• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.2
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• pp.175-188
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• 2009

The purpose of this study was to find a method for improving children's preferences during dental treatment in relation to dentist's attire. For this study, 650 children asked to participate in a survey about the attire of the dentists. The results of the survey were as follows: 1. The survey found that gowns were preferred to ordinary clothes for both male and female dentists, 67.7 to 87.6% for male and 59.2 to 75.9% for female dentists. 2. For male dentists, the typical long white gown was the most preferred style, followed by a long gown, and a short jacket type, and then a short operating gown. 3. For female dentist, the typical long white gown was also most preferred, followed by a long gown, a short jacket type, and then a short operating gown. 4. For dental hygienists, the most preferred attire style was a two-piece wear with pants, followed by one-piece, skirt suit, shirts with cartoon characters, and apron. However, the difference among these attires was insignificant 5. White was the preferred color for gown. 6. Children prefer gown with no-pattern.

• Journal of the Korean Institute of Gas
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• v.21 no.6
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• pp.52-60
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• 2017

In diffusion process exhaust line during semiconductor manufacturing process, In order to improve the transportation efficiency in the piping by removing "The reaction by-product, $ZrO_2$ and The unreacted material, TEMAZ, TMA, $O_3$, etc" and "Powder being deposited", the piping temperature was raised to $80^{\circ}C$ or more by using the heater jacket, and the bellows at the rear end of the vacuum pump ruptured. So conducted a case study and try to prevent the similar accidents from occurring through case studies. The causes of the accident were analyzed as follows: the inflow of outside air due to the generation of a gap on the suction side of the vacuum pump and heating the pipe with the heater jacket resulted in the overpressure in the pipe due to the volumetric expansion of the gas generated by decomposition of the unreacted TEMAZ, It can be assumed that the most vulnerable bellows of the piping has been ruptured. In order to prevent such accidents, This study is aimed to identify the cause of pipeline rupture accident and to establish safety measures for the prevention of similar accidents by evaluating physical hazards of TEMAZ, which is assumed to be the cause of pipe rupture accident.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.263-270
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• 2021

In this study, a reliability-based design optimization of a 130-m class fixed-type offshore platform, to be installed in the North Sea, was carried out, while considering environmental, material, and manufacturing uncertainties to enhance its structural safety and economic aspects. For the reliability analysis, and reliability-based design optimization of the structural integrity, unity check values (defined as the ratio between working and allowable stress, for axial, bending, and shear stresses), of the members of the offshore platform were considered as constraints. Weight of the supporting jacket structure was minimized to reduce the manufacturing cost of the offshore platform. Statistical characteristics of uncertainties were defined based on observed and measured data references. Reliability analysis and reliability-based design optimization of a jacket-type offshore structure were computationally burdensome due to the large number of members; therefore, we suggested a method for variable screening, based on the importance of their output responses, to reduce the dimension of the problem. Furthermore, a deterministic design optimization was carried out prior to the reliability-based design optimization, to improve overall computational efficiency. Finally, the optimal design obtained was compared with the conventional rule-based offshore platform design in terms of safety and cost.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1065-1072
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• 2010

The excavation site in the new city of inchon songdo is distributed with soft reclaimed soil and marine deposit. So, the general ground anchor is not applied to this layer of soft ground as the earth retaining support system, because of settlement. And then, Jacket pack anchor which is newly developed in order to increasing the pullout resistance by certain grout bulb formation and expansion effect in soft ground is applied to this site instead of the general ground anchor. Though the maximum horizontal displacement shows about 30mm~100mm (The maximum horizontal displacement/excavation depth$\fallingdotseq$0.32~1.0%) according to excavation sequence, generally excavation work finished stably. Also, load cell after setting shows almost increasing trend with increasing horizontal displacement. It means that the settlement of Jacket pack anchor in soft ground is good. From the result of this case, we knew that Jacket pack anchor was able to use the earth retaining support system in soft ground. Using Jacket pack anchor in soft ground, The allowance of the horizontal displacement is applied more than general value considering soil factors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05e
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• pp.44-48
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• 2003

할로겐 난연재료 및 고분자의 연소시 Dioxine의 문제점이 대두되고 있어 유럽국가를 중심으로 할로겐 난연제 사용을 규제하고 있다. 환경과 인체에 대한 안정성을 고려해서 저 유해 가스화, 저 발연화, 저 부식성, 리사이클링 등을 겸비한 제품의 개발로 관심이 모아지고 있는 실정이다. 본 연구에서는 환경친화적인 금속화합(수산화 알루미늄)을 사용하여 연소시 발생할 수 있는 난연성, 무독성, 소연성 등을 함량별로 확인하고 난연재가 증가할수록 취약한 기계적 물성 보완을 위해 moisture cure crosslikable 기술로 케이블절연 및 자켓 피복층 특성을 증가 시켰다. 그러나 수산화알루미늄 함량이 증가할수록 기계적 물성과 기타 특성도 감소하는 경향을 보이고 있어 최적의 난연제 조성함량이 약 130~150 phr정도에서 우수한 결과를 확인하였다. 또한 moisture cure agent는 전선압출 시 표면에 scorch 및 장기 압출에 영향을 주므로 약 1.5~2phr 범위에서 처방하는 것이 우수하다. 원료투입 후 mixing 공정 중에서는 온도관리가 매우 중요하므로 되도록 믹싱 온도를 $130^{\circ}C$ 이하를 유지해야한다. 온도는 수산화알루미늄의 분산성과 케이블 피복압출 시 표면에도 영향을 주기 때문이다 본 연구는 이런 작업방법을 통해 친환경 가교 난연콤파운드가 비(比) 가교된 제품에 비해 특성이 증가되는 것을 입증할 수 있었다.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.555-557
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• 2000

원자력 발전소에서 사용되어지는 케이블은 전원 및 제어신호를 안정하게 전달하는 역할을 하며, 비상상태 발생시에는 원자로를 안전하게 shut-down시키는 통로 역할을 하므로 매우 중요하다. 케이블 상태 감시시 절연 및 피복재료는 종류 및 배합내용이 다양하기 때문에 종래의 자료로부터 전선과 케이블의 열화 또는 수명을 추정하기가 극히 어려우며 방사선에 노출이 되는 케이블의 경우 노화현상의 진행이 빠르고 방사선 열화로 수명이 단축되므로 국내 실정을 감안한 독자적인 검증방법 도출, 규제기술 기반 구축 필요 및 규제의 합리화와 효율화 필요성이 대두되고 있다. 기존에 사용해온 케이블 진단 방법에는 절연 파괴 강도 측정을 통한 노화진단, 산화 방지능력 측정을 통한 노화진단, 자켓 및 절연체의 판단, 연신율에 의한 노화진단, 케이블 Indenter에 의한 노화진단, 온도 및 방사선 등의 특정상태에 대한 평가, 유사한 환경조건에 대한 주기적 검토 등이 있다. 기존의 국내외 케이블 상태 감시방법을 조사 연구하므로서 케이블 열화에 대비한 수명관리 규제 기술 및 상태감시 (Condition Monitoring : CM) 기술의 평가 기준을 결정 하고자 한다.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1240-1249
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• 2008

Jacket anchor was developed to increase the pullout resistance of general ground anchor in soft ground, and the mechanism of pullout resistance of jacket anchor was analyzed. Also, the ultimate bond stress of jacket anchor was estimated by ultimate resistance which is determined by field tests. Grout milk was injected into the jacket to make grout bulb of jacket anchor. The formation of grout bulb of jacket anchor increases the diameter of grout bulb, ground strength and confining pressure between anchor grout and soil. From the twelve field test results, it was observed that the pullout resistance of jacket anchor is 15.38~295.02%(average 83.53%) greater than that of general ground anchor, and plastic deformation of jacket anchor is 20.78~1,496.45%(average 288.78%) smaller than that of general ground anchor at the same load cycle. Especially, it was investigated that the increase of ultimate resistance over 200% and the reduction of plastic deformation over 600% was obtained in gravel layer. It means that the jacket anchor is superior to the general ground anchor in gravel layer. Finally, the ultimate bond stress was proposed to design jacket anchor.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.5
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• pp.281-289
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• 2018

Existing reinforced concrete building structures have seismic vulnerabilities due to their seismically-deficient details resulting in non-ductile behavior. The seismic vulnerabilities can be mitigated by retrofitting the buildings using a fiber-reinforced polymer column jacketing system, which can provide additional confining pressures to existing columns to improve their lateral resisting capacities. This study presents dynamic responses of a full-scale non-ductile reinforced concrete frame retrofitted using a fiber-reinforced polymer column jacketing system. A series of forced-vibration testing was performed to measure the dynamic responses (e.g. natural frequencies, story drifts and column/beam rotations). Additionally, the dynamic responses of the retrofitted frame were compared to those of the non-retrofitted frame to investigate effectiveness of the retrofit system. The experimental results demonstrate that the retrofit system installed on the first story columns contributed to reducing story drifts and column rotations. Additionally, the retrofit scheme helped mitigate damage concentration on the first story columns as compared to the non-retrofitted frame.

• Journal of the Korean Society of Clothing and Textiles
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• v.19 no.3
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• pp.525-535
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• 1995

This study was designed to verify the clothing satisfaction according to product type (jacket vs. pantyhose) and consumer fashion involvement. Research problems were as following; 1. To identify a clothing satisfaction according to product type. 2. To discover which of satisfaction relevant variables has the most influence on clothing satisfaction. 3. To examine the relationship between expectations and discontinuations. 4. To examine the degree of influence of product type and consumer fashion involvement on expectations. The survey was carried out in Pulsar shopping area. The 104 subjects (51 for jacket, 53 for pantyhose) participated in the final analysis. The results of analysis were as following; 1. The main path of clothing satisfaction was that the product type -1 the expectations -1 the perceived performance (-1 the discontinuation) -1 the clothing satisfaction. Those relevant variables explained 62% of clothing satisfaction variance. The most powerful determinant was the perceived performance. 2. For jacket type, the influence of perceived performance appeared to be greater than that of the discontinuation. And the consumer fashion involvement affected the expectations and the discontinuation. 3. For pantyhose type, the consumer fashion involvement divan't affect the expectations. The influence of discontinuation was relatively higher than that of jacket type.

• Journal of the Korean Institute of Gas
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• v.5 no.3 s.15
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• pp.55-62
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• 2001

This paper describes about the formation of methane hydrate that is artificially made in jacket-type stirred reactor and is observed the change of hydrate shape during the course of reaction. The combustion of manufactured methane hydrate is showed the probability of a storage and transport of gas. And the influence of various experimental conditions of temperature, pressure and stirring rate on the manufacture of methane hydrate is measured. The growth rate and the induction time of methane hydrate is observed according to the conditions. Especially it is important to investigate the effect of temperature and pressure on the growth of hydrate such as the nuclear creation and the structure formation of hydrate in order to study the storage and transport of gas.