• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.741-747
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• 2010

The feasibility of using ammonium (${NH_4}^+$) and potassium ($K^+$)-loaded zeolite (NK-Z) as a slow-release fertilizer to control nitrogen and potassium supply was investigated in this study. The growth responses, which were determined in terms of shoot length, shoot fresh weight, and fresh fruit weight, were greater in plants treated with NK-Z than in those treated with chemical fertilizers (CF) after 18 weeks of transplantation. The total fruit weight per plant in treated with NK-Z as the basal and additional fertilizer (ZBAF) was 14.89% higher than that of CF. The nitrogen and potassium contents in NK-Z amended soils were higher than those in CF amended soils in the final stage of plant growth. The ammonium nitrogen ($NH_4$-N) concentration in ZBAF amended soils was 63.41% higher than that in CF amended soils.

• Explosives and Blasting
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• v.31 no.1
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• pp.64-75
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• 2013

This case study deals with an excavation blasting carried out at "Sooseo-Pyeongtek ${\bigcirc}$-${\bigcirc}$ section construction site" in the vicinity of residential area. Originally, the sequential blasting (multi-stage blasting) using electric detonators was planed in this area. However, there was a concern that the sequential blasting method could increase the construction cost by delaying the construction period due to possible complaints from local residents. As an alternative, electronic deck blasting technique was taken in order to meet the ground vibration regulation (0.2cm/s, in apartment area) and to keep the construction schedule. The performance of the electronic deck charge blasting was two times better than the sequential blasting with electric detonators and the level of ground vibration was also within the regulatory value (0.2cm/s). In particular, it was shown that the use of electronic detonater eDevII, which was developed for tunnel, could provide more convenient and electrically safer working condition.

• Korean Journal of Construction Engineering and Management
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• v.7 no.4 s.32
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• pp.61-68
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• 2006

Safety is the most important issue in the construction industry. Especially, work-related disease is increasing and resulted in lack of young workers and high turnover due to its 3D industrial image. The main objective of this paper is to identify the relationship of WRMSD with hand tools used in the building construction industry. In order to reach to the goals, the survey and interviews with laborers are conducted. The data is analyzed in a statistical manner. One of the interesting findings from the research is that the carpenters and steelworkers are the principal trade group suffering from WRMSD due to unsafe working condition and method. The results of the research will be used as the basis for the ergonomic design of the better construction working condition and hand tools.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.345-353
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• 1987

An analysis is performed to study flow and heat transfer characteristics of mixed free and forced convection about a sphere. Nonsimilar boundary layer equations which are valid over the entire regime of mixed convection are derived in terms of the mixed convection parameter, Gr/Re$^{2}$, through a dimensional analysis. The transformed conservation equations are solved by a finite difference method for the whole range of mixed convection regime. Numerical results for fluids having the Prandtl number 0.7 and 7 are presented. As the mixed convection parameter increases, the local friction coefficient and local heat transfer coefficient increases as well. For small Prandtl number, the friction coefficient is larger, while for large Prandtl number, the heat transfer coefficient is larger. Natural convection effect on the forced flow is more sensitive for small Prandtl number fluid. Flow separation migrates rearward as an increase in the mixed convection parameter. For small Prandtl number, the buoyancy effect is relatively small so that the flow separation occurs earlier.

• Polymer(Korea)
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• v.32 no.3
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• pp.193-198
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• 2008

Sibutramine is a highly crystalline and poorly water soluble drug as the appetite depressant for obesity treatment. In order to increase water solubility of sibutramine, microspheres including sibutramine were prepared by solid dispersion method using a spray dryer. The crystallinity and morphology of the prepared microspheres were confirmed by SEM and XRD. The morphology of micro spheres has gradually changed into spherical shape as increasing evaporation rate of solvent. According to XRD analysis, crystallinity of sibutramine in micro spheres was decreased by below 10%. Release behavior of microspheres was investiaged at pH 1.2, pH 6.8, and solubility of the sibutramine was significantly different depending on pH. The hard capsule showed fast release of sibutramine comparing with the tablet. These results demonstrated that the pharmaceutical preparation is able to control the release behaviors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.37-37
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• 2009

박막태양전지는 p-i-n substrate형과 n-i-p substrate형 두가지구조로 제조된다. 각 layer에서 activation energy와 band gap energy를 ASA simulator를 통해 조절해보았다. Simulation결과 p-i-n substrate형에서 p-layer와 n-i-p substrate형 n-layer에서 동일하게 activation energy 0.2eV, band gap energy 1.80eV에 최고효율 나왔고 각각 10.07%, 10.17%의 최고효율을 구할 수 있었다. 최적화 과정을 통하여 같은 조건에서 p-i-n substrate형 보다 n-i-p substrate형이 보다 높은 효율을 낸다는 것을 알 수 있었으며 본 연구를 통해 각 구조의 차이를 알 수 있었고 이는 높은 효율의 박막태양전지 설계에 도움이 될 것 이다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.492-495
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• 2009

본 논문에서는 유한대판법(Finite Strip Method, FSM)을 이용하여 복합재료로 구성된 박판구조물의 좌굴해석을 수행하였다. 유한대판법에서의 변위장은 정현곡선으로 구성된 X방향 성분과 여현곡선의 Y방향 성분으로 구성되어 있는 면내성분, 면외성분으로 횡방향으로 3차 다항식과 보 진동함수를 사용하여 구성되었다. 각 적층판의 강성을 두께방향으로 적분하여 전체 강성을 구하고 최소 포텐셜 에너지 이론을 사용하여 구한 평형방정식에 대입하여 전체 강성행렬을 구하였다. 자유도의 감소로 인한 해석시간의 단축, 입력자료 작성 및 출력이 쉬운 점들이 유한대판법을 이용한 좌굴해석의 장점이다.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.341-344
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• 2000

본 논문에서는 복잡한 배경이나 조명 변화가 심한 영상에서도 피부영역을 정확하게 검출할 수 있는 피부영역 검출방법을 제안한다. 제안된 방법은 오프라인(off-line) 훈련과정과 온라인(on-line) 검출과정의 두 단계로 나누어진다. 훈련단계에서는 다양한 조명하에서 얻은 피부영상과 배경영상으로 구성된 훈련영상을 다차원의 열벡터로 표현하고 열벡터에 LDA(linear discriminant analysis)를 적용하여 선형변환된 특징벡터를 가지고 인덱싱 테이블을 생성한다. 검출단계에서는 카메라로 들어온 칼라영상을 여러 개의 조각영상으로 나누고 각각의 조각영상에 대하여 LDA를 적용하여 선형변환된 특징벡터를 구한다. 구해진 특징벡터를 미리 생성한 LDA 인덱싱 테이블에서 찾아 피부영역을 검출한다. 제안된 방법을 조명을 변화시킨 다양한 영상에 적용하여 실험한 결과 검출률이 상당히 우수함을 알 수 있었다.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1103-1109
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• 2010

In this paper in order to analyze the mechanical properties, the permeability and the freezing properties of SB-2 materials which are mainly used with the subbase materials on the rod. For this ends, a series of the physical test, the permeability test and the freezing test were carried out the samples mixed the small aggregate and the big aggregate from which was re-classified the SB-2. From the test results, it was analyzed the characteristics of permeability and the characteristics of freezing of the samples.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.443-444
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• 2008

본 논문에서는 비행기 모델을 대상으로 invariance and immersion방법을 적용하여 비선형 제어기를 설계한다. 이 방법을 사용하면 추정오차에 대한 추정식 형태로 off-the-manifold 좌표축을 정의하고, dynamics를 구하고, 이로부터 파라미터 적응규칙을 유도한다. 제어기는 이와 관련된 파라미터로부터 선형 화하지 않고 직접 설정하며, 마지막으로 리아프노프 함수를 통하여 알고리즘의 안정성을 증명한다.