• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.326-331
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• 2000

In this study, residual stress was investigated experimentally to evaluate damaged layer in high-sped machining. In machining difficult-to-cut material, residual stress remaining in machined surface was mainly speared as compressive stress. The scale of this damaged layer depends upon cutting speed, feed per tooth and radial cutting depth. Damaged layer was measured by optical microscope. The micro-structure of damaged layer was a mixed maternsite and austenite. depth of damaged layer is increased with increasing of cutting temperature, cutting force and radial depth. On the other hand, that is slightly decreased with decreasing of cutting force. The increase of tool wear causes a shift of the maximum residual stress in machined surface layer.

• International Journal of Safety
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• 제10권1호
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• pp.16-21
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• 2011

In this thesis, appearance inspection, compressive strength of concrete test, arrangement of bar inspection, survey, and bearing stress analysis were performed on a damaged coping of reinforced concrete pier to investigate the damage cause. According to the performed a series of inspections, it was found that the coping of pier was damaged during PSC (Pre-stressed Concrete) beam construction. In this thesis, the repair method for damaged pier was studied. The repair procedure used in this thesis was follows : chipping for damaged part, clean by high-pressure, installation of wire mesh, coating of surface hardening, construction of section restoration material, copula grinding, and prevent coating for far-infrared radiation.

• 대한조선학회논문집
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• 제43권4호
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• pp.451-459
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• 2006

When a ship is damaged and flooded, the motion of the damaged ship is significantly influenced by the flooding water dynamics. The flooding water in the damaged ship has been treated as a lumped mass under the quasi-static assumption in most of previous researches. To calculate the motion of damaged ship rigorously, it is necessary to analyze the coupled dynamics of flooding water. In this study, a series of numerical and experimental studies is conducted for the damaged part of ITTC RORO passenger. FLOW3D is used for investigating the feasibility of the state of the art CFD technique. An applicability of the coupled motion analysis of damaged ships can be confirmed by agreement between the numerical results and the model experiments. A CFD technique is considered for the numerical modeling of the dynamics of flooding water.

• Journal of the Korean Wood Science and Technology
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• 제31권4호
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• pp.1-7
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• 2003

본 연구에서는 산불 피해를 입은 소나무재의 유효 활용을 위한 기초자료를 얻고자 해부 및 물리학적 특성을 조사하였다. 산불 피해재의 수지구, 에피델리얼세포와 방사유세포내에는 건전재와 달리 과립모양의 물질이 많이 존재하였으며, 그 외의 목부 조직구조는 정상재와 거의 차이가 없었다. 건전재와 비교하여, 산불 피해재는 상대결정화도가 다소 높았으며, 생재함수율과 접선 및 방사단면 흡수량은 다소 낮게 나타났다. 수축율 및 팽윤율과 기본밀도는 정상재와 거의 유사한 값을 보여주었다.

• International Journal of Concrete Structures and Materials
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• 제7권1호
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• pp.35-50
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• 2013

Rapid and effective repair methods are desired to enable quick reopening of damaged bridges after an earthquake occurs, especially for those bridges that are critical for emergency response and other essential functions. This paper presents results of tests conducted as a proof-of-concept in the effectiveness of a proposed method using externally bonded carbon fiber reinforced polymer (CFRP) composites to rapidly repair severely damaged RC columns with different damage conditions. The experimental work included five large-scale severely damaged square RC columns with the same geometry and material properties but with different damage conditions due to different loading combinations of bending, shear, and torsion in the previous tests. Over a three-day period, each column was repaired and retested under the same loading combination as the corresponding original column. Quickset repair mortar was used to replace the removed loose concrete. Without any treatment to damaged reinforcing bars, longitudinal and transverse CFRP sheets were externally bonded to the prepared surface to restore the column strength. Measured data were analyzed to investigate the performance of the repaired columns compared to the corresponding original column responses. It was concluded that the technique can be successful for severely damaged columns with damage to the concrete and transverse reinforcement. For severely damaged columns with damaged longitudinal reinforcement, the technique was found to be successful if the damaged longitudinal reinforcement is able to provide tensile resistance, or if the damage is located at a section where longitudinal CFRP strength can be developed.

• 패션비즈니스
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• 제12권6호
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• pp.11-22
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• 2008

The goal of this study is to provide beauticians with the fundamental material to use effectively heat permanent wave in beauty industry as well as their customer's satisfaction. It carried out an experiment with damaged hair of a woman in her late twenties to investigate the change of physical and morphological characteristics by its water content when performing heat permanent wave. After spreading 0g, 1g, 2g, 3g, and 4g of water on damaged hair respectively, heat permanent wave was treated and the change of hair was observed. The change of physical characteristic was compared through permanent wave form of hair, tensile strength and elongation. The change of morphological characteristic was observed through Scanning Electron Microscope(SEM) and Transmission Electron Microscope(TEM). The result of experiment on the physical specificity revealed that permanent wave form was the most ideal when the water content was 2g, also 3g. Though the materials with much moisture content formed the results were not satisfied. The material with 0g of water content didn't make the wave. In terms of tensile strength and elongation, tensile strength was generally reduced as per the damaged degree of hair. On the contrary, elongation was increased. It observed the changes of morphological characteristic that the damage on hair cuticle was deepen, as its moisture content was decreased, and cuticle's surface was worn away. The observation of fine structure on hair section by transmission electronic microscope also certainly showed the result that damaged hair having experience with chemical treatment had got much damaged to hair cuticle as well as hair cortex. Generally chemical treatment makes hair damaged. Under consideration of this aspect, the ultimate goal of this thesis is to minimize the damage of hair caused by chemical treatment and get the satisfaction on the hair style. According to the result of experiment, the damaged hair whose moisture content was 3g showed the best permanent wave form.

• Journal of the Korean Wood Science and Technology
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• 제36권4호
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• pp.84-92
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• 2008

강원도 양양 지역 산불 피해 소나무 목재의 피해 정도에 따른 해부 및 물리적 특성을 조사하였다. 피해 정도에 따라 수피의 탄화 깊이가 깊어지는 경향이 관찰되었으나 목질부까지 탄화가 진행되지는 않았으며 수지의 삼출정도에 차이를 보였다. 산불 피해목 변재의 생재함수율은 건전재보다 다소 낮게 나타났으나 심재의 경우에는 건전재보다 피해목이 다소 높게 나타났다. 생재밀도는 피해재 심재가 건전재 심재보다 다소 높게 나타났으며, 변재에서는 차이를 보이지 않았다. 형성층대를 관찰한 결과, 산불 피해를 강하게 입은 경우 형성층의 활동이 일어나지 않았고, 비교적 피해를 약하게 입은 경우에는 형성층의 활동이 관찰되었으나 세포분열 속도는 건전재보다 느렸다. 산불 피해를 강하게 입은 목재에서는 에피델리움세포와 방사조직의 세포벽이 짙게 염색되고 세포내에 과립형태의 물질이 관찰되었으며, 최외각 연륜 부위의 결정화도는 산불 피해재가 건전재보다 다소 높게 나타났다.

• 한국산림과학회지
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• 제70권1호
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• pp.55-62
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• 1985

본(本) 연구(硏究)는 경남(慶南) 진주지역(晋州地域)에서 발생(發生)한 야서(野鼠)의 맹종죽순(孟宗竹筍) 피해(被害)에 관해서 조사(調査)하여 피해죽림분(被害竹林分)의 주변(周邊)과 내(內)의 식생(植生)을 분석(分析)하고 서식환경(棲息環境)을 파악하여, 피해정도(被害程度)와 피해율(被害率), 가해야서(加害野鼠)의 종류(種類)를 밝혀 피해예방(被害豫防) 및 구제(驅除)에 기여코져 실시하였다. 그 결과(結果) 피해죽림(被害竹林) 주변(周邊)의 입목도(立木度)와 서식환경(棲息環境)에 따라 피해도(被害度)에 영향을 미쳤으며, 피해도(被害度)는 ha당(當) 7.1개(個)로 4,359.1g이었고, 피해율(被害率)은 0.23%이었다. 피해시기(被害時期)는 4월(月) 중순(中旬)에 시작되어, 4월(月) 23일(日)경에 최고에 달하고 5월(月) 중(中) 하순(下旬)에 종료(終了)되었다. 피해죽순(被害竹筍)의 평균장(平均長)은 28.12cm, 직경(直徑) 7.49cm, 무게 613.96g이었으며, 부위별(部位別) 피해형(被害型)은 지상(地上), 지표(地表), 지하피해형(地下被害型) 중에서 지상(地上), 지하피해형(地下被害型)이 많았다. 피해죽림분(被害竹林分) 내(內)에서 포획(捕獲)된 야서(野鼠)는 쥐목(目)에 속하는 등줄쥐와 생쥐, 그리고 식충목(食蟲目)에 속하는 우수리땃쥐 등(等) 3종(種)이었으며 주가해종(主加害種)은 등줄쥐와 생쥐 중 등줄쥐가 많았다. 또한, 우수리땃쥐는 남부지방(南部地方)에 서식(棲息)함이 처음 발견(發見)되었다.

• 생태와환경
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• 제55권4호
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• pp.330-340
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• 2022

이 연구는 환경영향평가 개발사업 시 발생하는 훼손수목 탄소저장량의 적합한 산정방법에 대해 논의하고자 수행되었다. 이를 위해, 훼손수목이 발생하는 재생에너지 관련 개발사업 9개를 선정하여 훼손수목 탄소저장량의 평가현황 및 방법을 정리하였다. 그리고 상대생장식을 활용하여 훼손수목 탄소저장량을 재산정 한 후 보고서의 훼손수목 탄소저장량과 비교하여 두 집단 간 차이를 검증하였다. 그 결과 개발사업의 보고서의 훼손수목 탄소저장량은 재산정 탄소저장량 보다 큰 것으로 나타났고 통계적으로 유의성이 있었다(p<0.005). 이는 기존의 훼손수목 탄소저장량 산정이 과다 산정되고 있음을 나타내며 산정 방법의 개선이 필요한 것으로 판단된다. 따라서 훼손수목의 탄소저장량 산정 시 우리나라 산림의 우점 수종에 적합한 상대생 장식을 사용해야 한다. 더 나아가, 사용자들이 효율적이고 정확하게 훼손수목 탄소저장량을 산정할 수 있도록 생태계의 실측 데이터에 기반한 탄소저장량 산정 시스템을 구축하여 사용할 것을 제안한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.778-781
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• 2004

As the technique of high-speed end-milling is widely adopted to in machining field. The investigation for microscopic precision of workpiece is necessary for machinability evolution. In this study, cutting force, cutting temperature and microhardness were investigated to evaluate damaged layer in conventional machining and high-speed machining. Damaged layer was measured using optical microscope. The thickness of damaged layer depends on cutting process parameters, specially feed per tooth and radial depth. It is obtained that the characteristics of damaged layer is high-speed machining better than conventional machining.