• 한국해양공학회지
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• 제25권6호
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• pp.42-48
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• 2011

The present study makes three original contributions to nanoskinned Ti-6Al-4V materials. The nanoskins were fabricated on Ti-6Al-4V material using various surface treatments: deep rolling (DR), laser shot peening (LSP), and ultrasonic nanocrystal surface modification (UNSM). These surface treatments are newly developed techniques and are becoming more popular in industrial fields. A fatigue strength comparison at up to 106 cycles was conducted on these nanoskinned Ti-6Al-4V materials. Fatigue tests were carried out using MTS under axial loading tension-compression fatigue (R = -1, RT, 5 Hz, sinusoidal wave). The analysis of the crack initiation patterns in the nanoskinned Ti-6Al-4V materials found an interior originating crack pattern and surface originating crack type. Microscopic observation was mainly used to investigate the fatigue fractured sites. These surface modification techniques have been widely adopted, primarily because of the robust grade of their mechanical properties. These are mainly the result of the formation of a large-scale, deep, and useful compressive residual stress, the formation of nanocrystals by the severe plastic deformation (SPD) at the subsurface layer, and the increase in surface hardness.

• 한국항공우주학회지
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• 제36권1호
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• pp.62-71
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• 2008

액체로켓엔진에서 발생하는 고주파 연소불안정을제어하기 위하여 인젝터의 길이 변화를 줄 수 있는 다중 스월 인젝터의 감쇠효과를 분석하였다. 음향흡수자로서 인젝터의 효과를 분석하기 위하여 인젝터는 1/4 파장 공명기로 해석하였고, 상온에서 감쇠 효과의 적합성을 검증하였다. 인젝터 내부에 형성되는 air core의 부피가 감쇠 효과에 직접적인 영향을 주므로 이를 모사한 다수의 튜브로 실험을 하였다. 실험을 통해 각 모드의 배(anti-node point)에 장착된 인젝터의 수의 증가로 감쇠 효과가 커지는 것을 확인하였다. 또한 1L, 1T, 1L1T 모드에 동조된 인젝터들을 동시에 각 모드의 배에 장착했을 경우, 각 모드에서 단일 모드에 튜닝된 인젝터들을 장착하였을 경우와 거의 같은 감쇠 효과를 얻을 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제46권6호
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• pp.735-747
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• 2018

Radon radiation exposures in home have been posed as a potential cancer hazard. This research aims to present the basic data of the indoor radon concentration level by examining the radon exhalation rates of wood species. Radon exhalation rates from five commonly used wood species in Korean wood building construction were measured with Continuous Radon Monitor (CRM), Model 1028 (Sun Nuclear Co., USA) using the Closed Chamber Method (CCM). The mass exhalation rate was observed to vary from $0.00089Bq{\cdot}kg^{-1}{\cdot}h^{-1}$ to $0.00181Bq{\cdot}kg^{-1}{\cdot}h^{-1}$, whereas the surface exhalation rate was observed to be $0.00677-0.01517Bq{\cdot}m^{-2}{\cdot}h^{-1}$. The radon exhalation rate of Quercus accutissima Carruth (white oak) which has the highest density showed the highest figure among the five wood species, on the other hand, the rest of four species showed similar results which were similar to the radon exhalation rates of wood in the U.S.A. and Canada. The average of the concentration measured by the CCM represented well up to the second half-life period (7.7 days). Because result of these small quantities seems to indicate that radon exhalation from the tested wood species has almost negligible impact, the main culprit of the high indoor radon concentration is clearly derived from the background of surrounding wood house. Therefore, as a safety precaution, infrastructures made of wood materials should be designed with the consideration of influx of radon and built accordingly. Furthermore, it is highly desirable that wood will be needed to use for furniture and interior finishing material in indoor environment.

• Journal of Microbiology and Biotechnology
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• 제25권3호
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• pp.399-406
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• 2015

In this study, we developed a composite filler comprising cross-linked hyaluronic acid (HA) and human collagen (COL) derived from the human umbilical cord with the aim of improving its biocompatibility and longevity compared with commercially available fillers. After HA/COL composite fillers were made in two different ratios (10:1 and 5:1), the physical properties of the fillers were evaluated. The interior morphologies and in vivo weight change of these hydrogels were also characterized at 1-16 weeks after injection into mice. To evaluate their biocompatibility and durability in vivo, we injected the composite fillers into nude mice subcutaneously. The variations of injected gel weight were measured and compared with the commercial dermal fillers (Restylane and TheraFill). The composites showed improved or similar physical properties (complex viscosity of 19-22 × 10⁵ cP, and injection force of 10-12 N) over the commercial dermal fillers. Sixteen weeks following the injection, the ratio of remaining composite filler weight to initial weight (75.5 ± 16.9%; 10:1) was shown to be greater than that of the commercial fillers (43.2 ± 8.1%, Restylane; 12.3 ± 5.3%, TheraFill). In addition, immunohistochemical analysis with angiogenesis-related markers such as isolectin and vWF revealed newly formed blood vessels and cellular influx into the composite filler, which were not observed in the other fillers. These results clearly suggest that the HA/COL composite filler is a superior candidate for soft tissue reconstruction. The filler we developed may be a suitable candidate as an injectable dermal filler for tissue augmentation in humans.

• 약학회지
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• 제48권6호
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• pp.352-357
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• 2004

Atrial myocytes have two functionally separate groups of ryanodine receptors (RyRs): those at the periphery colocalized with L-type $Ca^{2+}$channels (DHPRS) and those a t the cell interior not associated with DHPRs. $Ca^{2+}$ current ($I_{ca}$) directly gates peripheral RyRs on action potential and the subsequent peripheral $Ca^{2+}$ release propagates into the center of atrial myocytes. The mechanisms that regulate the $Ca^{2+}$+ propagation wave remain Poorly understood. Using 2-D confocal$Ca^{2+}$ imaging, we examined the role of inositol 1,4,5-trisphosphate receptor (IP $_3R$) and mitochondria on ($I_{ca}$)- gated local $Ca^{2+}$ signaling in rat atrial myocytes. Blockade of IP $_3R$ by xestospongin C (XeC) partially suppressed the magnitudes of I ca-gated central and peripheral $Ca^{2+}$ releases with no effect on $I_{ca}$. Mitochondrial staining revealed that mitochondria were aligned with ${\thickapprox}2-{\mu}m$ separations in the entire cytoplasm of ventricular and atrial myocytes. Membrane depolarization induced rapid mitochondrial $Ca^{2+}$ rise and decay in the cell periphery with slower rise in the center, suggesting that mitochondria may immediately uptake cytosolic $Ca^{2+}$, released from the peripheral SR on depolarization, and re-release the $Ca^{2+}$ into the cytosol to activate neighboring central RyRs. Our data suggest that the activation of IP $_3R$ and mitochondrial $Ca^{2+}$ handing on action potential may serve as a cofactor for the $Ca^{2+}$ propagation from the DHPR-coupled RyRs to the DHPR-uncoupled RyRs with large gaps between them.

• 농촌지도와개발
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• 제22권3호
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• pp.345-354
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• 2015

In this study, the landscape characteristics and culture of the sacred Dangsan forests at Dongnae-ri, Seonae-ri, Namnae-ri, Pyeongchon-ri and Gyochon-ri were investigated. And the potential for registration in the World Heritage List has been discussed by linking the Dangsan forests at the five sites. Dangsan forest, a traditional village forests of rural Korea is a representative cultural heritage with a history of more than several hundred years of Dangsan ritual. The Dangsan forests in the neighborhood of Naganeuoseong have retained the landscape of town fortress during Choseon Dynasty and the Dangsan ritual as a living culture. The three villages inside Naganeuoseong have kept their Upper Dang, Middle Dang and Lower Dang. There were 21 old trees in total; Zelkova serrata (2), Celtis sinensis (7), Aphananthe aspera (5) trees, Carpinus tschonoskii (2) and Ginkgo biloba (3). The three Dangsan trees and an old Aphananthe aspera, known as to be planted by the Admiral Yi Sun-sin were recognized. The two villages located outside of village fortress also have kept their Dangsan ritual. It is important whether the sites possesses authenticity in order to be listed in the World Heritage. The Dangsan forests in the neighborhood of Naganeuoseong have been verified for the authenticity, which should be focused. The places need to be clarified for their landscape features formed as a Dangsan forest, and sustainable protection and management plans are to be devised.

• 한국주거학회논문집
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• 제20권5호
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• pp.31-39
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• 2009

The purpose of this study was to find out the residents' consciousness of the unit plan on condominium apartment and to contribute to develop a condominium apartment unit plan in Daejeon City. This research was performed by a questionnaire survey method, 464 data was collected from apartment residents lived in about $85\;m^2$ unit with 3 rooms and the apartments was limited to the complexes within 1-4 years of the length of building at Yuseong-gu and Seo-gu. By analyzing those data, findings are as follows: 1) Residents thought living room, kitchen and bathroom were importment space in a unit plan. They needed a storage function in an entrance and a intermediate room, and Anbang(mater bedroom) so did. 2) L-DK plan type was very popular and the type of front DK with L on the floor plan was preferred. This was unique results. 3) Sub-kitchen was needed for a refrigerator of Kimchi, the location of it was related to a main kitchen and a utility. the third room was needed for library, home office and storage space. 3) Bath-tub in An-bang and showe-booth in public bathroom was preferred. This was same to the popular trend of Korean condominium apartment. 4) The enlargment remodeling of balcony was showed livingroom balcony or personal bedrooms at the time of occupancy. They needed the balcony near a kitchen or an utility to equip a storage facility. Additionally, residents were preferred to their taste rather than a choice of interior concept package services.

• 콘크리트학회논문집
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• 제19권3호
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• pp.301-312
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• 2007

무량판 구조의 슬래브-기둥 접합부는 뚫림전단파괴에 취약하여 구조 성능을 향상시킬 필요가 있다. 본 연구에서는 새로운 슬래브-기둥 접합부 전단 보강 방법인 래티스 보강의 강도와 변형 능력을 평가하기 위한 실험 연구를 실시하였다. 주기 횡 하중을 받는 4개의 래티스 보강 접합부에 대한 실험을 실시하였으며, 비교를 위하여 전단 무보강 시험체, 스터드 레일, 전단 밴드, 스터럽 등 다양한 기존의 전단 보강 방법으로 보강된 실험체에 대하여 실험을 실시하였다. 실험 결과, 래티스 보강은 강도와 변형 능력면에서 모두 우수한 성능을 나타내었으며, 현행 기준의 예측 강도를 현저히 상회하는 강도를 나타내어 전단 보강에 매우 효율적인 보강 방법으로 평가되었다. 반면에 스터럽, 스터드 레일과 전단 밴드 실험체는 전단 무보강 실험체에 비하여 강도 증진 효과가 크지 않거나, 그 강도에 미치지 못하는 강도를 나타냈다.

• International Journal of Human Ecology
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• 제8권2호
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• pp.29-46
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• 2007

The purpose of this study was to analyze characteristics of the bedroom environment of nursing homes for the elderly in Korea. Field case research was performed using a structured checklist and measurements, from Oct. 28th to Dec. 2nd, 2006. Collected data were analyzed for cognitive efficiency, privacy, safety, supportiveness and amenity. Based on nursing homes for the elderly nationwide (Ministry of Health and Welfare, 2006), we choose 43 facilities in which Seoul and six megalopolis areas that had answered our questionnaire in 2006. We then narrowed the list to 14 facilities, balanced them in terms of regional population. The contents of investigation consisted of eight categories: that general characteristics of the bedrooms (including number of residents per room, using a bed or floor mat, the size and shape of the chamber, space for wheelchair turning, signage), door of bedroom (including door, doorknob, door sill/level difference), windows in the bedroom(including type of window, window sill height, window treatment, window safety device/shape, view/daylight), furniture (including personal furniture and lock), finishes (material, character and color of wall, floor, ceiling), lighting (including types of lighting, night lighting, switch), bathroom in the bedroom (including signage, door size/type, doorknob shape, height of the washbowl, size of toilet bowl, handrail, finishes), and other facilities (including outlet and handrails).

• 한국식품조리과학회지
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• 제20권5호
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• pp.423-435
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• 2004

The purposes of this study were to compare, through a factor analysis, the perceived level of importance of 4 categories of features relating to food service management between salespeople and clients, to establish an effective marketing strategy for successful contracting. To obtain data on the perceived level of importance level of the factors affecting foodservice management contracts, questionnaires were developed using the Delphi technique, which were modified by apilot test. The questionnaires consisted of 4 categories and 19 items on the factors affecting foodservice management contracts, with the importance level of these factors measured on a 5 point-Likert type scale. Between March 12 and April 13 2003, the self-administrative questionnaires were mailed to the 60 salespeople and 280 clients. A total of 50 clients (25%) and 48 salespeople(77%) responded to the questionnaires. As a result, forprivate contracts and in competitive biding, the differences of the perceived importance level between the salespeople and clients of the 3 categories (the appropriateness of foodservice operation plan, sales ability, the conditions and costs of the contract) were significant. For the 5 items relating to private contracts, Field trip, Menu Management Plan, Sanitation and Safety Management, Cost per meal and Food Cost per meal, both the salespeople and clients perceived high levels of importance for all these items. For competitive biding, both the salespeople and clients perceived high levels of importance for the 6 item the Foodservice operation supportive system, Field trip, Menu Management Plan, Renewal plans for interior and environment, Cost per meal and Food Cost per meal.