• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.7
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• pp.565-572
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• 2021

In this study, a study on the performance and aging of explosive bolts stored for a long time among pyrotechnic mechanical devices(PMD) used as separation devices in the defense field is conducted. For this, explosive bolts that had been installed in the weapon system for about 10 years are secured. Performance and life extension test procedures are established based on the AIAA Standard and MIL-STD. Before performance evaluation, non-functional tests are performed to check whether external changes or failures occurred. Next, circuit inspection and X-ray tests are conducted to check the failure in internal circuits and structures. After that, performance test is carried out to confirm the operation of the samples that passed the non-functional test. Through this test, separation of bolt and separation time are measured, and some samples are tested after a high temperature storage test to confirm the remaining life and the possibility of extension. Finally, the remaining life and reliability are predicted based on the results of the test and the Arrhenius model to identify remaining shelf life and reliability depend on time.

• Journal of Oral Medicine and Pain
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• v.32 no.4
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• pp.383-396
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• 2007

The aim of this study was to measure the suprathreshold taste intensity for NaCl, sucrose, citric acid, and quinine HCl in elderly Korean women using a whole-mouth, sip-and-spit procedure, employing the method of magnitude matching. The results were analysed in terms of aging, menopause, and salivary flow rate. 31 elderly women (mean age; $50.8{\pm}5.1$ years) and 30 young women (mean age; $25.1{\pm}1.71$ years) were included for the study. Subjects were instructed to give nonmodulus magnitude estimates to the intensities of five concentrations each of sucrose, NaCl, citric acid, and quinine HCl; distilled water; 6 loudness level of a 1,000-Hz tone, using the same 9-point intensity scale. Each of the 21 taste stimuli and 6 auditory stimuli are presented in random order twice. The auditory function is used to assess the absolute intensity function of the subject's taste system. The results were as follows; 1. Comparing to young women, elderly women showed decreased taste intensities for lower concentration solutions of NaCl and sucrose. However, other solutions didn't show any difference in taste intensities between young and elderly women. 2. There were not significant difference in perceived taste intensities for NaCl, sucrose, citric acid, and quinine HCl between menopause and pre-menopause women in elderly women group. 3. There were not significant difference in perceived taste intensities for NaCl, sucrose, and quinine HCl between low salivation women and high salivation women in elderly women group. 4. The low salivation women in elderly group showed higher taste intensity for low concentration citric acid than high salivation women.

• Journal of the Korean Applied Science and Technology
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• v.31 no.1
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• pp.120-129
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• 2014

The structure and physiological function of human skin continuously weaken due to growing older. The reasons of aging from external conditions are long term exposure to sun, wind, heat, cigarette smoke, and etc. This also palmitoyl oligopeptide or ceramide oligopeptide are known asc ingredient stimulating collagens and have the effect of reproducing the upper level of skin. Acetyl hexapeptide is an ingredient that makes the skin and muscle suppler and reduces wrinkles. It is a major high function beauty ingredient that substitutes botox. After dividing 7%, 14%, and 20% Acetyl hexapeptide experimental groups as groups A, B, and C the control group and experiment groups' change of wrinkles, hair follicles, moisture content, and dead skin cells was analyzed. According to the results, Acetyl hexapeptide seems to affect wrinkles, hair follicles and moisture content contrasting to the control group. Experimental groups and control group showed similar change in dead skin cells. In contrast to the control group satisfaction of examines was affected in wrinkles, hair follicles and moisture but removing dead skin cells had similar result in experimental groups and control group.

• Journal of Radiation Protection and Research
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• v.20 no.3
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• pp.181-186
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• 1995

UV irradiation causes a variety of biologic effects on the skin. These effects can be devided to acute reactuons and chronic reacxtions by duration of UV irradiation. Acute reactions are erythema reaction, pigment reactions and changes in epidermal thickness. Among them erythema reaction is most common and conspicuous acute effects of the skin. Upon exposure to sun or artificial UV soures, a faint redness response of skin may begin. Larger exposure causes sunburn reaction which is exaggerated erythema reactionassociated with pain, swelling, vesicle and dulla. Extent and time course of erythema reaction depend upon several factors including wavelength and dose of UVR, skin conditions likeas skin type, site, color, temperature, humidity and environmental factors. Evaluation of erythema erythema induced by UV irradiation is difficult to quantify. Degree of redness of skin are usually estimated by subjective visual evaluation. The lowest exposure dose required to protuce erythema is called minimal erythema dose (mod). Repeated exposures of UVR result in photaging skin. In this condition we can see wrinkling, skin atrophy, dilated blood vessels and keratoses. In sensitive persons photocarcinogenesis is can Be developed on exposed area of skin. Recently skin canser is increasing now in our country. An effective public education and photopreventive method must be developed.

• International Journal of Highway Engineering
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• v.8 no.4 s.30
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• pp.135-143
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• 2006

This study evaluated the fatigue resistance characteristics of hot-mix recycled asphalt mixtures which were prepared by a new blending method. Since the binder of RAP shows higher viscosity without being rejuvenated in the ordinary recycled mixture, this new(modified) blending method was developed for obtaining more uniform level of binder viscosity in the recycled mixture. Cold-planned RAP was collected and mix design was performed using 15% RAP content for two virgin aggregate, gneiss and granite. Penetration grade of 60-80 asphalt was used in mixing recycled mixture together with a polymer modifier, LDPE. Indirect tensile fatigue tests were carried out to evaluate characteristics of fatigue resistance of performance of recycled asphalt mixtures. The recycled mixtures with LDPE 6% showed higher repeated loading fatigue life. Fatigue life ratio of new(N) mixing method mixtures was approximately 0.6-0.7 before aging and 0.8-1.0 after aging treatment of ordinary(O) mixing method mixture. This means the N mixture becomes stronger with aging process increase. If further aging is treated, N mixture may be showing stronger resistance than O mixture.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.421-421
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• 2012

Cu(In,Ga)$Se_2$ (CIGS) 화합물은 직접천이형 반도체로 열적으로 매우 안정하고 에너지밴드갭이 1.04 eV로 이상적인 값에 가깝고, 특히 높은 광흡수계수를 가지기 때문에 박막 태양전지로서 커다란 응용 잠재력을 갖고 있는 광흡수층 재료이다. CIGS 화합물 박막 태양전지의 효율은 연구실에서는 ~20%를 높은 효율을 보고하고 있으며, 모듈급에서도 ~13%의 효율을 보이고 있다. 그러나 CIGS 박막 태양전지를 대면적 또는 양산화에 적용하기 위해서는 20년 이상의 장기적인 수명을 보장할 수 있는 내구성을 갖추어야 한다. 본 연구에서는 CIGS 모듈의 장기적인 신뢰성을 평가하기 위해 CIGS PV 모듈을 대상으로 대표적인 고온 고습 조건인 IEC-61646 규격을 이용하여 $85^{\circ}C$/85% RH에서 1000시간 동안 가속시험이 수행되었고, 고온 환경하에서 모듈의 성능 저하에 미치는 영향을 고찰하기 위해 모듈을 $85^{\circ}C$에서 1000시간 노출시켰다. 두 종류의 가속 스트레스시험 후에 모듈들의 외형적인 노화현상 및 전기적 열화 성능을 분석하였다. 또한 모듈의 효율저하의 원인을 규명하기 위해 모듈 구성 재료 중 충진재료로 사용하는 EVA sheet와 투명전극 AZO를 대상으로 고장분석을 수행하였다. AZO의 미세구조 관찰, 결정상 분석, XPS 분석 및 전기적 분석과 EVA sheet의 FT-IR 분석과 TG-DSC 분석들을 종합하여 CIGS PV 모듈의 성능저하의 원인을 규명하였다.

• Therapeutic Science for Rehabilitation
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• v.12 no.1
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• pp.65-78
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• 2023

Objective : The typical decline in function due to aging includes limitations in vision, hearing, cognitive function, and activities of daily living. Therefore, this study evaluated the mediating effect of cognitive function on the relationship between vision and hearing and activities of daily living. Methods : The participants in this study were 36,767 persons from the long-term care database on older adults provided by the National Health Insurance Sharing Service. The extracted variables were: (i) independent variables: visual and hearing; (ii) dependent variables: basic and instrumental daily living activities; and (iii) mediator variables: cognitive function. Regression analysis was performed evaluate the mediating effects of the extracted variables. Results : Cognitive function showed a mediating effect of 30% on the relationship between vision and basic daily life activities and 42% in the relationship with instrumental daily life activities. The mediating effect was 50% in the relationship between hearing and basic activities of daily living, and 53% in the relationship with instrumental activities of daily living. Conclusion : Prevention programs for functional decline due to aging are in progress in Korea. Based on the results of this study, establishing a prevention program would help promote successful aging.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.65-65
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• 2003

Serotonin(5-hydroxytriptamine, 5-HT)은 biogenic amlne류 신경전달물질로써, 다양한 생리조절활성을 갖고있다. 생식과 관련된 5-HT 기능으로 최근 사정 기능의 조절 가능성이 제시되었는데, 항우울제로 흔히 사용되는 selective serotonin reuptake inhibitor(SSRI) 계 약물을 장기 투여할 때 Premature ejaculation이 개선된다는 임상적인 증거들이 보고되었다. 본 연구는 수컷 흰쥐를 사용하여 생식기관, 특히 사정과 관계되는 기관들에서의 5-HT 수용체 아형들의 유전자 발현 여부와 그 조절 기작을 조사하였다. 흰쥐 수컷의 생식장기들인 고환, 부정소, 정관, 정낭에서 사정현상에 관여하리라 추정되는 세로토닌 수용체 아형들(type 1A, 1B, 2C)의 유전자 발현을 RT-PCR과 Southern blot으로 확인하였다. SSRI(sertraline)을 흰쥐에 매일 투여하는 모델(25mg/개체, 2주간)에서 1A 아형의 발현의 경우 정낭에서는 감소하였으나 정관에서는 증가하였고, 1B 아형의 발현은 두 장기에서 공히 증가하였다. 고환 제거후 testosterone(T) 보충 실험 모델을 사용한 실험에서, 정낭에서의 1A와 1B 발현은 T 보충에 의해 감소하였고, 정관에서는 큰 변화가 없었다. 한편 고환, 정낭과 정관에서의 세로토닌 수용체 아형 1A와 1B의 발현은 사춘기의 개시와 함께 증가하였다가 이후 점차 감소하는 경향을 보였다. 본 연구 결과는 사정 현상에 있어서 말초성 세로토닌 시스템이 중요한 역할을 담당할 가능성을 시사하는 것으로써, (i) 고등 포유동물에서의 사정 기작의 조절에 대한 과학적인 이해를 증진시키고, (ⅱ) 세로토닌 수용체 아형간의 특이한 발현과 작용에 대한 이해를 통해 보다 효과적인 사정 부전 치료법 개발을 시도할 수있고, (ⅲ) ontogeny와 sex steroid 의존성에 관련된 연구 시도는 노화와 관련된 사정능력의 변화와 같은 남성과학 분야로의 접목을 기할 수 있다고 사료된다.

• Journal of Korean Society of Steel Construction
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• v.19 no.1
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• pp.79-86
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• 2007

The corrosion durability of steel bridge coatings, such as organic and metallic coatings, is often evaluated by field exposure tests, but such tests take from several years to decades to complete. As a potential method for fast corrosion testing, accelerated exposure tests were considered in this study. The S6-cycle accelerated exposure test, specified in the Japanese Industrial Standards (JIS K5621), was carried out on uncoated structural steels for 30, 60, 90, 120 and 150 days, and the resultant weight loss was determined. The weight loss was compared with that obtained from previous field exposure tests, and acceleration factors of the S6-cycle test to field exposure test sites were determined. The application of the S6-cycle accelerated exposure tests to field environments was presented based on the acceleration factor and the amount of flying salt.

• The Korean Journal of Applied Statistics
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• v.35 no.4
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• pp.457-468
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• 2022

In aged society, it is important to prevent older people from being disability needing long-term care. The purpose of this study is to develop a prediction model to discover high-risk groups who are likely to be beneficiaries of Long-Term Care Insurance. This study is a retrospective study using database of National Health Insurance Service (NHIS) collected in the past of the study subjects. The study subjects are 7,724,101, the population over 65 years of age registered for medical insurance. To develop the prediction model, we used logistic regression, decision tree, random forest, and multi-layer perceptron neural network. Finally, random forest was selected as the prediction model based on the performances of models obtained through internal and external validation. Random forest could predict about 90% of the older people in need of long-term care using DB without any information from the assessment of eligibility for long-term care. The findings might be useful in evidencebased health management for prevention services and can contribute to preemptively discovering those who need preventive services in older people.