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- 저자 : 이충환(Lee Chung Hwan) (검색결과 41 건)
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Head & Neck 환자의 방사선 치료시 Metal Artifact의 감소를 위한 Gantry Tilt Scan의 유용성 평가
이충환,윤인하,홍동기,백금문,권경태,Lee, Chung-Hwan,Yun, In-Ha,Hong, Dong-Gi,Back, Geum-Mun,Kwon, Gyeong-Tae 대한방사선치료학회 2010 대한방사선치료학회지 Vol.22 No.2
Purpose: The degradation of an image quality and error of the beam dose calculation can be caused because the metal artifact is generated during the CT simulation of head and neck patient. The usability of the gantry tilt scan for reducing the metal artifact tries to be appraised. Materials and Methods: The inferior $20^{\circ}$ gantry tilt scan was made in order to reduce the metal artifact and $0^{\circ}$ reconstruction image was acquired. The AAPM CT performance Phantom was used in order to compare the CT number of the reconstructed image and Original image. the difference of volume was compared by using the acrylic phantom. The homogeneity of the CT number was evaluated the Intensity volume Histogram (IVH) as in order to evaluate an influence by the metal artifact. A dose was evaluated as the Dose Volume Histogram (DVH). Results: in the comparison of the CT number and volume, the difference showed up less than 0.5%. As to the comparison of IVH, in the gantry tilt scan, influence by an artifact was reduced and the homogeneity of the CT number was improved. The comparison of DVH result reduced the mean dose error of the both sides parotid 0.2~6%. Conclusion: In the Head & Neck radiation therapy, It is difficult and to distinguish tumor and normal tissue and the error of dose is generated by the metal artifact. The delineation of the exact organization was possible if the Gantry tilt scan was used. The CT number homogeneity was improved and the error of dose could be reduced. The Gantry tilt scan confirmed in the Head & Neck radiation therapy to be very useful in the exact radiation therapy.
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플라즈마 스프레이 (LaSr)(CrCo)O<sub>3</sub> 코팅된 STS-430 합금의 고온 산화 거동 및 전기적 특성
이충환,임경태,백경호,Lee, Chung-Hwan,Lim, Kyeong-Tae,Baik, Kyeong-Ho 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.3
Fe-Cr steels are the most promising candidate for interconnect in solid oxide fuel cells. In this study, an effective, dense and well adherent (LaSr)(CrCo)$O_3$ [LSCC] coating layer was produced onto 430 stainless steel (STS-430) by atmospheric plasma spraying and the oxidation behavior as well as electrical properties of the LSCC coated STS-430 were investigated. A significant oxidation of pristine STS-430 occurred at $800^{\circ}C$ in air environment, leading to the formation of $Cr_2O_3$ and $FeCr_2O_4$ scale layer up to ${\sim}7{\mu}m$ after 1200h, and consequently increased an area specific resistance of $330\;m{\Omega}{\cdot}cm^2$. Although the plasma sprayed LSCC coating contained the characteristic pore network, the coated samples presented apparent advantages in reducing oxidation growth of STS-430, resulting a decrease in oxide scale thickness of ${\sim}1{\mu}m$ at $800^{\circ}C$ after 1200h. The area specific resistance of the LSCC coated STS-430 was much reduced to ${\sim}7\;m{\Omega}{\cdot}cm^2$ after exposure at $800^{\circ}C$ for 1200h, compared to that of the pristine STS-403.
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이충환(Chung Hwan Lee),김기선(Ki Sun Kim) 한국잡초학회·한국잔디학회 2003 Weed & Turfgrass Science Vol.17 No.1
본 실험은 답압에 의한 스트레스를 경감시킬 목적으로 폐타이어 칩을 한국잔디 식재 토양내 혼합 및 표면 배토시 그 효과를 평가하고자 실시하였다. 일반적으로 잔디는 답압이 진행됨에 따라 잔디 마모와 토양물리성이 나빠져서 생육은 감소하지만 폐타이어 칩을 토양내에 처리함으로써 토양경도, 표면 경도 등 토양물리성을 향상시키므로 생육을 향상시킬 수 있었으며, 토양 혼합처리는 가는 입자20% 처리구에서 좋은 토양물리성을 보였다. 배토처리시에는 무처리구와 비교시 표면의 높은 온도와 더불어, 피복효과와 마모를 가장 많이 받는 줄기 밑부분을 보호해 줌으로써 잔디 생육을 향상시킬 수 있었으며, 굵은 입자 10cm 처리구에서 표면온도가 높았다. 무기질인 폐타이어 칩을 소량으로 토양 혼합 및 배토처리함으로써 장기적인 효과가 예상되므로 향후 잔디면 조성 및 관리시에 이용할 만한 가능성이 있다고 생각된다. The objective of this study was to evaluate the effects of crumb rubber recycled from used tires as a soil incorporation and topdressing materials on a trafficked Korean lawngrass 'Zenith' (Zoysia japonica). In Exp 1, incorporation treatments included three particle sizes (PS: coarse = 4~6.35 mm, medium =2~4 mm, and fine =less than 2 mm in diameter) and two incorporation rate (IR: 10 and 20%). Wear treatments were applied 30 passes per day by compactor weights being 60 kg with soccer shoes. Topdressing treatments included three PS and two topdressing depth (TD; 5 and 10 mm). Wear treatments were the same as described in Exp 1. In Exp 1, the treatment with medium PS + IR 20 resulted in the tendency to have high total clipping yield. There was no significant difference in clipping yield, turfgrass visual color, coverage, and root length among the treatments. Compared to control, tissue Zn levels increased about 6.5-fold by the treatments. The treatment with fine PS+IR 20 caused a less peak deceleration than coarse PS+IR 10. Total porosity, air-filled porosity, and capillary porosity increased with fine PS + IR 20. In Exp 2, compared to controls, however, there was a difference in turfgrass visual color after the termination of traffic treatment. There was no difference in root length. The treatment with fine PS + TD 10 resulted in the highest total clipping yield. As a result of soil physical analysis, soil penetration resistance was reduced by the treatments. The treatment with coarse PS resulted in a less peak deceleration than fine PS. In conclusion, turfgrass growth was increased by crumb rubber incorporation which enhanced soil physical properties. The crumb rubber topdressing was able to cushion the crown tissue area while still providing a smooth and uniform surface, improve overall turf grass quality, and reduce compaction.
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전국 지방자치단체 출산장려정책 현황과 출산율에 미치는 영향력 분석
이충환 ( Chung Hwan Lee ),신준섭 ( Jun Seob Shin ) 한국지방행정연구원 2013 地方行政硏究 Vol.27 No.1
The purpose of this study was to investigate the activation level of childbirth policies by local governments and their effect on birthrates. The data on current status of childbirth policies were collected through a national survey on local government employees who were in charge of childbirth policies in local governments except for Jeju-do. Data Base of KOSIS(Korean Statistical Information Services) were used for childbirth rate and socioeconomic factors on local governments in 2009. Major findings included that healthcare support, information supply, child care support policies have been actively promoted. However, policies on childbirth-friendly social atmosphere and manpower/supplies support have been poorly activated implying a need to promote balanced policies to encourage childbirth. The activation level of the policies were not differ by local governments` socio-economic characteristics. A multiple regression analysis on birthrate in 2009 revealed that the only significant positive effect of economic support policy on birth rate suggesting a limited effect of the policies on the birthrate. Among the economic support policies, a significantly positive effect was detected in childbirth grant policy only. Based on these results, a need for more balanced childbirth polices and for reconstruction of current policy responses to encourage childbirth were suggested.
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이충환 ( Chung Hwan Lee ) 고려대학교 스포츠과학연구소 2008 스포츠문화과학연구 Vol.14 No.-
본 연구는 시각장애인의 여가태도와 여가제약을 연구하는데 목적이 있다. 연구의 목적을 달성하기 위해 수도권에 소재한 시각장애인 학교에서 수집된 자료는 연구목적에 의거 분산분석 방법을 통해 분석되었다. 이상과 같은 연구방법과 자료분석 결과를 토대로 얻어진 연구의 결론은 다음과 같다. 첫째, 시각장애인의 여가태도는 인구사회학적 변인 중 장애시기만이 정의적 태도에서 유의한 것으로 나타났으며, 선천성 집단이 후천성 집단보다 더 긍정적으로 조사되었다. 둘째, 시각장애인의 여가제약은 인구사회학적 변인 중 장애시기에서 인간내적 제약과 구조적 제약에서 유의한 것으로 나타났으며, 선천성 집단이 후천성 집단보다 더 높게 조사되었다. The Leisure Attitude Scale was composed of 3 components-cognitive attitude, affective attitude, behavioral attitude, which evaluated, the belief and knowledge of leisure, the feeling and preference, and experience and activities. The Leisure Constraints Scale examine the 3 parts-intrapersonal constraint, interpersonal constraint, structural constraint. What the limitation, the following conclusions were drawn: 1) The blind students showed the limitation of leisure activities, compared whit normal students. 2) There were no significant differences in all variables except the times of blindness in affective domain of leisure attitude. 3) There were significant differences in the intrapersonal and structural constraints. The congenitally blind students expierenced the high constraints. 4) The blind students showed the different expectation of value, of life, leisure attitude, sex role, and etc.
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청소년의 비행에 미치는 자기통제력과 사회자본의 영향연구
이충환(Lee Chung Hwan) 한국교정복지학회 2016 교정복지연구 Vol.- No.43
청소년의 비행과 관련하여 중요한 요인으로 연구된 자기통제력이나 공격성 등은 주로 개인의 특성에 관련된 영역으로서 사회적 환경의 영향력은 많이 연구되지 않았다. 이에 본 연구는 사회자본과 자기통제력을 독립변수로 하고 공격성을 매개변수로 하며, 비행유인을 종속변수로 하는 모형을 사용하여 청소년 비행에 대한 이해를 높이려고 하였다. 연구결과 자기통제력은 선행연구와 마찬가지로 공격성을 부분매개하여 비행유인에 영향을 미치고 있었고, 사회자본이 공격성을 부분매개하는 간접효과는 자기통제력의 간접효과에 비해 낮지만 직접적으로 비행유인에 비치는 영향은 높은 것으로 나타났다. 이와 같은 연구결과는 청소년 비행을 개인의 차원뿐만이 아닌 사회구조적 차원에서도 접근해야 할 필요성을 말해준다. It has not been investigated sufficiently the influence of social environment on self-control or aggression which has been examined as the important factor related to juvenile delinquency because self-control or aggression is related mainly to individual characteristics. Thus, this paper tried to improve the understanding on the juvenile delinquency using the model which adopted the social capital and self-control as the independent variables, aggression as the mediating variable and delinquency inducement as dependent variable. In accordance with the analysis, self-control had the impact on the delinquency inducement through aggression as the mediator in part as indicated in the previous research. While the indirect impact of social capital with aggression as the partial mediator was lower than that of self-control, social capital showed higher indirect impact on the delinquency inducement. The analysis results pointed out that it would be required to get access to the juvenile delinquency not on the individual dimension but on the social structural dimension.
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