• Journal of Welding and Joining
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• v.29 no.6
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• pp.71-76
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• 2011

Submerged arc welding method from both sides is generally applied to the welding of main panel manufacturing process during ship construction. The tandem SAW method is applied to improve the productivity. The various weld defects that occur during tandem SAW method are melt through, incomplete penetration, undercut and overlap etc. It could be thought that the reasons for these defects are mainly lack of prediction ability for penetration depth and deposited metal area. In this research, total 5 kinds of welding factors for experiment like current of lead pole, voltage of lead pole, current of trail pole, voltage of trail pole and welding speed are adopted. Weld tests are carried out for the analysis of variation effects of these factors on penetration depth and deposited metal area. Based on the test and analysis results, it is possible to obtain the prediction equation for the effect of these factors on the amount of deposited metal and penetration depth. As per the verification of the results by additional tests, it is confirmed that the prediction equation, include a error margin of ${\pm}2mm$ for penetration depth and ${\pm}10mm2$ for deposited metal area.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.2
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• pp.104-112
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• 2012

The failure of tenon in a traditional wood-framed structure may collapse of the entire structure. This study evaluates the strength and stiffness of tenon joints between the beams and pillars through experimental study and suggests reinforcing method of the tenon joint without dismantling the main structures. The main experimental parameters are the number, distance, shape, and inserting depth of spiral-shaped reinforcing steels. As the thickness of the tenon in beams increases, the strength and the initial shear stiffness of the joint increases and, however, the tenons in pillar becomes weaker, resulting in the safety problem of the structure. It is recommended that three spiral-shaped reinforcing steels be placed in the central parts of the tenon to effectively improve the strength and the shear stiffness of the joint.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.10
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• pp.98-104
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• 2020

Recently, friction stir welding of dissimilar materials has become one of the biggest issues in lightweight and eco-friendly bonding technology. In this study, a lightweight torsion beam axle, which is an automobile chassis component, was used in the welding to cast aluminum material. The friction stir welding process of A357 cast aluminum and FB590 high-strength steel as well as the effects of the process parameters were investigated and optimized using a novel definitive screening design (DSD). ANOVA was used to predict the importance of the process parameters with 13 degradation experiments using the proposed DSD. Also, FSWed experiments were conducted using an optical microscope analysis to investigate the tensile strength behavior in the weld area. In addition to determining the interaction between the tool's rotational speed and the plunge speed, results indicate that the influence of the plunge depth was the most significant.

• Journal of the Korea Concrete Institute
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• v.13 no.6
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• pp.593-601
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• 2001

In RC structure, sufficient anchorage of reinforcement is necessary for the member to produce the full strength. Generally, conventional standard hook is used for the reinforcement's anchorage. However, the use of standard hook results in steel congestion, making fabrication and construction difficult. Mechanical anchor offers a potential solution to these problems and may also ease fabrication, construction and concrete placement. In this paper, the required characteristics and the design considerations of mechanical anchor were studied. Also, the mechanical anchor was designed according to the requirements. To investigate the pull-out behavior and properness of mechanical anchorage, pull-out tests were performed. The parameters of tests were embedment length, diameter of reinforcement, concrete compressive strength, and spacing of reinforcements. The strengths of mechanical anchor were consistent with the predictions by CCD method. The slip between mechanical anchor and concrete could be controlled under 0.2mm. Therefore, the mechanical anchor with adequate embedment could be used for reinforcement's anchorage. However, it was observed that the strength of mechanical anchors with short spacing of reinforcements was greatly reduced. To apply the mechanical anchor in practice (e.g. anchorage of the beams reinforcements in beam-column joint), other effects that affect the mechanical anchor mechanism, such as confinement effect of adjacent member from frame action or effects of shear reinforcement, should be considered.

• Journal of Periodontal and Implant Science
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• v.33 no.4
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• pp.739-745
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• 2003

Interleukine-1(IL-1)은 여러 가지 기능을 가진 싸이토카인으로써 미생물에 대한 면역반응을 일으킨다. IL-1의 유전자 다형성과 치주질환과의 관련성에 대한 많은 연구가 있어왔지만, 대부분이 백인을 대상으로 한 연구였다. 이후 중국인과 일본인을 대상으로 한 연구에서 IL-1의 유전자 다형성의 분포가 인종간에 차이를 보인다는 점이 발견되었다. 이번 연구에서는 치주적으로 건강한 한국인에서 IL-1${\beta}$-511, IL-1${\beta}$+3954, IL-1RN에 대한 유전자형의 분포를 조사하고자 하였다. 서울대학교 치과병원에 근무하는 치과의사, 치과위생사, 간호조무사 및 서울대학교 치과대학 4학년 학생 중 치주낭 깊이와 부착소실이 4mm 이하인 치주적으로 건강한 한국인 65명을 대상으로 하였다. IL-1${\beta}$-511, IL-1${\beta}$+3954, IL-1RN의 유전자 다형성은 분리한 DNA에 각 대립유전자에 특이성을 지닌 primer를 넣고 PCR(Polymerase Chain Reaction)법을 이용하여 증폭시킨후 전기영동법을 이용하여 각 대립유전자의 존재를 확인함으로써 결정하였다. IL-1${\beta}$-511 대립유전자 11, 대립유전자 12, 대립유전자 22의 유전자형에 대하여 각각 23.1%, 49.2%, 26.2%의 분포를 보였다. IL-1${\beta}$+3954의 유전자 다형성은 대립유전자 11, 대립유전자 12의 유전자형에 대하여 각각 89.2%, 10.8%의 분포를 보였으며, 대립유전자 22의 유전자형을 갖는 사람은 한명도 발견되지 않았다. IL-1RN의 유전자형은 5가지의 대립유전자 중에서 1, 대립유전자 2, 대립유전자 4만일 발견되었으며, 대립유전자 11, 대립유전자 12, 대립유전자 14의 유전자형이 86.2%, 12.3%, 1.5%로 분포하였다. 이를 바탕으로 각 대립유전자의 발생빈도 계산한 결과 IL-1${\beta}$-511에서는 대립유전자 1과 2의 비율이 거의 유사하였으나 (47.7%, 52.3%), IL-1${\beta}$+3954, IL-1RN에서는 대립유전자 1이 90%이상 발견되었으며, 또한 대립유전자 1외의 다른 대립유전자가 발견된 경우, 모두 이형접합체였다. 이 연구는 IL-1${\beta}$-511, IL-1${\beta}$+3954, IL-1RN에 대한 유전자형의 분포를 조사한 것으로 한국인에서 이들 유전자의 유전자형의 분포는 백인에서의 분포와 차이를 보이고 있었다. 이후 치주질환자의 유전자형 분포와의 비교로 치주질환과 IL-1${\beta}$-511, IL-1${\beta}$+3954, IL-1RN의 유전자다형성과의 관련성에 관한 추가적인 연구가 필요할 것으로 여겨진다.

• Journal of Welding and Joining
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• v.30 no.2
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• pp.59-64
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• 2012

Welding is an essential process in the automotive industry. Most welding processes that are used for auto body are spot welding and $CO_2$ welding are used in a small part. In production field, $CO_2$ welding process is decreased and spot welding process is increased due to welding quality is poor and defects are occurred in $CO_2$ welding process frequently. But $CO_2$ welding process should be used at robot interference parts and closed parts where spot welding couldn't. Because of the 0.65mm ~ 2.0mm thickness steel sheet were used in the automotive industry, poor quality of welding area such as burn through and under fill were happened frequently in $CO_2$ process. In this paper, we will study about the penetration depth which gives a huge impact on burn through changing a degree of base metal, welding position and torch angle. Voltage, current and welding speed were fixed but degree of base metal, welding position and torch angle were changed. And Cold- Rolled(CR) steel sheet was used. Penetration depth was analysed by multiple regression analysis to derive approximate calculations. And reliability of approximate calculations were confirmed through additional experiments. As the results of this research, we confirmed the effect of torch and plate angle to bead shape. And we present a possibility that can simulate more accurate to weld geometry, as deduced the verification equations that has tolerance of less than 21.69%.

• Journal of the Korean Geographical Society
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• v.49 no.2
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• pp.113-138
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• 2014

Despite the growing numbers of regional problems (e.g. conflicts between the state and localities, inter-local conflicts, etc.) associated with the state-led developmental projects, the Korean social sciences have been unable to offer satisfying explanations and solutions to the regional problems. This is mainly because the existing works, which have been taken captured by the assumptions of "methodological nationalism", significantly lack the socio-spatial understandings of the state actions and the relations between the state and localities, thereby seeing the issues of regional development mainly in terms of either the economic efficiency defined at the national scale, or the plan rationality of the national bureaucrats. With this problem orientation in mind, this paper aims to explore the ways in which the state and localities are interacting, conflicting and negotiating with one another through the mediation of the state-led developmental projects. Focusing on the developmental processes of Masan Export Processing Zone from the mid-1960s to the early 1970s, it examines the multi-scalar processes through which the state-led industrial complex developmental processes have been influenced by the complex and dynamic interactions among social forces and actors acting at diverse geographical scales (e.g. the global, national, local, urban, etc.). This analysis shows that the regional policies of the Korean developmental state were more heavily influenced by the interactions, contestations, and collaborations among social forces and actors, acting in and through the state, at various geographical scales, rather than by the economic and techno-bureaucratic rationality.

• The korean journal of orthodontics
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• v.28 no.3 s.68
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• pp.431-440
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• 1998

While periodontal disease results in the extrusion of upper incisors with interdental spacing in adult patient, the intrusive movement should be executed for the rehabilitation in terms of esthetics and function. The present study was peformed to investigate the periodontal response following orthodontic intrusion of teeth with infrabony pocket. Bone defect and periodontal disease were produced adjacent to the both maxillary second lateral incisors in four adult dogs. Four weeks later, a flap operation was performed to eliminate inflammation and a reference notch was made on the root surface at the level of bottom of each defect. Two weeks after periodontal surgery, 4 weeks of intrusion and subsequent another 4 weeks of retention was executed on the right side of incisors while left incisors served as the control. Through the histologic analysis, following results were obtained. 1. Histologic section of control side showed the reduction of pocket depth after flap operation. However, the status of long junctional epithelium was observed while new connective tissue attachment occurred in a small area adjacent newly formed cementum 2. Epithelial attachment was less around the intruded incisor while new connective tissue attachment was much more compared to the control side. 3. Plenty of cells were observed in the connective tissue around the reference notch of the intruded incisor and the degree of the new cementum formation was higher in the intruded incisor than the control. The results of the present study suggested that an orthodontic intrusion of periodontally involved and extruded incisors could be carried out with a desirable periodontal response, provided that inflammation is under control.

• Journal of the Korea Concrete Institute
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• v.28 no.3
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• pp.365-373
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• 2016

Ultra-High-Performance Steel Fiber-Reinforced Concrete (SUPER Concrete) exhibits improved compressive and tensile strengths far superior to those of conventional concrete. These characteristics can significantly reduce the cross sectional area of the member and the anchorage strength of a headed bar is expected to be improved. In this study, the anchorage strengths of headed bars with $4d_b$ or $6d_b$ embedment length were evaluated by simulated exterior beam-column joint tests where the headed bars were used as beam bars and the joints were cast of 120 or 180 MPa SUPER Concrete. In all specimens, the actual yield strengths of the headed bars over 600 MPa were developed. Some headed bars were fractured due to the high anchorage capacity in SUPER Concrete. Therefore, the headed bar with only $4d_b$ embedment length in 120 MPa SUPER Concrete can develop a yield strength of 600 MPa which is the highest design yield strength permitted by the KCI design code. The previous model derived from tests with normal concrete and the current design code underestimate the anchorage capacity of the headed bar anchored in SUPER Concrete. Because the previous model and the current design code do not consider the effects of the high tensile strength of SUPER Concrete. From a regression analysis assuming that the anchorage strength is proportional to $(f_{ck})^{\alpha}$, the model for predicting anchorage strength of headed bars in SUPER Concrete is developed. The average and coefficient of variation of the test-to-prediction values are 1.01 and 5%, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.3
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• pp.79-84
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• 2010

Formation of TSV (Through-Si-Via) with an Au seed layer and Cu filling to the via, simplification of bumping process for three dimensional stacking of Si dice were investigated. In order to produce the via holes, the Si wafer was etched by a DRIE (Deep Reactive Ion Etching) process using $SF_6$ and $C_4F_8$ plasmas alternately. The vias were 40 ${\mu}m$ in diameter, 80 ${\mu}m$ in depth, and were produced by etching for 1.92 ks. On the via side wall, a dielectric layer of $SiO_2$ was formed by thermal oxidation, and an adhesion layer of Ti, and a seed layer of Au were applied by sputtering. Electroplating with pulsed DC was applied to fill the via holes with Cu. The plating condition was at a forward pulse current density of 1000 mA/$dm^2$ for 5 s and a reverse pulse current density of 190 mA/$dm^2$ for 25 s. By using these parameters, sound Cu filling was obtained in the vias with a total plating time of 57.6 ks. Sn bumping was performed on the Cu plugs without lithography process. The bumps were produced on the Si die successfully by the simplified process without serious defect.