plate structure is investigated with an experimental model and partially with a computational model. The experimental model studying the effects of specimene size and degree of restraint on the angular distorion offers a good method for analyzing the behavior of the distrotion. In addition, the distrotion during welding was demonstrated by both experimental measurement and numericla prediciton. The facts evealed in this study are as follows : 1) distrotion angles were changed with variations of specimene wldth. 2) With the restraint, angular distrotion was reduced to 20% to that of free joint. 3) After the restraint being removed, the effect of restraint was also remained. 4) Same heat input per unit thickness caused same amount of distortion. 5) The mode of angular distortion was expected to be changed with expected to be changed with time, i.e. convex movement during heating and concave one during cooling.

• 한국정밀공학회지
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• 제12권2호
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• pp.112-122
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• 1995

While many surfaces such as automobile outer panels, ship hulls and airfoils are characterized by their smooth, free-form shapes, a far larger class of functional surfaces are characterized by highly irregular, multi-featured shapes consisting of pockets, channels, ribs, etc. In constaract to the design of aesthetic, free-form surfaces, functional surface design can perhaps best be viewed as a process of assembling a collection of known component surfaces to form a single compound surface. In this paper, we presents a feature-based functional surface modeling method. A single feature involves a secondary surface, which we must join to a primary surface with a smooth transition between two boundary courves. Through recursive blending of a secondary surface with the primary surface, the mullti-featured surface is represented. After constructing a compound surface, we generate the Z-map for NC machining of the surface. Offsetting the Z-map using the inverse offsetting technique, we get CL tool paths with out gouging.

• 마이크로전자및패키징학회지
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• 제20권4호
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• pp.65-68
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• 2013

A novel bumping process using solder bump maker (SBM) is developed for fine-pitch flip chip bonding. It features maskless screen printing process. A selective solder bumping mechanism without the mask is based on the material design of SBM. Maskless screen printing process can implement easily a fine-pitch, low-cost, and lead-free solder-on-pad (SoP) technology. Its another advantage is ternary or quaternary lead-free SoP can be formed easily. The process includes two main steps: one is the thermally activated aggregation of solder powder on the metal pads on a substrate and the other is the reflow of the deposited powder on the pads. Only a small quantity of solder powder adjacent to the pads can join the first step, so a quite uniform SoP array on the substrate can be easily obtained regardless of the pad configurations. Through this process, an SoP array on an organic substrate with a pitch of 130 ${\mu}m$ is, successfully, formed.

• East Asian Economic Review
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• 제17권4호
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• pp.333-359
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• 2013

Two mega-regional negotiations are changing the landscape of Asia Pacific trade policy: an Asian track centered on ASEAN (the Regional Comprehensive Economic Partnership or RCEP), and a Trans-Pacific track centered on the Trans-Pacific Partnership (TPP) among 12 economies, including the United States, which Korea is expected to join. Modeling results suggest that both would generate substantial benefits for Korea and the global economy. From Korea's viewpoint, the agreements would establish new FTAs with China, Japan and smaller economies, improve the utilization of FTAs by permitting the regional cumulation of inputs, and help to upgrade some Korean FTAs to more rigorous standards. By participating in these agreements, Korea could also help to guide them toward inclusive, high-quality regional outcomes. As one of the region's most open and agile economies, Korea has a large stake in regional integration and would be well advised to pursue both tracks.

• 대한수학회논문집
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• 제11권2호
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• pp.481-493
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• 1996

We consider a retrial queue with two classes of customers where arrivals of class 1(resp. class 2) customers are MMPP and Poisson process, respectively. In the case taht arriving customers are blocked due to the channel being busy, the class 1 customers are queued in priority group and are served as soon as the channel is free, whereas the class 2 customers enter the retrial group in order to try service again after a random amount of time. We consider the following retrial rate control policy, which reduces their retrial rate as more customers join the retrial group; their retrial times are inversely proportional to the number of customers in the retrial group. We find the joint generating function of the numbers of custormers in the two groups by the supplementary variable method.

• Korean Journal of Acupuncture
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• 제20권3호
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• pp.91-99
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• 2003

Effects of cheungho aqua-acupuncture at gansoo$(BL_{18})$ and illweul$(GB_{14})$ on plasma lipid composition were investigated in rat fed high fat diet. Body weight gain showed a tendency to decrease in aqua-acupuncture groups and in aqua-acupuncture groups, gansoo and illweul join aqua-acupuncture group showed a lower values than other aqua-acupuncture groups. Concentrations of plasma triglyceride, free fatty acids, lipoprotein and glucose showed a tendency to decreasea in the aqua-acupuncture groups. However in aqua-acupuncture groups, these values showed no significantly different. In plasma lipid composition, total cholesterol and LDL- cholesterol showed a tendency to decrease in aqua-acupuncture groups, however the values of LDL-cholesterol showed no significantly different in the aqua-acupuncture groups. HDL-cholesterol concentration showed a tendency to increase in aqua-acupuncture groups and in aqua-acupuncture groups, gansoo aqua-acupuncture group showed a high value.