• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.249-254
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• 2003

분석에 이용된 격자망은 동곡, 고로, 미성, 병천, 효령 및 무성지점에 각각 12개, 30개, 45개, 76개, 46개 및 1265개의 조격자를 구성하였으며 하천의 수로방향 및 경사형태를 세분화하기 위하여 각 지점에 대하여 8개, 24개, 24개, 44개, 12개 및 64개의 세격자로 분할하였다. AGNPS를 이용한 첨두유량의 모의발생 결과치가 동곡, 고로, 미성, 병천, 효령 및 무성지점에서 측정값과 비교하여 각 호우사상별로 상대오차가 1.0~25.0%, 4.0~27.0%, 7.0~29.2%, 2.0~23.9%, 3.0~25.0% 및 3.6~21.0%의 차이를 나타내었다. 분석결과에서 AMCII조건에서는 관측치와 분석결과치가 유사하게 나타났으나 AMCI조건에 대해서는 상대적으로 작은 값을 보였으며 AMCIII조건에서는 다소 큰 값으로 분석되었다. SCS방법에서 제안하는 AMC조건별 CN값을 우리 실정에 적합하도록 수정 보완하기 위한 수정 유출곡선지수 $CN_{m}$ /I과 $CN_{m}$/III을 재구성하였으며, 여기에 적용되는 수정 유출 곡선지수식의 계수 a를 추정한 결과, 기왕에 발표된 연구결과와 거의 일치된 경향을 나타내었다. 제안된 수정 CN식을 이용하여 산정한 결과치와 관측치는 거의 유사하게 나타났다. AGNPS모델에 의한 유출량 산정에 있어 수문학적 토양피복형수(CN)의 결정을 위하여 선행강우량과 토양의 공극율 및 지형인자인 각 셀마다의 유역경사를 이용하여 관계식(CN =f($X_1$, $X_2$, $X_3$))을 유도하였으며, 분석 결과에서 CN이 선행강우량과 가장 밀접한 관계가 있음을 알 수 있었으며 유역경사, 토양의 공극율 순으로 나타났다..88mg/$\ell$~의 범위로 나타났다. 무태교 지점에서의 총인의 농도는 0.52mg/$\ell$~0.99mg/$\ell$~의 범위이었다. 신천에 금호강물을 혼합한 이후에도 부유물질, 생화학적산소요구량, 암모니아태 질소, 총인 등의 농도가 개선되지 않았다. 즉 금호강물의 혼합은 신천수질환경사업소에서 배출되는 방류수에 함유되어 있을 2차 오염물질의 희석이라는 이점외의 수질개선효과는 확인되지 않았다.l years and a new type of transfer crane has been developed. Design concepts and control methods of a new crane will be introduced in this paper.and momentum balance was applied to the fluid field of bundle. while the movement of′ individual material was taken into account. The constitutive model relating the surface force and the deformation of bundle was introduced by considering a representative prodedure that stands for the bundle movement. Then a fundamental equations system could be simplified considering a steady state of the process. On the basis of the simplified model, the simulation was performed and the results co

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.292-296
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• 2003

Autoclaving처리를 하지 않은 키토산과 autoclaving처리한 키토산과의 중금속 흡착실험을 해 본 결과 다음과 같은 결과를 도출 할 수 있었다. 1) 먼저 중금속간의 흡착능을 고찰하기 위하여 Langmuir와 Freundlich 흉착등온식에 적용시켜 본 결과 Freundlich 흡착등온식 보다는 Langmuir 흡착등온식이 보다 적합한 것으로 나타났다. 2) 시간에 따라서 autoclaving 처리한 키토산의 중금속 제거 가능성과 그 효율을 검토하기 위하여 각 중금속간의 Langmuir 흡착등온식을 이용하여 $q_{max}$를 나타냈다. 15 min > 60 min > 0 min 순으로 모든 중금속 제거 실험에서 15 min 동안 autoclaving 처리한 키토산의 중금속 흡착량이 가장 높은 것으로 나왔다. 그러므로 기존의 키토산 보다는 15 min동안 autoclaving 처리한 키토산이 중금속 제거에 더 좋은 흡착제로써 역할을 할 수 있을 것으로 판단된다. 3) 키토산을 이용한 중금속 제거에서는 $Pb^{2+}$ > $Cd^{2+}$ > $Cu^{2+}$ > $Cr^{3+}$순서로 제거가 되었다. 여러 연구자들의 실험 결과를 종합해 볼 때 Pb$^{2+}$가 중금속 중에 제거가 잘 된다는 연구 결과가 많이 발표 되었으며, $Cd^{2+}$, $Cu^{2+}$, $Cr^{3+}$의 경우에는 흡착제의 종류에 따라서 제거되는 순서가 다르다는 연구 결과들이 보고 되고 있다. 그러나 어떠한 이유로 중금속의 제거에 차이가 있는지에 대해서는 명확한 결론이 내려져 있지 않는 실정이다. 이러한 중금속간의 경쟁적인 관계에 대해 더 많은 세밀한 연구가 이루어져야 할 것 같다.는 0.52mg/$\ell$~0.99mg/$\ell$~의 범위이었다. 신천에 금호강물을 혼합한 이후에도 부유물질, 생화학적산소요구량, 암모니아태 질소, 총인 등의 농도가 개선되지 않았다. 즉 금호강물의 혼합은 신천수질환경사업소에서 배출되는 방류수에 함유되어 있을 2차 오염물질의 희석이라는 이점외의 수질개선효과는 확인되지 않았다.l years and a new type of transfer crane has been developed. Design concepts and control methods of a new crane will be introduced in this paper.and momentum balance was applied to the fluid field of bundle. while the movement of′ individual material was taken into account. The constitutive model relating the surface force and the deformation of bundle was introduced by considering a representative prodedure that stands for the bundle movement. Then a fundamental equations system could be simplified considering a steady state of the process. On the basis of the simplified model, the simulation was performed and the results could be confirmed by the experiments under various conditions.뢰, 결속 등 다차원의 개념에 대한 심도 깊은 연구와 최근 제기되고 있는 이론

• Journal of Chest Surgery
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• v.35 no.4
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• pp.255-260
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• 2002

Paraplegia remains unresolved as the most dreaded operative complication with surgical treatment of descending thoracic and thoracoabdominal aortic diseases. In this study, the neuroprotective effect of trimetazidine that has been used clinically for ischemic heart disease was investigated in a rabbit spinal cord ischemia model. Material and Method: Thirty-three New Zealand white rabbits were randomized as follows: control group undergoing abdominal aortic occlusion but receiving no pharmacologic intervention(Group 1, n= 17); TMZ group(Group 2, n= 16) receiving 3 mg/kg trimetazidine intravenously before the occlusion of the aorta. Ischemia was induced by clamping the abdominal aorta just distal to the left renal artery for 30 minutes. Neurologic status was assessed at 2, 24, and 48 hours after the operation according to the modified Tarlov scale, then the lumbosacral spinal cord was processed for histopathologic examinations 48 hours after the final assessment. Result: The average motor function score was significantly higher in the TMZ group(3.20 $\pm$ 0.77 vs 1.13 $\pm$ 1.25 at 2 hours, 3.50 $\pm$ 0.76 vs 1.45 $\pm$ 1.57 at 24 hours, and 3.91 $\pm$ 0.30 vs 1.86 $\pm$ 1.86 at 48 hours after operation; p value$\leq$0.05). Histologic observations were correlated with the motor scores. Conclusion: The results suggested that trimetazidine reduced spinal cord injury during aortic clamping and that it may have clinical utility for the thoracoabdominal aortic surgery:

• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.79-85
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• 2019

'Experiments in Art and Technology' Group was established in the mid-20th century, and then developed the larger interdisciplinary experiments into the range of art world and its outside field. The motive power of group's activities was the collaboration between artists and engineers traversing the boundary between old different disciplinary conventions. E.A.T was officially launched in 1967 by the engineers Billy $Kl{\ddot{u}}ver$ and Fred Waldhauer and the artists Robert Raushenberg and Robert Whitman. They performed various possibility of material, technology, and engineering available to contemporary art. By reflecting the function of art and technology in society, eventually they developed the methodology of new aesthetics which had organic relationship with contemporary world. In this sense, this research have its academic significance. This paper firstly examined the socio-cultural context of emerging the E.A.T. group as a representative model for convergent practice, and verified the fact that the collaboration between artists and engineers had produced the expansion of artistic expression as well as new relationship among art, engineering, and society by considering E.A.T's various projects. Therefore, I will refer the E.A.T. group as an exemplary model for concrete method of collaboration that contemporary discourses about convergence need.

• Computers and Concrete
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• v.31 no.3
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• pp.267-276
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• 2023

The main purpose of the current research is to develop an efficient two variables trigonometric shear deformation beam theory to investigate the buckling behavior of symmetric and non-symmetric functionally graded carbon nanotubes reinforced composite (FG-CNTRC) beam resting on an elastic foundation with various boundary conditions. The proposed theory obviates the use to shear correction factors as it satisfies the parabolic variation of through-thickness shear stress distribution. The composite beam is made of a polymeric matrix reinforced by aligned and distributed single-walled carbon nanotubes (SWCNTs) with different patterns of reinforcement. The material properties of the FG-CNTRC beam are estimated by using the rule of mixture. The governing equilibrium equations are solved by using new analytical solutions based on the Galerkin method. The robustness and accuracy of the proposed analytical model are demonstrated by comparing its results with those available by other researchers in the existing literature. Moreover, a comprehensive parametric study is presented and discussed in detail to show the effects of CNTs volume fraction, distribution patterns of CNTs, boundary conditions, length-to-thickness ratio, and spring constant factors on the buckling response of FG-CNTRC beam. Some new referential results are reported for the first time, which will serve as a benchmark for future research.

• International Journal of Highway Engineering
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• v.19 no.5
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• pp.107-115
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• 2017

PURPOSES : The piezoelectric energy road analysis technology using a three-dimensional finite element method was developed to investigate pavement behaviors when piezoelectric energy harvesters and a new polyurethane surface layer were installed in field conditions. The main purpose of this study is to predict the long-term performance of the piezoelectric energy road through the proposed analytical steps. METHODS : To predict the stresses and strains of the piezoelectric energy road, the developed energy harvesters were embedded into the polyurethane surface layer (50 mm from the top surface). The typical type of triaxial dump truck loading was applied to the top of each energy harvester. In this paper, a general purpose finite element analysis program called ABAQUS was used and it was assumed that a harvester is installed in the cross section of a typical asphalt pavement structure. RESULTS : The maximum tensile stress of the polyurethane surface layer in the initial fatigue model occurred up to 0.035 MPa in the transverse direction when the truck tire load was loaded on the top of each harvester. The maximum tensile stresses were 0.025 MPa in the intermediate fatigue model and 0.013 MPa in the final fatigue model, which were 72% and 37% lower than that of the initial stage model, respectively. CONCLUSIONS : The main critical damage locations can be estimated between the base layer and the surface layer. If the crack propagates, bottom-up cracking from the base layer is the main cracking pattern where the tensile stress is higher than in other locations. It is also considered that the possibility of cracking in the top-down direction at the edge of energy harvester is more likely to occur because the material strength of the energy harvester is much higher and plays a role in the supporting points. In terms of long-term performance, all tensile stresses in the energy harvester and polyurethane layer are less than 1% of the maximum tensile strength and the possibility of fatigue damage was very low. Since the harvester is embedded in the surface layer of the polyurethane, which has higher tensile strength and toughness, it can assure a good, long-term performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.102-109
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• 2017

The high pressure pump of a diesel injection system compresses the fuel supplied at low pressure into high pressure fuel and maintains the fuel of the common rail at the required pressure level according to the engine operating conditions. The high pressure pump is required to operate normally in order to compress the fuel to a high pressure of 2000 bar during the entire lifetime of the vehicle. Consequently, a suitable design technique, material durability and high precision machining are required. In this study, the high pressure pump simulation model of a 1-plunger radial piston pump is modelled by using the AMESim code. The main simulation parameters are the displacement, flow rate and pressure characteristics of the inlet and outlet valves, cam torque characteristics, and operating characteristics of the fuel metering valve and overflow valve. In addition, the operating characteristics of the pump are simulated according to the parameter changes of the hole diameter and the spring initial force of the inlet valve. The simulation results show that the operation of the developed pump model is logically valid. This paper also proposes a simulation model that can be used for current pump design changes and new pump designs.

• Tunnel and Underground Space
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• v.30 no.4
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• pp.382-393
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• 2020

The engineered barrier system of high-level radioactive waste disposal must maintain its performance in the long term, because it must play a role in slowing the rate of leakage to the surrounding rock mass even if a radionuclide leak occurs from the canister. In particular, it is very important to clarify gas dilation flow phenomenon clearly, that occurs only in a medium containing a large amount of clay material such as a bentonite buffer, which can affect the long-term performance of the bentonite buffer. Accordingly, DECOVALEX-2019 Task A was conducted to identify the hydraulic-mechanical mechanism for the dilation flow, and to develop and verify a new numerical analysis technique for quantitative evaluation of gas migration phenomena. In this study, based on the conventional two-phase flow and mechanical behavior with effective stresses in the porous medium, the hydraulic-mechanical model was developed considering the concept of damage to simulate the formation of micro-cracks and expansion of the medium and the corresponding change in the hydraulic properties. Model verification and validation were conducted through comparison with the results of 1D and 3D gas injection tests. As a result of the numerical analysis, it was possible to model the sudden increase in pore water pressure, stress, gas inflow and outflow rate due to the dilation flow induced by gas pressure, however, the influence of the hydraulic-mechanical interaction was underestimated. Nevertheless, this study can provide a preliminary model for the dilation flow and a basis for developing an advanced model. It is believed that it can be used not only for analyzing data from laboratory and field tests, but also for long-term performance evaluation of the high-level radioactive waste disposal system.

• Korea Journal of Hospital Management
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• v.3 no.1
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• pp.62-82
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• 1998

The purpose of this study is to assess the cause and level of conflict arising within and between departments among administration office workers who work in a recently established tertiary hospitals of a major cooperation or related non-profit cooperation: The study also aimed to find methods for resolution of such conflicts by comparing with other existing university hospitals. The subject population included 299 business administration office workers randomly selected from two cooperate related tertiary hospitals of less than 3 years in its existence and two university hospitals over 700 beds in Seoul and Kyong In area. Data were collected through a survey questionnaire. To define related factors for the level of conflict among departments in each hospitals multivariate regression analysis was conducted. Independent factors were characteristics of subjects, conflicting factors within and between the departments. The results are as follows: 1. Those in the 30-39 rears of age group demonstrated significantly higher level of conflict between departments. Those working in the new hospitals, who were older and had long-term tenure, and those with short-term job experience at current working hospital had higher level of conflict between the departments with statistical significance. 2. Concerning the involvement of conflicting factors and the level of conflict in the administration there was statistically significant positive correlation between reliability and job-related intra- and interdepartmental level of conflict in existing hospitals. There was a significant positive correlation between intradepartmental conflicting factors of mutual dependence, difference in goal/orientation and intra- and interdepartmental level of conflict. 3. In multivariate regression analysis, women more than men, and those who had worked for many years in hospitals had statistically significant influence on factors involved in interdepartmental level of conflict, explaining 51.0% of the model. 4. In existing hospitals, gender was a significant factor with women showing a higher level of interdepartmental conflict compared to men. Among the interdepartmental factors, mutual dependence had statistically significant influence and showed a positive relationship with interdepartmental level of conflict. In the new hospitals, job position was a significant factor which showed that those in high position such as section chief or above, compared to those in managerial or general position had higher level of conflict. Among the interdepartmental characteristics, factors of mutual dependence and goal/orientation had statistically significant influence and showed a positive relationship with interdepartmental level of conflict. In the new hospital setting efforts to reduce conflict in areas among workers with high position, old age, and long tenure and those in Purchasing, Material and Computer Department should be made and prudent management and planning for improved manpower and increased budget or efficient allocation and clear definition of job description are necessary to adequately assess and make improved efforts for rapid stabilization of the premature hospital system from its inception, In the existing hospitals a lack of conflict within and between departments may give rise to stagnation or inefficiency of the organization. Future study are needed with respect to the relationship between interdepartmental level of conflict and the effectiveness of the hospital organization for improved resolution of conflict in the organization and hospital management.

• Applied Biological Chemistry
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• v.41 no.2
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• pp.187-190
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• 1998

The cytotoxic activity of MeOH extracts of the freeze-dried silkworm (Bombyx mori)-derived materials (4th instar larvae, female and mate pupae, virgin female and male adult), dried Beauveria bassiana-infected silkworm larvae, dried feces from the 4th instar larvae B. mori, and dried mulberry (Morus alba)-derived materials (leaves, fruits, root barks) in vitro was evaluated by sulforhodamine B assay, using the five human solid A 549 lung, SK-OV-2 ovarian, SK-MEL-2 melanoma, XF-498 CNS and HCT-15 colon tumor cell lines. The responses varied with both cell line and material used. The 70% hot MeOH extract of B. mori feces (BFH) revealed potent cytotoxic activity against model tumor cell lines whereas moderate activity was observed from the MeOH extract of B. mori feces. M. alba root barks, and M. alba fruits. The other test materials were ineffective. Because of its potent cytotoxic activity, the activity of each solvent fraction from the BFH was determined. Chloroform and ethyl acetate fractions showed the most potent cytotoxic activity. In conclusion, our results may be an indication of at least one of the pharmacological actions of B. mori feces. M. alba root barks, and M. alba fruits.