• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.6
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• pp.278-285
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• 2006

Coating mixtures of the resin B-H for the application to the desulfurization system of power plant were coated on carbon steels and cured at the temperature of $65^{\circ}C{\sim}80^{\circ}C$. After being contacted with 70wt% $H_2SO_4$ solution of $100^{\circ}C\;and\;120^{\circ}C$ for several hours, their composition, Vicker's hardness and microstructures by SEM were examined. Corrosion resistance of the coating mixtures to $H_2SO_4$ solution was related to the content of $SO_3$ in the coated specimens after corrosion test. The lower curing temperature and the shorter curing time the coated specimens went through, the higher corrosion resistance to acid they showed, but the more cracks were developed at higher temperature. It was realized that the corrosion resistance to sulfaric acid solution was increased on the condition of curing temperature above $65^{\circ}C$ and curing time above 12 hours at least.

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.344-352
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• 2010

Objectives: The purpose of this study was to determine the setting time, compressive strength, solubility, and pH of mineral trioxide aggregate (MTA) mixed with glass ionomer cement (GIC) and to compare these properties with those of MTA, GIC, IRM, and SuperEBA. Materials and Methods: Setting time, compressive strength, and solubility were determined according to the ISO 9917 or 6876 method. The pH of the test materials was determined using a pH meter with specified electrode for solid specimen. Results: The setting time of MTA mixed with GIC was significantly shorter than that of MTA. Compressive strength of MTA mixed with GIC was significantly lower than that of other materials at all time points for 7 days. Solubility of 1 : 1 and 2 : 1 specimen from MTA mixed with GIC was significantly higher than that of other materials. Solubility of 1 : 2 specimen was similar to that of MTA. The pH of MTA mixed with GIC was 2-4 immediately after mixing and increased to 5-7 after 1 day. Conclusions: The setting time of MTA mixed with GIC was improved compared with MTA. However, other properties such as compressive strength and pH proved to be inferior to those of MTA. To be clinically feasible, further investigation is necessary to find the proper mixing ratio in order to improve the drawbacks of MTA without impairing the pre-existing advantages and to assess the biocompatibility.

• Journal of Industrial Technology
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• v.36
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• pp.45-48
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• 2016

The purpose of this study is to evaluate and compare wettability and setting time of twelve polyvinylsiloxane impression pastes. For comparing the wettability, the contact angle of a water drop on the impression materials was measured. It is important for impression materials to have higher wettability when trying to make impressions of interproximal spaces and gingival crevices. The higher wettability the better the material will flow into these spaces and the more accurate the impression. An ideal impression material will have adequate working time but a fast intraoral setting time. The clinician needs time to inject material into the sulcus, place the impression material into the tray and position it in the mouth, but the material should set rapidly to reduce time in the patient's mouth. It is considered that the results obtained in this study will provide guideline information for the manufacturing of impression materials and for selecting appropriate impression materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.497-498
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• 2009

Unsaturated polyester(UP) and epoxy resin require 8${\sim}$11 hours long harding times and heating systems used by reinforcement liner. This study is to evaluate the effects of low temperature harding property of UP with methyl methacrylate(MMA) monomer mixing proportions.

• Conservation Science in Museum
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• v.14
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• pp.29-35
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• 2013

In cases, such as white porcelain with openwork lotus scroll design, where the ceramics has intricate form and decorations, we normally use casts to restore the work, in that current restoration materials have short molding time which causes difficulties in delicate work. However, since using a cast for restoration requires longer work-time and uses more materials, we decided to restore in direct. Since the molding time in the restoration material is closely related to the workability, restoration material which secures longer work hours is necessary when directly restoring a complex form of body. Therefore we experimented on the work-time, color variation and workability as time passes by making mixtures of Epoxy putty and Baked clay in different ratios. As a result of the experiment, the mixture ratio of OS8:RQ2 turned out to be the most effective ratio.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2002.05a
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• pp.139-147
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• 2002

• 대한치과보철학회:학술대회논문집
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• 2005.11a
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• pp.59-59
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• 2005

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.65-68
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• 2007

저온 플라즈마 기술을 이용하면 오스테나이트계 스테인리스강의 내식성과 표면경도를 동시에 증가 시킬 수 있다. 여러 가지 처리방법 중 질탄화와 2-step 공정으로 처리한 AISI304L강의 표면을 분석하였다. 처리한 모든 시편의 표면은 expanded austenite(${\gamma}_N$)이 형성되었고, 표면 경도도 모재보다 약 4배 이상 증가 하였다. 저온플라즈마 질탄화 공정의 경우 경화층의 두께가 최대 15 ${\mu}m$밖에 형성되지 않았지만 2-step공정의 경우 질탄화 공정보다 짧은 시간으로 약 2배의 경화층을 얻을 수 있었다. 두 가지 공정 모두 온도와 시간이 증가할수록 경화층의 두께가 두꺼워졌지만, 과도하게 높은 온도와 긴 공정시간은 석출물을 형성 시켰다. 석출물이 형성되지 않은 시편의 경우 내식성이 증가하였다.

• Journal of the Korea Concrete Institute
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• v.18 no.1 s.91
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• pp.117-124
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• 2006

The effects of binder content and recycling mixed waste plastics(PA) content on the workability, work life and hardening shrinkage of fresh polymer concrete using mixed waste plastics are examined. As a result, the workability of the polymer concretes using mixed waste plastics tend to improve with increasing binder content, PA content and filler content. The work life of the polymer concretes using mixed waste plastics is shortened with an increase in the initiator content and curing temperature. The length change of the polymer concretes using mixed waste plastics tend to increased with Increasing binder content and PA content. The result of the present research is expected to make a contribution to the recycling of final mixed waste plastics and the continuing efforts for the development of use of the recycled products are thought to expand the horizon for the recycling of the final mixed waste plastics.

• Physical Therapy Korea
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• v.8 no.4
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• pp.71-80
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• 2001

근위축성 측색 경화증 (amyotrophic lateral sclerosis: ALS) 환자에게 있어 호흡기능장애는 죽음에 이르게 하는 주요 원인 중 하나이다. 본 연구는 근위축성 측색 경화증이 있으며 호흡기능이 약화되어 있는 51세의 여성 환자를 대상으로 호흡운동 치료를 시행한 후 폐기능(pulmonary function)이 증진되었는지를 알아보고자 실시하였다. 연구 대상자는 6주간의 호흡운동 치료 프로그램에 참여하였다. 호흡운동 치료 프로그램은 횡경막 호흡(diaphragmatic breathing), 복부근육강화(abdominal mu scles strengthening), 지갑입술 호흡(pursed lip breathing), 그리고 동기 유발성 흡기폐활량계(incentive spirometer)를 이용한 흡기운동 등으로 구성되었다. 폐기능 검사는 이동식 호흡측정기(spirometer: MICROSPIROHI-198)를 이용해서 시행하였다. 또한 하지 에르고미터(cycle- ergometer)를 이용해 운동 시간을 측정함으로써 폐기능의 증진 여부를 알아보았다. 연구 대상자는 6주간의 호흡운동 치료 기간 동안 노력성 폐활량(forced vital capacity: FVC)과 정상 예측치에 대한 노력성 폐활량의 비율(percentage of the predicted forced vital capacity: %FVC), 그리고 하지 에르고미터의 운동 시간에 있어 현저한 증가를 보였다. 그러나 노력성 폐활량에 대한 1초간 노력성 폐활량 비(FEV1/ FVC)에 있어서는 약간의 감소를 보였다. 근위축성 측색 경화증 환자에게 6주간의 호흡운동 치료를 실시한 결과, 폐기능의 증진에 효과적임을 알 수 있었으며, 앞으로 더 많은 연구 대상자에게 그 효과를 알아보는 연구가 필요할 것이다.