• 가족자원경영과 정책
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• 제19권1호
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• pp.139-161
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• 2015

The number of Healthy Family Support Centers has increased and the services for enhancement of family strength have extended during the past ten years since the Framework Act on Healthy Families was enacted. It is time to pay attention to the empowerment for Healthy Family Specialist because their capability is directly linked to improve the quality of services, which means the satisfaction of family services and the quality of family policy. In this context, this study investigate organizational experience of Healthy Family Specialists and suggest the empowerment plan to enhance their capability. We conducted in-depth interviews for 9 Healthy Family Specialists who is currently working at Healthy Family Support Centers as a manager status during June 2014. We analyzed organizational experiences through job commitment and job satisfaction and empowerment plans through their strength and weakness. Our findings revealed that job commitment and job satisfaction of Healthy Family Specialist are relatively low due to a poor working condition and a low brand awareness. Also, the capability of Healthy Family Specialists is an important factor to determine their job commitment and job satisfaction, and it can impact on the long service. These results suggest that the payroll system, increment of salary, career recognition, employee benefit, systematic operation, and motivation are needed to improve their job satisfaction. There are various ways to improve professional capability of Healthy Family Specialists besides education program. This study contributes to make the plan of empowerment for Healthy Family Specialists and it also contributes to improve the service quality of family policy.

• 한국지반공학회지:지반
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• 제13권4호
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• pp.177-198
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• 1997

화강토는 일반 퇴적토와는 달리 풍화도, 입자파쇄성등 시료의 초기상태에 따라 전단거동을 달리하는 특성을 가지므로 각 경우에 대한 응력-변형률 관계를 밝히고 전단강도의 변화특성을 조사할 필요가 있다. 이와같은 관점에서 본 연구에서는 모암조성성분 및 풍화도를 달리하는 4개지역의 화강토를 채취하여 불교란 및 교란(정적다짐)상태에서 직접전단시험과 삼축압축시험(CU, CD)을 수행하였다. 이 결과 불교란화강토의 응력-변형률거동은 구속압이 작을때는 과압밀점토의 응력경로거동처럼 경화에서 연화거동을, 교란화강토는 풍화도에 관계없이 퇴적점토와 같은 경화-일정거동을 나타내었다. 또한, 통상적인 직접전단시험에서 얻는 점착력은 특히, 불교란화강 토에서 과대평가 되는 경향이 있으며 삼축압축시험에서의 응력비(q/p')와 체적변형률증뚠비 (dv/de)의 관계는 함수비, 풍화도, 구속압력, 교란에 관계없이 하나의 식($dv/d\varepsilon,=\alpha(M-\eta))$으로 근사화시킬 수 있었다.

• 대한치과보철학회지
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• 제38권6호
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• pp.782-790
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• 2000

The mainly used polymeric material for the denture is PMMA because of its cost and easiness to handle. So it was widely used material among dentists for past decades. But the acrylic-based denture materials have several common weak points such as shrinkage after curing and lack of strength. In order to solve these problems, we adapted one of hybrid system using acrylic polymer and vinyloligosilsesquioxane(POSS). POSS, which is a well known expandable monomer during polymerization process, may eventually suppress volumetric shrinkage. And the hybrid system makes it possible for the polymer to be stable in various severe conditions. Eight different kinds of samples were designed and synthesized. Each samples were characterized with dynamic mechanical analyser(DMA) to confirm their thermodynamic properties, fractured to analyze the cross-sectional morphology of the samples. And elongation, flexural and impact tests were also executed to evaluate the mechanical properties of the samples. From the results, hybrid composites had well defined crosslinked network structure compared to the widely used denture materials, and the mechanical strength improved without changing any surface condition as increment with POSS ratio in hybrid system. Fractured morphology showed homogeneous surfaces in spite of mutli component system, therefore we can conclude that the adoption of the POSS brought the reinforcement of the denture resin.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.889-892
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• 2008

본 연구는 보통포틀랜드 시멘트(이하 OPC)의 제조공정 중 입도 분급에 의해 포집된 조분시멘트(이하 CC)와 저발열 혼화재료인 플라이애시(이하 FA)를 조합 치환하여 콘크리트에 미치는 수화발열특성에 대해 검토하고자 하였다. 실험은 W/B 50% 1수준에 대하여 OPC를 100% 사용한 것을 Plain 배합으로 하고, CC를 OPC에 대하여 25, 50, 75%의 3수준으로 치환하고, 혼화재로 FA를 0, 10, 20, 30, 40%의 5수준으로 치환하여 총 16배치를 계획 하였다. 실험결과로 유동성의 경우는 CC 치환율이 증가할수록 점점 감소하는 경향을 나타냈고, FA의 치환율이 증가할수록 증가하였다. CC 및 FA 치환율 별간이단열에 의한 온도 상승량은 치환율이 증가할수록 감소하였는데, 특히 FA40의 경우 CC치환율에 관계없이 최대 피크온도가 $7.3{\sim}8.9^{\circ}C$로 45%정도 아주 낮게 나타났다. 초기 압축강도는 CC 및 FA치환율 증가에 따라 비례적으로 저하하였는데, 재령경과에 따라 강도저하 폭은 감소하는 것으로 나타났다.

• 한국지반공학회논문집
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• 제33권2호
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• pp.27-34
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• 2017

국내 건설 현장에서는 다양한 흙막이 공법이 적용되고 있으며 깊은 지하굴착에는 연속주열식공법(C.I.P)이 많이 적용되고 있다. 그러나 여러 단점들이 있어 이를 보완하기 위하여 PHC 말뚝을 이용한 흙막이 공법이 개발되었다. PHC 말뚝을 이용한 흙막이 공법은 품질이 균질하고 강성이 우수하여 안정성의 확보에 유리한 장점이 있다. PHC-W 말뚝은 PHC 말뚝의 단면을 변경한 제품으로, 수평 토압에 저항하기 위한 최적 설계를 통해 제작되었다. 그리고 KS F 4306 시험을 통하여 휨 모멘트 및 전단강도의 증가효과를 검증하였으며 휨 모멘트와 전단강도는 KS 기준보다 약 42%, 98% 증가되었다.

• 한국재료학회지
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• 제28권12호
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• pp.702-708
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• 2018

This study deals with the effect of microstructure factors on the strain aging properties of API X70 pipeline steels with different microstructure fractions and grain sizes. The grain size and microstructure fraction of the API pipeline steels are analyzed by optical and scanning electron microscopy and electron backscatter diffraction analysis. Tensile tests before and after 1 % pre-strain and thermal aging treatment are conducted to simulate pipe forming and coating processes. All the steels are composed mostly of polygonal ferrite, acicular ferrite, granular bainite, and bainitic ferrite. After 1 % pre-strain and thermal aging treatment, the tensile test results reveal that yield strength, tensile strength and yield ratio increase, while uniform elongation decreases with an increasing thermal aging temperature. The increment of yield and tensile strengths are affected by the fraction of bainitic ferrite with high dislocation density because the mobility of dislocations is inhibited by interaction between interstitial atoms and dislocations in bainitic ferrite. On the other hand, the variation of yield ratio and uniform elongation is the smallest in the steel with the largest grain size because of the decrease in the grain boundary area for dislocation pile-ups and the presence of many dislocations inside large grains after 1 % pre-strain.

• Metals and materials international
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• 제24권6호
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• pp.1376-1385
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• 2018

Ultrasonic melt treatment (UST) was applied to an A390 hypereutectic Al-Si alloy in a temperature range of $750-800^{\circ}C$ and its influence on the solidification structure and the consequent increase in strength was investigated. UST at such a high temperature, which is about $100^{\circ}C$ above the liquidus temperature, had little effect on the grain refinement but enhanced the homogeneity of the microstructure with the uniform distribution of constituent phases (e.g. primary Si, ${\alpha}-Al$ and intermetallics) significantly refined. With the microstructural homogeneity, quantitative analysis confirmed that UST was found to suppress the formation of Cu-bearing phases, i.e., $Q-Al_5Cu_2Mg_8Si_6$, $Al_2Cu$ phases that form in the final stage of solidification while notably increasing the average Cu contents in the matrix from 1.29 to 2.06 wt%. A tensile test exhibits an increase in the yield strength of the as-cast alloy from 185 to 208 MPa, which is mainly associated with the solute increment within the matrix. The important role of UST in the microstructure evolution during solidification is discussed and the mechanism covering the microstructure-strengthening interrelationship of the ultrasonically treated A390 alloy is proposed.

• Structural Engineering and Mechanics
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• 제69권1호
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• pp.11-20
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• 2019

The biaxial failure mechanism of transversally bedding concrete layers was numerically simulated using a sophisticated two-dimensional discrete element method (DEM) implemented in the particle flow code (PFC2D). This numerical modelling code was first calibrated by uniaxial compression and Brazilian testing results to ensure the conformity of the simulated numerical model's response. Secondly, 21 rectangular models with dimension of $54mm{\times}108mm$ were built. Each model contains two transversely bedding layers. The first bedding layer has low mechanical properties, less than mechanical properties of intact material, and second bedding layer has high mechanical properties, more than mechanical properties of intact material. The angle of first bedding layer, with weak mechanical properties, related to loading direction was $0^{\circ}$, $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $75^{\circ}$ and $90^{\circ}$ while the angle of second layer, with high mechanical properties, related to loading direction was $90^{\circ}$, $105^{\circ}$, $120^{\circ}$, $135^{\circ}$, $150^{\circ}$, $160^{\circ}$ and $180^{\circ}$. Is to be note that the angle between bedding layer was $90^{\circ}$ in all bedding configurations. Also, three different pairs of the thickness were chosen in models, i.e., 5 mm/10 mm, 10 mm/10 mm and 20 mm/10 mm. The result shows that in all configurations, shear cracks develop between the weaker bedding layers. Shear cracks angel related to normal load change from $0^{\circ}$ to $90^{\circ}$ with increment of $15^{\circ}$. Numbers of shear cracks are constant by increasing the bedding thickness. It's to be noted that in some configuration, tensile cracks develop through the intact area of material model. There is not any failure in direction of bedding plane interface with higher strength.

• Computers and Concrete
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• 제23권6호
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• pp.433-444
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• 2019

As rice husk ash (RHA) is not produced in controlled manufacturing process like cement, its properties vary significantly even within the same lot. In fact, properties of Rice Husk Ash Based Concrete (RHABC) are largely dictated by uncertainty leading to huge deviations from their expected values. This paper proposes a Robust Cost Optimization (RCO) procedure for RHABC, which minimizes such unwanted deviation due to uncertainty and provides guarantee of achieving desired strength and workability with least possible cost. The RCO simultaneously minimizes cost of RHABC production and its deviation considering feasibility of attaining desired strength and workability in presence of uncertainty. RHA related properties have been modeled as uncertain-but-bounded type as associated probability density function is not available. Metamodeling technique is adopted in this work for generating explicit expressions of constraint functions required for formulation of RCO. In doing so, the Moving Least Squares Method is explored in place of conventional Least Square Method (LSM) to ensure accuracy of the RCO. The efficiency by the proposed MLSM based RCO is validated by experimental studies. The error by the LSM and accuracy by the MLSM predictions are clearly envisaged from the test results. The experimental results show good agreement with the proposed MLSM based RCO predicted mix properties. The present RCO procedure yields RHABC mixes which is almost insensitive to uncertainty (i.e., robust solution) with nominal deviation from experimental mean values. At the same time, desired reliability of satisfying the constraints is achieved with marginal increment in cost.

• 한국터널지하공간학회 논문집
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• 제12권2호
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• pp.105-116
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• 2010

지표면 침하량, 지반거동 그리고 터널변위에 대한 평가는 미고결 저토피 도심지터널의 설계에서 주요한 인자가 된다. 이와 같은 터널에서 굴착에 따른 변형 해석은 터널 측벽부에서 지표부까지 발달하는 전단대의 변형특성을 파악하는 것이 중요하다. 본 연구는 소성항복이 시작된 후 최대 전단변형률증분과 함께 전단 탄성계수과 강도 정수의 저하를 고려할 수 있는 비선형 모델방법을 통하여 터널 변형거동에 끼치는 주요 설계인자의 효과에 대해 수치해석적 매개변수를 통해 분석하였다. 수치해석적 매개변수에 있어서 강도정수의 감소와 전단변형률의 증분, 초기지중응력, 점착력 그리고 숏크리트의 두께를 고려하여 수행하였다.