• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.640-644
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• 2000

The microstructure, wettability, shear strength and aging effect of Sn-3.5Ag/Cu and Alloy42 lead-frame solder joints were measured for comparison. In the case of Sn-3.5Ag/Cu, Ag$_3$Sn and Cu$\sub$6/Sn$\sub$5/ phases in the matrix Sn and 1∼2$\mu\textrm{m}$ thick Cu$\sub$6/Sn$\sub$5/ Phase at the interface of solder/lead-frame were formed. In the case of Sn-3.5AAg/A11oy42, only Ag$_3$Sn Phase of low density in the matrix Sn and 0.5∼1.5$\mu\textrm{m}$ thick FeSn$_2$phase at the interface of solder/lead-frame were formed. Comparing to Cu, Alloy42 shear strength of Alloy 42 solder joints was smaller than that of Cu and all declined after aging. After aging at 180$^{\circ}C$ for 1 week, η-Cu$\sub$6/Sn$\sub$5/ layer was formed on Cu lead-frame, while AgSn$_3$ phase in the matrix and thickened FeSn$_2$at the interface were formed on Alloy42 lead-frame.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.11-17
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• 2009

The drop impact reliability comes to be important for evaluation of the life time of mobile electronic products such as cellular phone. The drop impact reliability of solder joint is generally affected by the kinds of pad and reflow number, therefore, the reliability evaluation is needed. Drop impact test proposed by JEDEC has been used as a standard method, however, which requires high cost and long time. The drop impact reliability can be indirectly evaluated by using high speed shear test of solder joints. Solder joints formed on 3 kinds of surface finishes OSP (Organic Solderability Preservation), ENIG (Electroless Nickel Immersion Gold) and ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) was investigated. The shear strength was analysed with the morphology change of intermetallic compound (IMC) layer according to reflow number. The layer thickness of IMC was increased with the increase of reflow number, which resulted in the decrease of the high speed shear strength and impact energy. The order of the high speed shear strength and impact energy was ENEPIG > ENIG > OSP after the 1st reflow, and ENEPIG > OSP > ENIG after 8th reflow.

• Tunnel and Underground Space
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• v.15 no.2 s.55
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• pp.119-128
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• 2005

Although the evaluation of the mechanical properties and behavior of jointed rock masses is very important for the design of tunnel and underground openings, it has always been considered the most difficult problem. One of the difficulties in describing the rock mass behavior is the selection of the appropriate constitutive model. This limitation may be overcome with the progress in discrete element software such as PFC, which does not need the user to prescribe a constitutive model for rock mass. In this paper, a 30\;m\;\times\;30\;m\;\times\;30\;m m jointed rock mass of road tunnel site was analyzed. h discrete fracture network was developed from the joint geometry obtained from core logging and surface survey. Using the discontinuities geometry from the DFN model, PFC simulations were carried out, starting with the intact rock and systematically adding the joints and the stress-strain response was recorded for each case. With the stress-strain response curves, the mechanical properties of jointed rock masses were determined. As expected, the presence of joints had a pronounced effect on mechanical properties of the rock mass. More importantly, getting the mechanical response of the PFC model doesn't require a user specified constitutive model.

• Fire Science and Engineering
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• v.26 no.4
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• pp.31-41
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• 2012

This study collected 5,100 cases of gas accident occurred in Korea for 14 years from 1995 to 2008, established Database and based on it, analyzed them by detailed forms and reasons. As the result of analyzing the whole city gas accidents with Poisson analysis, the item of "Careless work-Explosion-Pipeline' showed the highest rate of accidents for the next 5 years. And, "Joint Losening and corrosion-Release-Pipeline" showed the lowest rate of accident. In addition, for the result of analyzing only accidents related to LPG vaporizer, "LPG-Vaporizer-Fire" showed the highest rate of accident and "LPG-Vaporizer-Products Faults" showed the lowest rate of accident. Also, as the result of comparing and analyzing foreign LPG accident accompanied by Jet fire, facility's defect which is liquid outflow cut-off device and heat exchanger's defect were analyzed as the main reason causing jet fire, like the case of Korea, but the number of accidents for the next 5 years was the highest in "LPG-Mechanical-Jet fire" and "LPG-Mechanical-Vapor Cloud" showed the highest rate of accidents. By grafting Poisson distribution theory onto gas accident expecting program of the future, it's expected to suggest consistent standard and be used as the scale which can be used in actual field.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2402-2408
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• 2009

This study conducted a static tensile test in order to prevent the lowering of load carrying capacity caused by critical sections made by over bolt holes in the base plate and the cover plate of steel member joints using high-tension bolts. The change of the load carrying capacity of joints was examined by comparison of the maximum load on joint fracture obtained from the tensile test with critical section rate and design strength. According to the results, the rate of decrease in strength was higher when the critical section rate was high, and in particular, decrease in strength was affected much more by critical sections in the base plate than by those in the cover plate. In high-tension bolt joints using over bolt holes for the base plate and the cover plate, load carrying performance was somewhat lower than that in joints using standard bolt holes, but the maximum tensile strength on facture was over 15% higher than design fracture strength. According to the results of this study, the use of over bolt holes in high-tension bolt joints had an insignificant effect on the lowering of load carrying capacity, so the allowance of over bolt holes in the joints of steel members is expected to enhance to the economy and efficiency of the works.

• The Journal of the Korea Contents Association
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• v.9 no.6
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• pp.207-215
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• 2009

There has been a diversity of therapeutic interventions for patients with chronic low back pain. However most of them have been focused on only pain. But the patients usually have a kind of structurally abnormal have fixed in lumbar vertebrae, which can decrease range of joint movement and, what is worse, reduce immediate dynamic balancing ability(IDBA). The reduced IDBA can increase the risk of injury and decrease coping ability in dangerous situation. So we introduced Maitland's manual therapy in this study in order to recover the IDBA in patients with chronic low back pain. Sixty-four patients diagnosed with chronic low back pain were included for the study. Among them, thirty-two patients(experimental group) were managed by Maitland's manual therapy, another thirty-tow patients(control group) were treated by physical science methods(H/P, TENS, U/S). Each group made use of highly reliable(0.81$\sim$0.96) star excursion balance test(SEBT) to compare the possible changes of IDBAs in two groups after treatment. In experimental group, IDBA has increased in forward, rightward, leftward, and backward, but in control group, not changed. According to the results, we concluded that Maitland's manual therapy is effective for increasing IDBA by making joints more flexible in lumbar vertebrae.

• Review of Culture and Economy
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• v.17 no.2
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• pp.29-62
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• 2014

Game industry, one of cultural-content industry which is considered as a typical knowledge-based industry and creative industry, is not like the overseas expansion of traditional manufacture, and has different strategy and performance of export expansion through product or project-based strategy. Therefore, it should be approached by each content unit, and necessary to look at the factors that make their decision makings of foreign market entry vary. This study focuses on discovering creativity, absorptive capacity and strategic orientation(market orientation and innovation orientation) which affect the difference of distribution's decision making of entry into foreign market in game industry This paper examined 252 cases of online games in order to investigate creativity, absorptive capacity and strategic orientations for each foreign market and what entry type(among licensing, joint distribution, exclusive distribution) they chose according to the products developed in team level. This helps us analyze the factors affecting market orientation and innovation orientation in the perspectives of creativity and absorptive capacity in comprehensive way, and notice the phenomena which use different foreign distribution strategy though there are company incorporated abroad and their results. This study supplements the limit of the existing Resource-Based View, Resource-Dependent View, and traditional international business theories such as Transaction Cost Theory or OLI Paradigm(Eclectic Framework), and proves how company could reduce asymmetry of uncertainty and information in creative industry and whether they accomplish successful overseas expansion according to strategic orientations.

• Journal of the Korean Geophysical Society
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• v.9 no.2
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• pp.121-128
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• 2006

Recently, spillways are need to control stable water level for supporting main dams because of floods by unusual change of weather such as Typhoon Rusa. This study has been focused on the amount of leakage through the rock mass distributed fractures and joints under the opened emergency spillway. It is very important to evaluate the amount of leakage as these affect stability of spillway by interaction between effective stress and pore pressure. The commercial program MAFIC has been used for analyzing groundwater flow in fractured rock mass. The results showed that the values of range, average and deviation of leakage were 2.85∼ 3.79×10-1, 3.32×10-1 and 1.70×10-2 m3/day/m2 respectively. Secondary, we have estimated the effect of grouting after the transmissivity(Tf) of joint 1 as main pathway of leakage known from above results was changed from 1.78×10-7 to 1.59×10-9 m2/s. The results showed that the values of range, average and deviation of leakage were 7.80×10-4∼1.53×10-3, 1.18×10-3 and 1.32×10-4 m3/day/m2 respectively. As the result, the amount of leakage after grouting has been decreased by a ratio of 1 to 277.

• International Area Studies Review
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• v.22 no.4
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• pp.99-121
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• 2018

This study investigated the factors influencing the knowledge acquisition of Thai local partners from advanced foreign partners through international joint ventures(IJVs). For this purpose, this study initially identified three dimensions of characteristics in the context of IJVs that would influence local partners' knowledge acquisition - a local partners' own characteristic (absorptive capacity), a relationship characteristic with IJVs (proximity to the equal equity ownership), and a relationship characteristic with foreign partners (trust), and examined their effects on local partners' knowledge acquisition. The study further investigated the moderating effects of the tacitness of knowledge on the relationships between those characteristics and knowledge acquisition. Based on the data collected from Thai IJV local partners, results revealed that a local partners' own characteristic, absorptive capacity, and a relationship characteristic with IJVs, proximity to the equal equity ownership, had a strong positive effect on local partners' knowledge acquisition. Results further showed that the tacitness of knowledge strengthened the relationships between absorptive capacity and knowledge acquisition and between trust and knowledge acquisition, but not the relationship between proximity to the equal equity ownership and knowledge acquisition.

• Management & Information Systems Review
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• v.37 no.4
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• pp.141-156
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• 2018

PMO(Project Management Office) has been considered as a general approach for the successful operation of IT project. The previous studies tended to emphasize on the roles and functions of PMO in a normative way. However, in practice, since PMO is operated as a joint structure in which client firms and professional PMOs work together, it seems to be important that the implementation system of PMO should be properly formed. In this paper, it is examined whether the competence of client firms and professional PMO influence on the setup of implementation system of PMO, and also whether implementation system of PMO influence of the performance of IT project. In addition, it is also analyzed if the competence of client firms and professional PMO influence differently on the setup of implementation system of PMO, according to the degree of knowledge complementarity. As a result of this study, it is found that the competence of client firms and professional PMO influence positively on the setup of implementation system of PMO, and governance factors such as clear definition of organizational roles, responsibility, and setup of standardized processes are also important in performance of IT project. It is also shown that, if knowledge complementarity is formed with a common knowledge base between client firms and professional PMOs, Project Management Office functions effectively. In summary, for the successful performance of IT project, it seems that it is required to approach from the view point of governance in forming the implementation system of PMO and it is also important to form knowledge complementarity between client firms and professional PMOs.