• Composites Research
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• v.32 no.6
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• pp.382-387
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• 2019

A single frequency strain mode test, a stress relaxation mode test, and a creep test using RH-DMA were performed to investigate the effects of relative humidity and temperature on the viscous properties of PET film. The relative humidity was 10%, 30%, 50%, 70%, and 90%. The temperature was considered to be 30~95℃ for single frequency strain mode tests, 30℃ and 70℃ for stress relaxation mode test, and 5~95℃ for creep test. According to the results, higher relative humidity results in lower storage modulus and loss modulus, but the maximum value of the loss modulus is not significantly affected by changes in relative humidity and is almost constant. Relaxation modulus decreases rapidly at the beginning and becomes constant, and as the temperature increases, it is susceptible to changes in relative humidity. Strain recovery also increases rapidly at the beginning and is susceptible to changes in relative humidity as the temperature increases. In addition, as the temperature increases, the degree of increase in creep compliance increases, and as the temperature rises above the glass transfer temperature, the degree of increase becomes very large. The master curve determined by the time-temperature superposition provides the information to predict the long-term performance under operating conditions such as relative humidity and temperature.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.1
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• pp.117-123
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• 2011

Impression taking procedure is very important for support, retention and stability of denture, and it affects the success of denture in completely edentulous patients. Various materials and methods have been used for impression taking in complete denture, while dynamic impression method is more physiological and functional method than the others. We had satisfying results with fabrication and relining of dentures after taking impression in the most physiological condition with recovery of deformed soft tissue by dynamic impression method using Coe-comfort$^{(R)}$ (GC America, IL, USA), tissue conditioner, in edentulous patients in this case report.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.3
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• pp.319-324
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• 2017

Patients with maxillectomy defects predisposed to not only difficulty in deglutition, mastication, speech but also psychological depression from impaired facial esthetics that affect life quality. Obturator prostheses play a important role in restoring the lost form, function and the quality of life for patients with maxillectomy defects. This clinical report presents the simplified approach to predict the degree of adequate facial support by Artificial palate which reflected from a maxillary interim obturator during the stabilization period after maxillectomy.

• 한국도로학회지:도로
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• v.5 no.4 s.18
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• pp.36-46
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• 2003

포장구조체에서 요구되는 강도를 갖게 하는 구조 설계의 방법은 경험적 절차부터 반역학적 절차까지 발전되어 왔다. 재생 가열아스팔트혼합물이 기존의 가열아스팔트혼합물(HMA)과 비교하여 비슷하거나 때에 따라 더 좋은 성능을 가져오므로, AASHTO설계지침서에서는 본질적으로 재생(recycled) HMA 재료와 신생(virgin) HMA 재료간의 차이가 없다고 기술하고 있으며, 기존 HMA 재료에 사용되는 덧씌우기설계법의 구조회복 분석방법(structural rehabilitation analysis method)을 재생포장설계에도 권장하고 있다. 재생 가열아스팔트의 설계를 위한 AASHTO 방법은 설계교통량, 교통량 및 수행능력예측의 신뢰수준, 공용기간, 그리고 포장상태 평가지수에 의하여 결정된 포장구조체에서 요구되는 포장두께지수(SN)에 기초한다. 포장두께지수(SN)는 포장층 두께, 상대강도계수, 각 층의 배수조건들의 곱의 조합으로서 나타내어질 수 있다. 덧씌우기로 간주될 수 있는 재생된 층의 포장두께지수(SN)는 기존 포장에서의 포장두께지수와 보강된 포장에서 요구되는 포장두께지수의 차이에 의하여 계산되어질 수 있다. 상대강도계수의 값은 AASHTO 설계지침에 명시되어 있다. AI 방법은 교통량, 노상의 회복탄성계수, 그리고 설계두께를 계산하기 위한 표층과 기층의 종류를 사용한다. 이 방법은 재생된 가열혼합물질과 기존의 가열혼합물질과는 거의 비슷한 성능을 나타낸다고 본다. 또다른 AI 방법에 의하면 재생된 층은 덧씌우기층이라고 간주하고, 현재의 포장두께와 요구되어지는 포장두께 사이의 차를 이용하여 재생될 층의 두께를 산정한다. 소요되는 덧씌우기 두께는 포장의 현장 상태지수(condition rating)와 각 종류에 따른 포장체와 포장재료가 아스팔트 콘크리트층의 등가두께로 전환되어 나타나는 방법에 근거하여 결정될 수 있다. 또 다른 방법은 포장체 각 층의 물성과 하중을 이용한 컴퓨터 프로그램에 의하여 산정된 하중-변형 응답에 의한 설계 방법을 포함한다. 이런 방법들에서는 포장체는 탄성이나 점탄성층 위에서 탄성이나 점탄성 거동을 보인다고 가정한다. 재생 상온혼합물에서의 AASHTO 설계 방법은 가열혼합물의 설계방법과 유사하다. 그러나, 재생 상온혼합물에서의 상대강도계수는 시공방법에 좌우되므로, 기술자의 판단을 근거로 하여 결정되어져야 한다. AI방법에서는 포장구조체를 다층탄성구조라고 보고, 노상의 강도와 설계 교통량을 근거로 요구되는 포장두께를 결정한다. 재생 상온혼합물 기층의 두께는 재생 상온혼합물 기충 위에서 가열아스팔혼합물에 대하여 산정된 덧씌우기 두께를 이용하여 결정할 수 있다. 아스팔트 표면의 재생은 기존 포장의 구조적 능력을 정상적으로 개선할 수 없으므로, 표면 재생의 두께를 설계하는 방법은 없다. 그러나, 임의의 덧씌우기 두께는 기존의 덧씌우기 설계법에 기초하여 산정 할 수 있다. 만약 덧씌우기가 승차감만을 개선시킨다고 여겨진다면, 혼합물에서 사용되어지는 최대 골재 크기에 기초한 최소 두께를 결정할 수 있다.

• Korean Journal of Social Welfare
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• v.63 no.2
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• pp.31-56
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• 2011

This study was done to identify experience of young adults street homeless aged 20-30s by knowing meaning and structure of empirical phenomena for procedure that how young adults became street homeless according to bio-psycho-social change. Five young adults street homeless were recruited who were on the air of SBS program, 'That why we want to know: young hope on the road-Young adults homeless are increased(Saturday July 26, 2008)', and from monthly magazine published by Homeless Center in Seoul. And phenomenological and heuristic Human Becoming Research Methodology of Parse was applied in this study. Although young adults street homeless made an opportunity for job, the working poor made him street homeless who suffer from social stigma and exclusion, but he struggled for self-support with social care. The quality of life for young adult street homeless depends on the social care under human rights with the bio-psycho-social aspects.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.280-289
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• 2013

Removable partial denture for oral function recovery of partial edentulous patients is a complicated treatment because the dentist should consider both hard tissue and soft tissue. Removable partial denture produced without consideration of precise design for each component and rotation of denture may cause fracture, deformation or loss of abutment teeth. In case of failure to achieve a proper denture, the reason of failure should be analyzed and the result must be applied to later RPD cases. Finding the solutions through the failed denture cases will help patients use their dentures more comfortably and keep their sound residual teeth and tissue longer.

• Journal of Life Science
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• v.17 no.5 s.85
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• pp.664-670
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• 2007

The propolis is natural product produced by honeybees and is known to have many biologically useful properties such as anti-microbial, anti-oxidative and anti-tumorigenic activity. However, its radio-protective property has not been well studied. To investigate radio-protective effect of propolis on mouse testis, mice were supplemented with propolis after 5 Gy irradiation. The histological changes of testis were detected by TEM. The results indicate that propolis may protect tissue deformation which is induced by 5 Gy of ionizing radiation. Furthermore, to elucidate the potential molecular mechanisms involved in radio-protective property of propolis, we performed microarray experiments using oligo DNA microarray. We found 65 up-regulated genes and 224 down-regulated genes, whose expression levels were affected more than 2-fold by propolis treatment in mice irradiated at 5 Gy. We confirmed microarray data with reverse transcription-PCR using gene specific primers. The results of RT-PCR are highly correlated with those of microarray. These results may help understanding molecular mechanisms of radioprotective effects by propolis in mouse model.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.238-244
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• 2019

Soft liner is used to functional impression technique when dental stone is immediately poured after taking impression because of viscoelasticity. In this case, a 78-year-old male visited for new dentures. Due to severe resorption of mandibular edentulous ridge, functional impression taking by closed mouth technique was planned. First of all, making maxillary and mandibular provisional dentures was done, and lined by soft liner to rehabilitate pressured maxillary and mandibular edentulous ridge. After this, Functional impression was taken by closed mouth technique using provisional dentures which are transformed to healed maxillary and mandibular edentulous ridge, and final denture were fabricated using maxillary provisional denture as a reference of artificial teeth arrangement. Consequently, restoring a complete edentulous patient with taking functional impression using provisional dentures resulted in recovering satisfying retention and function.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.3
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• pp.10-20
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• 2014

The purpose of this study is to define criteria for landscape restoration of palace gardens. The case study on Gyeongbokgung and Changdeokgung was used not only to evaluate effectiveness of the criteria, but also to propose solutions to issues of current restoration process of both palace gardens. Following three pairs of different concepts were chosen as criteria to determine on the original form: Diachrony vs. Synchrony, Originality vs. Contemporary Characteristics, and Invariance vs. Deformability. Gyeongbokgung has been restored based on its contemporary characteristics of Year 1888 and the main focus is on its architectural features rather than both architecture and landscape. However, in-depth complementary work on landscape restoration is necessary to restore its originality in Year 1395 such as analyzing photos of Gyeongbokgung taken in modern era. In case of Changdeokgung, we analyzed separately by region or landmark such as Jondeok-Pavilion(尊德亭), Yeonkyung-Hall(演慶堂), and Okryu-Stream(玉流川). Original form of Jondeok-Pavilion Area was changed in 1884. Since diachronic invariance that lasted for 240 years is more important criterion than its contemporary characteristics, it should be restored as how it was painted in Donggwoldo(東闕圖). In Yeonkyung-Hall Area, both original characteristics at the time of Hyomyung Crown Prince and contemporary characteristics of Emperor Kojong Era appear. Therefore, different solution is required for such area to be restored appropriately. Starting from era of King Injo(1636), diachrony and invariance of Okryu-Stream Area were continued throughout the era of King Sukjong and King Jeongjo(1800). It is more than 250 years before Okryu-Stream Area was altered under the rule of Emperor Kojong in 1884. In fact, alterations made to Okryu-Stream Area after 1884 doesn't hold much significance. Therefore, water landscape of Okryu-Stream Area, which was altered in the era of Emperor Kojong, needs to be restored based on Donggwoldo.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.121-128
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• 2005

Solder joints in microelectronic devices are frequently operated at an elevated temperature in service. They also experience plastic deformation caused by temperature excursion and difference in thermal expansion coefficients. Deformed solders can go through a recovery and recrystallization process at an elevated temperature, which would alter their microstructure and mechanical properties. In this study, to predict the changes in mechanical properties of Pb-free solder joints at high temperatures, the high temperature microhardness of several Pb-free and composite solders was measured as a function of temperature, deformation, and annealing condition. Solder alleys investigated include pure Sn, Sn-0.7Cu, Sn-3.5Ag, Sn-3.8Ag-0.7Cu, Sn-2.8Ag-7.0Cu (composite), and Sn-2.7Ag-4.9Cu-2.9Ni (composite). Numbers are all in wt.$\%$ unless specified otherwise. Solder pellets were cast at two cooling rates (0.4 and $7^{\circ}C$/s). The pellets were compressively deformed by $30\%$ and $50\%$ and annealed at $150^{\circ}C$ for 2 days. The microhardness was measured as a function of indentation temperature from 25 to $130^{\circ}C$. Their microstructure was also evaluated to correlate with the changes in microhardness.