• 한국지반공학회논문집
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• 제20권7호
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• pp.183-196
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• 2004

모래다짐말뚝은 압밀침하촉진과 지지력향상을 도모할 수 있는 연약지반 개량공법으로 그 사용성이 증가하고 있다. 본 연구에서는 실내시험과 3-D 유한요소해석을 수행하여 $30-40\%$의 저치환율 모래다짐말뚝의 하중전이특성을 고찰해본다. 또한, 이러한 연구결과는 실험치와의 검증을 통하여 모래다짐말뚝 하중전이특성평가를 위한 간편법을 제시하는데 사용되었다.

• 한국직업건강간호학회지
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• 제29권4호
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• pp.306-315
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• 2020

Purpose: This study was conducted to identify the effects of caffeine intake by shift workers on sleep, considering various variable related to the sleep health of shift workers. Methods: A descriptive survey study was conducted with 128 employees who worked shifts. Respondents were surveyed on their of caffeine intake behavior, schedule type, quality of sleep, health promotion behavior, and occupational stress. Differences in their quality of sleep were assessed using the t-test and analysis of variance, while factors influencing the effect of caffeine intake on the quality of sleep were analyzed using hierarchical logistic regression. Results: The average Pittsburgh Sleep Index, Korean Version score of those surveyed was 7.3±3.25, indicating that their quality of sleep was low. On the other hand, their aveage daily intake of caffeine was 1.6±0.99 cups (1 cup =150 mL) and 116.4±77.58 mg/dL of caffeine. When the various variables that could have affected the quality of sleep were corrected, an increase in the amount of caffeine consumed was found to lead to a decrease in the quality of sleep (p=.015). Conclusion: Caffeine intake by shift workers has a significant bearing on their quality of sleep; therefore, such intake should be adjusted to improve their sleep health.

• 대한기계학회논문집A
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• 제32권1호
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• pp.70-76
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• 2008

Periodic cellular metals (PCMs) are actively being investigated because of their excellent specific strength and stiffness, and multi-functionality such as a heat disperse structure bearing external loading. The Kagome truss PCM has been proved that it has higher resistance to plastic buckling and lower anisotropy than other truss PCMs. In this paper, the out-of-plane compressive responses of the WBK specimens have been measured, theoretically predicted and numerically analyzed. Three specimens of two-layered WBK are fabricated and tested for measuring the responses. The peak stress of compressive behavior and effective elastic modulus are predicted based on the equilibrium equation and elastic energy conservation. Moreover, the structure of the specimen is modeled using the commercial mesh generation code, PATRAN and the finite element analysis for the model under the compression is carried out using the commercial FE code, ABAQUS. Finally, the obtained results are compared with each other to analyze the compressive characteristics of Wire-woven Bulk Kagome (WBK).

• 대한토목학회논문집
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• 제8권2호
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• pp.155-166
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• 1988

본 연구는 복합체의 단부영향을 고려한 등각균등질, 이방성의 모델개발과 이에따른 유한요소해석 프로그램 개발에 중점을 두었다. 복합체는 2차원의 수평층을 가지며 선형, 탄성, 작은변형에 제한을 두었다. 본 연구에서 개발된 등가 균등질의 이론은 복합체의 전반적인 거동을 포함시킴은 물론 층과 수직인 경계면과 그 부근에 형성되는 단부의 영향과 층의 경계면에 생기는 응력집중 현상을 나타낼 수 있게 하였다. 이론개발에 있어 1차변수는 $C_0$연속의 유한요소 근사치를 가지도록 하였으며 이를위해 최고 1차의 미분치가 변형에너지에 나타나도록 변수를 택하였다. 결과적으로 유한요소해석은 매우 간단하고 경제적이었으며 이들의 정당성과 정확도를 입증하기위하여 여러하중 조건하의 복합체를 풀이하였다.

• Archives of Reconstructive Microsurgery
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• 제3권1호
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• pp.54-63
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• 1994

Pulp and palm of the hand and heel of the sole are anatomically unique. Satisfactory reconstruction of these areas presents the plastic surgeon with many challenges and requires durable and sensible skin coverage, minimal donor morbidity and reliable operative procedure. We presents 7 clinical cases of sensate instep free flap transfer in this paper during the last 2 years. Three cases were soft tissue defects due to crushing and avulsion injury on the pulp of finger. 1 case was unstable scar and redundant flap after reconstruction of soft tissue dect of palm and 1 case was contracture of first web of hand. One case was a soft tissue defect due to avulsion injury on heel. Lastly, one case was chronic osteomyelitis with open wound on lateral malleolar area. Follow-up period ranged from 3 months to 2 years. Through the whole follow-up period, all flaps were viable and durable to persistant stress or weight bearing and were sensible enough to porotect the recocstructed area from injuries and maintain functions. In conclusions, the instep free flap should be considered as a valuable tool in reconstruction of hand and extremity requiring durability and sensation.

• Archives of Reconstructive Microsurgery
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• 제25권1호
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• pp.19-24
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• 2016

Urethral reconstruction is a problematic issue, thus its management can be challenging. Different methods using various materials were introduced for urethral reconstruction. The authors have made some changes in the groin flap surgery, affording more successful urethral reconstruction for defects of long urethra and penile soft tissue. A 45-year-old male requested both functional and cosmetic reconstruction of his defected penis, caused by an iatrogenic urethral injury and chronic infection following removal of paraffin self-injected on the penile shaft. The defect affected the full length of the penile urethra, corpus spongiosum, and prepuce. A groin flap was designed, measuring $28{\times}10cm$. The most distal flap was utilized for the construction of the luminal surface of the neourethra; relaxed length measuring 8 cm, and the lumen wide enough. Competent external meatus and neourethra was confirmed by retrograde cystogram and the patient voided with sufficient urine caliber up to 2 years follow-up. This operative technique has advantages. Donor sites have non-hair bearing skin for the neourethra and minimal or almost notrecognizable donor site morbidity. After surgery, the patient was relieved from voiding difficulties combined with psychological stress. The author would like to introduce a unique approach for the urethral and ventral phalloplasty using the groin flap.

• 한국화재소방학회논문지
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• 제27권5호
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• pp.1-7
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• 2013

가연물의 증가는 건축물 화재의 발생 위험성과 재해발생 규모를 점차적으로 증대시키는 요인이 되고 있다. 따라서 강구조 건축물의 화재에 대비한 기술개발이 요구되었으며, 이 결과로 내화강재가 개발되었다. 본 연구에서는 FR 490강재의 고온 시 기계적, 열적 특성을 실험적으로 평가하고, 이 결과를 상온 시 구조적 내력이 동일한 용접구조용 강재인 SM 490과 상호 비교함으로써 고온 시의 내력유지 성능이 우수함을 확인하였다.

• 한국주조공학회지
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• 제30권6호
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• pp.210-216
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• 2010

The aim of this study is to characterize a thixoextruded 7075 Al wrought alloy bar in terms of its isotropic behavior through the optical microscope, mechanical test and electron back scattered diffraction. It is also discussed of the extrudability improvement for 7075 Al wrought alloy by thixoextrusion, with emphasis on controlling thixoextrusion parameters. Hot extrusion shows that the maximum extrusion pressure depends on their characteristics in terms of flow stress and hot workability. In the contrary, thixoextrusion demonstrates that the maximum extrusion pressure is almost uniform regardless of the experimental parameters, such as initial ram speed, die bearing length and thixoextrusion temperature. The hot extruded microstructures become elongated to extrusion direction, while the thixoextruded microstructures are isotropic and homogeneously distributed due to the existence of liquid phase between solid grains during the process. The grain refinement due to dynamic recrystallization during thixoextrusion has been also occurred. Subsequent recrystallization would lead to the strengthening of mechanical properties, as observed in the study. The important point is that the values of tensile, yield strength and elongation of the thixoextruded bar without plastic deformation are similar to those of the hot extruded bar with severe plastic deformation.

• 한국지반공학회논문집
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• 제30권8호
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• pp.5-11
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• 2014

본 연구의 목적은 신뢰성해석을 통해 교량의 하부구조인 교대에 대해 주요설계변수와 신뢰성계수의 관계를 정립하여 하중저항계수설계를 위한 신뢰성해석방법을 개발하는 것이다. 하중조건으로는 사하중, 연직토압 및 수평토압, 상재하중, 그리고 통행차량에 의한 활하중을 고려하였다. 고려한 하중에 대해 지반의 허용지지력, 전도, 활동 등을 반영하는 한계상태함수를 정의하여 신뢰성 해석을 몬테-카를로 시뮬레이션을 이용하여 수행하였다. 신뢰성 해석 결과 신뢰성지수에 가장 큰 영향을 미치는 인자는 내부마찰각이었으며 민감도해석 결과 신뢰성 지수는 저항계수와 수평토압의 변화에 따라 민감하게 변화하는 것을 알 수 있었다.

• Steel and Composite Structures
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• 제19권3호
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• pp.661-678
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• 2015

Buckling Restrained Braces (BRB) have been widely used in the construction industry as they utilize the most desirable properties of both constituent materials, i.e., steel and concrete. They present excellent structural qualities such as high load bearing capacity, ductility, energy-absorption capability and good structural fire behaviour. The effects of size and type of filler material in the existed gap at the steel core-concrete interface as well as the element's cross sectional shape, on BRB's fire resistance capacity was investigated in this paper. A nonlinear sequentially-coupled thermal-stress three-dimensional model was presented and validated by experimental results. Variation of the samples was described by three groups containing, the steel cores with the same cross section areas and equal yield strength but different materials (metal and concrete) and sizes for the gap. Responses in terms of temperature distribution, critical temperature, heating elapsed time and contraction level of BRB element were examined. The study showed that the superior fire performance of BRB was obtained by altering the filler material in the gap from metal to concrete as well as by increasing the size of the gap. Also, cylindrical BRB performed better under fire conditions compared to the rectangular cross section.