• 동의생리병리학회지
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• 제25권2호
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• pp.189-194
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• 2011

Nardostachys chinensis (N. Chinensis) belonging to the family Valerianaceae have been used in traditional medicine to elicit stomachic and sedative effects. The present study investigated the effects of water extract of N. Chinensis in human lymphoma U937 cells. The proliferation of U937 cells was decreased by N. Chinensis. Anti-proliferative effect of N. Chinensis on U937 cells was associated with G0/G1 phase arrest, which was mediated by regulating the expression of p21 and p27 protein. In addition, the levels of CDK2, CDK4, CDK6, Cyclin D3, and Cyclin A were decreased, but Cyclin D1, Cyclin D2 and Cyclin E were essentially undetectable. N. Chinensis induced the differentiation of U937 as shown by increased expression of differentiation surface antigen CD11b, but not CD14. Taken together, these results demonstrated that N. Chinensis potently inhibits the proliferation of U937 cells via the G0/G1 phase cell cycle arrest in association with p21 and p27, and induces granulocytic differentiation.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.868-880
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• 2020

One of the main concerns in the structural integrity of offshore pipelines is mechanical damage from external loads. Pipelines are exposed to fatigue failure in welded joints due to geometric discontinuity. In addition, fatigue loads such as currents, waves, and platform motions may cause significant plastic deformation and fracture or leakage within a relatively low-cycle regime. The 2007 ASME Div. 2 Code adopts the master S―N curve for the fatigue evaluation of welded joints based on the mesh-insensitive structural stress. An extension to the master S―N curve was introduced to evaluate the low-cycle fatigue strength. This structural strain method uses the tensile properties of the material. However, the monotonic tensile properties have limitations in describing the material behavior above the elastic range because most engineering materials exhibit hardening or softening behavior under cyclic loads. The goal of this study is to extend the cyclic stress-strain behavior to the structural strain method. To this end, structural strain-based procedure was established while considering the cyclic stress-strain behavior and compared to the structural strain method with monotonic tensile properties. Finally, the improved prediction method was validated using fatigue test data from full-scale girth-welded pipes.

• 성인간호학회지
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• 제15권3호
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• pp.463-471
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• 2003

Purpose: This study was aimed at providing scientific evidence for minimizing ventilator-associated pneumonia(VAP) by identifying appropriate timing of exchange of circuit for mechanical ventilator that is well suitable for the medical environment of intensive care units of hospitals in Korea. Method: This was a quasi-experimental study with a convenience sample of 19 adult subjects aged over 18 years who were admitted to the NS ICU of C university hospital, and placed on mechanical ventilator. The subjects were placed in two groups, compared on the incidence rate of VAP after they received exchange of circuit either at 1-week interval (N =10) or 2-week interval (N = 9). Result: 1) When considering 1000 days as the standard unit of analysis for incidence, the incidence rate of VAP was 7.19 cases at the 1-week cycle exchange group and 15.23 at the 2-week cycle exchange group, showing no statistically significant difference between the two groups. 2) There were a total of 3 types of bacteria isolated from the patients with VAP, including 2 cases with P. aeruginosa, 1 case with Streptococcus group F and A. baumannii. Conclusion: With thorough hand washing and strict management of tracheal tube of mechanical ventilator as well as use of tracheal intubation techniques, exchange cycle of circuit of mechanical ventilator by nurses may be changed from 1-week to 2-week interval.

• 대한수학회논문집
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• 제11권4호
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• pp.1123-1135
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• 1996

In this paper, we introduce some properties of Steinhaus graphs of order n, and prove that the size of some special type of induced cycles in Steinhaus graphs of order n is bounded by $\left\lfloor \frac{n+3}{2} \right\rfloor$.

• 대한환경공학회지
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• 제34권2호
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• pp.86-90
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• 2012

아산화질소($N_2O$)는 온실효과가 $CO_2$의 300배 이상 되는 강력한 온실기체로서, 주로 탈질, 질산화와 같은 토양의 질소순환과정에서 생성되고 토양의 환경에 따라 복잡한 발생 양상을 보이는 것으로 알려져 있다. 본 연구는 하나의 유역 내에서 토지이용도에 따른 $N_2O$ 발생량의 변이와 이를 조절하는 요인을 밝히기 위한 목적으로 수행하였다. 이를 위해 강원도 해안 분지지형 내에 산림과 밭, 논 세 종류의 토지이용 형태를 선정하여, 2010년 5월부터 10월까지 매월 $N_2O$ 발생량을 측정하였다. 또한 계절 별 토양을 채취하여 무기질소의 함량을 비롯한 이화학적인 분석을 시행하였다. 그 결과 $N_2O$는 밭에서 많이 발생하였고, 이는 시비에 의한 질소의 유입 때문으로 분석되었다. 산림과 논 토양에서는 유기물로부터 유래한 무기질소가 존재하나, 그 공간적 편차가 크고 질소순환이 빠르게 진행되지 않아 $N_2O$ 발생량이 크지 않은 것으로 보인다. 토양의 $N_2O$ 발생량을 조절하기 위해서는 시비의 강도와 시점에 대한 관찰과 조절이 중요할 것으로 사료된다.

• 상하수도학회지
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• 제12권3호
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• pp.65-74
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• 1998

Life cycle assessment (LCA) on two different sludge treatment systems, on-site treatment and pipe-collected intensive treatment was performed to estimate the environmental impact in the aspect of global warming effect. As a main parameter of the estimation, $CO_2$ was chosen and quantified through the whole life cycle of the treatment systems including construction, operation and dismantlement. In this study, the changes of $CO_2$ production unit (CPU) by up-scaling n currently used sludge treatment processes were also calculated. As the result, a larger amount of $CO_2$ was exhausted from the construction step of intensive treatment system than that of on-site treatment system, because an additional pipe-collection system was needed in intensive treatment system. However, the total amount of $CO_2$ exhausted from whole life cycle including not only construction and dismantlement but also 15 year-operation and maintenance was reduced by appling intensive treatment.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.249-253
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• 2001

Neutron dose assessment in criticality accidents using Whole Body Counter (WBC) was proved to be an effective method as rapid neutron dose estimation at the JCO criticality accident in Tokai-mura. The 1.36MeV gamma-ray of $^{24}Na$ in a body can be detected easily by a germanium detector. The Minimum Detectable Activity (MDA) of $^{24}Na$ is approximately 50Bq for 10miniute measurement by the germanium-type whole body counter at JNC Tokai Works. Neutron energy spectra at the typical shielding conditions in criticality accidents were calculated and the conversion factor, whole body activity-to-organ mass weighted neutron absorbed dose, corresponding to each condition were determined. The conversion factor for uncollied fission spectrum is 7.7 $[(Bq^{24}Na/g^{23}Na)/mGy]$.

• 대한기계학회논문집
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• 제18권7호
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• pp.1664-1673
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• 1994

As a fundamental study on effects of thermal-cycles on residual stress of ceramics/metal joints, residual stresses in $Si_3N_4$/SUS304 joint specimens were measured before and single thermal-cycle by X-ray diffraction method and finite element method(FEM). The residual stress was found to increase after single thermal-cycle, which was agreeable with the results of residual stress measurement by X-ray diffraction method and residual stress analysis by finite element method. After the residual stress measurement, 4-point bending tests were performed. The relationship between the bending strength, the thermal-cycle temperature and hold time was examined. The bending strength was found to decrease with the increase of residual stress in linear relation.

• 한국컴퓨터정보학회논문지
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• 제21권2호
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• pp.97-103
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• 2016

This paper deals with the cycle time minimization problem that determines the productivity in printed circuit board (PCB) with n components using the m placement machines. This is known as production cycle time determination problem (PCTDP). The polynomial time algorithm to be obtain the optimal solution has been unknown yet, therefore this hard problem classified by NP-complete. This paper gets the initial assignment result with the machine has minimum unit placement time per each component firstly. Then, the balancing process with reallocation from overhead machine to underhead machine. Finally, we perform the swap optimization and get the optimal solution of cycle time $T^*$ within O(mn) computational complexity. For experimental data, the proposed algorithm can be obtain the same result as integer programming+branch-and-bound (IP+B&B) and B&B.

• Korean Journal of Mathematics
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• 제25권2호
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• pp.279-301
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• 2017

An L(3, 2, 1)-labeling for the graph G = (V, E) is an assignment f of a label to each vertices of G such that ${\mid}f(u)-f({\upsilon}){\mid}{\geq}4-k$ when $dist(u,{\upsilon})=k{\leq}3$. The L(3, 2, 1)-labeling number, denoted by ${\lambda}_{3,2,1}(G)$, for G is the smallest number N such that there is an L(3, 2, 1)-labeling for G with span N. In this paper, we compute the L(3, 2, 1)-labeling number ${\lambda}_{3,2,1}(G)$ when G is a cylindrical grid, which is the cartesian product $P_m{\Box}C_n$ of the path and the cycle, when $m{\geq}4$ and $n{\geq}138$. Especially when n is a multiple of 4, or m = 4 and n is a multiple of 6, then we have ${\lambda}_{3,2,1}(G)=11$. Otherwise ${\lambda}_{3,2,1}(G)=12$.