• 한국지반환경공학회 논문집
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• 제7권5호
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• pp.5-11
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• 2006

연약지반 설계시 영향을 미치는 주요 요인으로는 연약지반의 심도 및 지반의 특성값(압축지수, 압밀계수)을 결정하는 것이다. 이것은 연약지반의 설계시 지반의 침하거동을 예측할 수 있는 기초 자료가 된다. 신뢰성이 높은 지반조사 장비로 연약층의 심도를 결정하였더라도, 연약지반의 역학적 특성을 찾기 위한 실내시험 조건이 실제 지반환경을 완벽하게 재현하지 못하기 때문에 정확한 지반 특성값을 결정하는 것은 상당히 어려운 것이 현실이다. 따라서, 본 연구에서는 가장 신뢰성 있는 지반 특성값을 재산정하기 위해 인천국제공항 2단계 여객계류장 부지조성시의 317일간의 현장 계측데이터를 역해석 기법을 이용하여 지반의 특성값을 재산정하였다.

• 한국디지털건축인테리어학회논문집
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• 제13권4호
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• pp.109-117
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• 2013

The purpose of this study is to present our elderly welfare policy and welfare facilities for the elderly and to propose the future direction of policy for the elderly with comparison to that of Japan. The comparative study results of Korea and Japan are as follows: As the basis of elderly welfare, care insurance for the elderly is now fixated in the two countries. On the other hand, for quantitative expansion in Korea, the quality level has been gone down. Due to qualitative evaluation, the growth of facilities has slowed and material welfare providers was also a decline in the number of operators. Two countries in the field of community welfare in recent years has been actively promoting. It is the most important to solve the social welfare problem with local councils who know the area, which is a part of the future to focus and to support. Due to huge construction investment of facility, there is the burden of operators. This facility is appropriate for an extension of the home. However, it is in the hard economic times. Until now, the number of people in a room is at least four according to the legal standard of Korea, there are a few private rooms. On the other hand, in Japan, unit-care was phased since 2002 and private rooms have been expanded. In Japan, health center for the elderly plays an important role with special elderly nursing home among facilities for the elderly. Health center provides services that are recovering, nursing, and caring to support independence for the elderly after acute phase of treatment. As treatment and care, the aim of health center is to return the elderly to home. On the other hand, there are a few health centers for returning the elderly to home in Korea. Furthermore, in Japan, a project for preventive care has been begun. The project is needed in Korea.

• Computers and Concrete
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• 제22권1호
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• pp.53-62
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• 2018

Cracking of concrete cover induced by reinforcement corrosion is a critical issue for life-cycle design and maintenance of reinforced concrete structures. However, the critical degree of corrosion, based on when the concrete surface cracks, is usually hard to predict accurately due to the heterogeneity inherent in concrete. To investigate the influence of concrete heterogeneity, a modified rigid-body-spring model, which could generate concrete sections with randomly distributed coarse aggregates, has been developed to study the corrosion-induced cracking process of the concrete cover and the corresponding critical degree of corrosion. In this model, concrete is assumed to be a three-phase composite composed of coarse aggregate, mortar and an interfacial transition zone (ITZ), and the uniform corrosion of a steel bar is simulated by applying uniform radial displacement. Once the relationship between radial displacement and degree of corrosion is derived, the critical degree of corrosion can be obtained. The mesoscale model demonstrated its validity as it predicted the critical degree of corrosion and cracking patterns in good agreement with analytical solutions and experimental results. The model demonstrates how the random distribution of coarse aggregate results in a variation of critical degrees of corrosion, which follows a normal distribution. A parametric study was conducted, which indicates that both the mean and variation of critical degree of corrosion increased with the increase of concrete cover thickness, coarse aggregates volume fraction and decrease of coarse aggregate size. In addition, as tensile strength of concrete increased, the average critical degree of corrosion increased while its variation almost remained unchanged.

• 한국공간정보시스템학회 논문지
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• 제2권1호
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• pp.43-55
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• 2000

지리정보시스템은 다양한 학문 분야와 여러 전문 기술을 필요로 하는 복합적인 소프트웨어 시스템이므로 일반적인 시스템에 비하여 개발 과정의 복잡도가 높고, 개발된 시스템의 사용자 인터페이스나 수행 연산을 이후에 변경하기가 쉽지 않다. 그러므로 이미 개발된 지리정보시스템이 존재하여도 상이한 응용 분야에 사용될 목적으로 다른 지리정보시스템을 구축하고자 할 경우 이의 대부분을 재개발하여야 하는 경우가 많다. 즉, 이미 개발된 지리정보시스템에 대한 이후의 재사용이 용이하지 않다. 따라서 개발된 기존 지리정보시스템의 기능을 재사용할 수 있도록 하여 이를 바탕으로 다양한 응용 분야의 지리정보시스템을 용이하게 구축하고자 하는 연구의 필요성이 제기된다. 본 논문은 클라이언트 중심 웹 지리정보시스템의 구조를 기반으로 하여, 응용 웹 지리정보시스템의 구축을 용이하게 할 목적으로 웹 지리정보시스템 프레임워크를 설계하고 구현한다. 프레임워크는 클래스(class), 객체, 모듈 등과 같이 재사용 가능한 단위로 이루어진 소프트웨어 라이브러리를 의미한다. 제안하는 웹 지리정보시스템 프레임워크는 기본적인 웹 지리정보시스템의 기능과 수행 구조를 제공하여 웹 지리정보시스템 개발자로 하여금 응용 분야에 필요한 연산과 사용자 인터페이스만을 추가하여 다양한 응용 분야의 요구 조건을 만족하는 응용 웹 지리정보시스템을 용이하게 구축할 수 있도록 한다. 이는 또한 웹 브라우저가 지원하는 기존의 개발 환경을 통하여 이루어지므로 기존의 웹 어플리케이션 개발 도구를 그대로 사용할 수 있다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제29권3호
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• pp.262-267
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• 2007

Implantation of allografts has increased widely with not only the availability of many allogenic bone but also allogenic soft tissues. The aim of tissue banking is to provide surgeons with safe tissues compatible with their intended clinical application. The incidence of tissue transplant-transmitted infection is unknown and can only be inferred from prospective studies. The possibility of donor-to-recipient disease transmission through soft tissue transplantation can be considered by reviewing the risk associated with other transplanted hard tissues. Viral, bacterial, and fungal infections have been transmitted via transplantation of soft tissue allografts such as skin, cornea, dura, pericardium. fascia lata, and heart valves. Corneas have transmitted rabies, Creutzfeldt-Jakob disease (CJD), hepatitis B (HBV), cytomegalovirus (CMV), herpes simplex virus (HSV), bacteria, and fungi. Heart valves have been implicated in transmitting tuberculosis, hepatitis B. HIV-1 and CMV. CJD has been transmitted by dura and pericardium transplants. Skin has transmitted CMV, bacteria, and fungi. Cadaveric skin, pericardium, dura, and fascia lata have been used in dental patients with intra-oral soft tissue injuries and GBR. This study is review of the considering transmission of infectious disease in allogenic soft tissues and guidelines of reducing the risk. Prior to use, many tissues are exposed to antibiotics, disinfectants, and sterilants, which further reduce or remove the risk of transmitted disease. Because some soft tissue grafts cannot be subjected to sterilization steps, the risk of infectious disease transmission remains and thorough donor screening and testing is especially important.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제37권5호
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• pp.380-385
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• 2011

Introduction: Hydroxyapatite ($Ca_{10}(PO_4)_6(OH)_2$, HA) is the main inorganic phase of human hard tissue that is used widely as the repair material for bones. When HA is applied to a bony defect, however, it can be encapsulated with fibrous tissue and float in the implanted area due to a lack of consolidation. Bioceramics as allogenic graft materials are added to HA to improve the rate and bone healing capacity. Fluoridated hydroxyapatite ($Ca_{10}(PO_4)_6(OH,F)_2$, FHA), where F- partially replaces the OH- in hydroxyapatite, is considered a good alternative material for bone repair owing to its solubility and biocompatibility. Materials and Methods: This study was designed to determine the bone healing capacity of FHA newly produced as a nanoscale fiber in the laboratory. HA and FHA with bioglass was implanted in a rabbit cranium defect and the specimen was analysed histologically. Results: 1. At 4 weeks, fibrous connective tissue and little bone formation was observed around the materials of the experimental group I implanted HA and bioglass. Newly formed bone was observed around the materials in the experimental group II implanted FHA and bioglass. 2. At 8 weeks, the amount of newly formed and matured bone was higher in experimental group II than in experimental group I and the control group. Conclusion: These results suggest that FHA and bioglass is a relatively favorable bone substitute with biocompatibility and better bone healing capacity than pure HA and bioglass.

• Journal of Advanced Marine Engineering and Technology
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• 제39권8호
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• pp.843-848
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• 2015

The objective of this study is to observe and optimize a typical ocean environment and reduce wave reflections in the wave flume. In order to generate ocean waves in the wave flume, a combination of a horizontal piston type wave generator and wave absorbers was installed in the channel. Two probes for measuring the wave heights, i.e., wave level gauges, were used to record the continuous variation of the wave surface, the phase difference, and the maximum (crest) and minimum (trough) points of the propagating waves. In order to optimize the shape and size of the propagating waves, several absorption methods were proposed. Apart from an active wave absorption method, we used methods that involved vertical porous plates, horizontal punching plates, and sloping-wall-type wave absorbers. To obtain the best propagating waves, a sloping-wall-type wave absorber was chosen and tested in terms of the constitutive filling materials and the location and shape of the plate. This study also focused on the theoretical prediction of the wave surface, separating them into the incident and reflective components. From the results, it is evident that the wave absorber comprising a hard filling material exhibits a better performance than the absorber comprising a soft material, i.e., the wave absorber can be a strong sink to control the energy of the incoming wave. In addition, larger wave absorbers correspond to lower reflectance because a larger volume can reduce the incoming wave energy. Therefore, at constant absorber conditions, the reflectance of the wave increases as the wave period increases. Finally, the reflectance of the wave was controlled to be less than 0.1 in this study so that the wave flume can be used to simulate an offshore environment.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.79-79
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• 2017

Metallic biomaterials have been mainly used for the fabrication of medical devices for the replacement of hard tissue such as artificial hip joints, bone plates, and dental implants. Because they are very reliable on the viewpoint of mechanical performance. This trend is expected to continue. Especially, Ti and Ti alloys are bioinert. So, they do not chemically bond to the bone, whereas they physically bond with bone tissue. For their poor surface biocompatibility, the surface of Ti alloys has to be modified to improve the surface osteoinductivity. Recently, ceramic-like coatings on titanium, produced by plasma electrolytic oxidation (PEO), have been developed with calciumand phosphorus-enriched surfaces. A lso included the influences of coatings, which can accelerate healing and cell integration, as well as improve tribological properties. However, the adhesions of these coatings to the Ti surface need to be improved for clinical use. Particularly Silicon (Si) has been found to be essential for normal bone, cartilage growth and development. This hydroxyapatite, modified with the inclusion of small concentrations of silicon has been demonstrating to improve the osteoblast proliferation and the bone extracellular matrix production. Strontium-containing hydroxyapatite (Sr-HA) was designed as a filling material to improve the biocompatibility of bone cement. In vitro, the presence of strontium in the coating enhances osteoblast activity and differentiation, whereas it inhibits osteoclast production and proliferation. The objective of this work was to study Morphology of bone-like apatite formation on Sr and Si-doped hydroxyapatite surface of Ti-6Al-4V alloy after plasma electrolytic oxidation. Anodized alloys was prepared at 270V~300V voltages with various concentrations of Si and Sr ions. Bone-like apatite formation was carried out in SBF solution. The morphology of PEO, phase and composition of oxide surface of Ti-6Al-4V alloys were examined by FE-SEM, EDS, and XRD.

• 한국주조공학회지
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• 제13권1호
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• pp.62-70
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• 1993

This study presents the effect of applied pressure on the preform deformation during squeeze casting of $Al_2O_3$ short fiber reinforced aluminum alloy (AC8A) metal matrix composites. A preliminary model based on the general beam theory is suggested for the prediction of the preform deformation. Two different commercially available $Al_2O_3$ short fiber (Saffil, Kaowool) were used to study the influence of the fibers on the microstructure and mechanical properties of the squeeze cast $Al/Al_2O_3$ composites. The composites were fabricated with the applied pressure of 75 MPa which was found to be the optimum condition for the squeeze casting of the composites in this study. For the amorphous Kaowool fiber, hard crystalline Mullite phase was formed with heat treatment. Both of amorphous and the crystallized Kaowool fibers were used to fabricate $Al/Al_2O_3$ composites. Microhardness of crystallized Kaowool fiber revealed higher than that of the amorphous Kaowool fiber in the squeeze cast composites. It was also found that the wear resistance of Kaowool fiber reinforced composites increased with the amount of Mullite.

• 열처리공학회지
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• 제17권6호
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• pp.346-355
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• 2004

The flame quenching process has been employed to modify the surfaces of commercial marine propeller material, aluminum bronze alloy (Cu-8.8Al-5Ni-5Fe), and the microstructure, hardness and wear properties of the flame-quenched layers have been studied. The thermal history was accurately monitored during the process with respect to both the designed maximum surface temperature and holding time. The XRD and EDX analyses have shown that at temperatures above $T_{\beta}$, the microstructure consisting of ${\alpha}+{\kappa}$ phases changed into the ${\alpha}+{\beta}^{\prime}$ martensite due to an eutectoid reaction of ${\alpha}+{\kappa}{\rightarrow}{\beta}$ and a martensitic transformation of ${\beta}{\rightarrow}{\beta}^{\prime}$. The ${\beta}^{\prime}$ martensite phase formed showed a face-centered cubic (FCC) crystal structure with the typical twinned structure. The hardness of the flame-quenched layer having the ${\alpha}+{\beta}^{\prime}$ structure was similar to that of the ${\alpha}+{\kappa}$ structure and depended sensitively on the size and distribution of hard ${\kappa}$ and ${\beta}^{\prime}$ phases with depth from the surface. As a result of the sliding wear test, the wear resistance of the flame-quenched layer was markedly enhanced with the formation of the ${\beta}^{\prime}$ martensite.