• 한국수자원학회논문집
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• 제37권6호
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• pp.461-466
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• 2004

본 연구에서는 쇄파대에서 정현파의 쇄파에 대해 수리모형실험과 수치모형실험을 수행하였으며, 두 실험결과를 비교하였다. 수치해석 모형에서는 Reynolds 방정식을 지배방정식으로 사용하고 난류해석을 위해 $textsc{k}$-$\varepsilon$ 모델을 적용하였으며, 자유수면변위를 추적하기 위해 VOF기법을 사용하였다. 수리모형실험과 수치모형실험 모두 동일한 수심과 주기를 가질 경우, 입사파의 파고가 커질수록 쇄파발생 지점이 경사시작 지점으로부터 가까운 위치로 이동하는 경향을 보였다. 또한, 쇄파발생시 파고비(H/H$_{0}$)는 동일한 수심과 파고를 가질 경우, 주기가 커질수록 증가하는 경향을 보였다.

• 한국환경농학회지
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• 제17권1호
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• pp.59-64
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• 1998

The environmental problem of the rural area has been accelerated in soil as well as water. Soil contamination is usually caused by improper operation of landfills, abandoned mine fields, accidental spills, and illegal dumpings. Once soil contamination is initiated, pollutants migrate and may cause groundwater contamination which takes much effort for remediation. Early detection, therefore, is important to prevent further contamination. Electrical resistivity method was used to detect soil contamination, but it was not effective to the heterogeneous condition. Static cone penetrometer test (CPT) has been used widely to investigate geotechnical properties of the underground. In this study, electrical resistivity method and CPT are combined to improve the applicability of it. The pilot test was performed to examine the variation of electrical resistivity with different soil minerals and pore fluid characteristics. Soil samples used were poorly graded sand, silty sandy soil, and weathered granite soil. For all the cases, electrical resistivity decreased with increasing of moisture content. Soil mineral also affected the electrical resistivity significantly. Above all, leachate addition in the pore fluid was very sensitive and caused decreasing of electrical resistivity markedly. It implies that electrical resistivity method can be applied to investigate pollutant plume effectively. This is specially sure when the sensors contact the contaminated soils directly. The CPT method involves cone penetration to the ground, therefore, underground contamination around the cone could be investigated effectively even for heterogeneous condition as it penetrates if electrical resistivity sensors are attached on the cone.

• 한국식품조리과학회지
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• 제24권1호
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• pp.59-67
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• 2008

In an effort to make a functional and stable yogurt, this study investigated the improvement effects of sea tangle extract and sea tangle yogurt on intestinal function. The intestinal improvement effect of the extract was measured by the charcoal meal transit method, employing Balb/C mice. And constipation relief was compared utilizing the loperamide-induced constipation method, employing SD rats. Charcoal meal transit was remarkably increased in the mice receiving sea tangle extract as compared to the controls. The constipation relief effects of the sea tangle and sea tangle yogurt were evaluated by measuring fecal amounts in the rats after adding them to water. The fecal contents increased remarkably in the sea tangle administered rat groups as compared to the control group. In addition, different yogurt samples were used to evaluate the characteristics of the sea tangle yogurt. During storage, pH slightly decreased in the yogurt with sea tangle as well as without. At the same time, acidity slowly increased as the storage duration increased. As time elapsed, the amounts of viable cells increased in both yogurts (with and without sea tangle). In the sensory evaluation, significant differences were shown between the sea tangle yogurt and the control for color, flavor, sweetness, and overall quality. Overall, based on the combined results of the intestinal function effects and sensory evaluation, the 0.25% sea tangle yogurt proved to be superior.

• 디지털융복합연구
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• 제15권12호
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• pp.615-623
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• 2017

본 연구는 중년 남성 근로자의 수면의 질에 미치는 영향 요인을 파악하기 위한 목적으로 시도된 서술적 조사연구이다. 본 연구의 대상자는 전남지역 사업장의 중년 남성 근로자 127명이며, 자료 조사는 구조화된 설문지를 이용한 자가 보고식으로 이루어졌다. 자료 분석은 t-test, one-way ANOVA, Pearson correlation coefficient 와 step wise multiple regression 으로 SPSS/WIN 18.0을 사용하여 분석하였다. 연구결과, 수면의 질과 관련 변인들 간의 관계를 살펴보면 직무 스트레스는 양의 상관관계를 보였고, 직무만족도는 음의 상관관계를 보였다. 직무스트레스 중 하위영역 직무요구, 직장문화와 직무만족 중 하위영역 직무자체가 수면의 질을 24.5% 설명하였다. 이에 중년 남성 근로자들의 수면의 질을 향상하기 위한 간호중재 전략과 직업만족도를 높이고 직업스트레스를 줄이는 전략을 강구해야 할 것이다. 더불어 대상자의 수면의 질 향상을 위해 과도한 업무량을 줄일 수 있는 제도적 방안 마련과 건전한 직장문화를 확립할 수 있도록 구성원 간의 노력이 필요할 것으로 생각된다.

• 한국환경과학회지
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• 제16권7호
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• pp.785-791
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• 2007

The current study evaluated the technical feasibility of the application of titanium dioxide ($TiO_{2}$) photo-catalytic air cleaners for the disinfection of bioaerosols present in indoor air. The evaluation included both laboratory and field tests and the tests of hydraulic diameter (HD) and lamp type (LT). Disinfection efficiency of photocatalytic oxidation (PCO) technique was estimated by survival ratio of bacteria or fungi calculated from the number of viable cells which form colonies on the nutrient agar plates. It was suggested that the reactor coating with $TiO_{2}$ did not enhance the adsorption of bioaerosols, and that the UV irradiation has certain extent of disinfection efficiency. The disinfection efficiency increased as HD decreased, most likely due to the decrease in the light intensity since the distance of the catalyst from the light source increased when increasing the HD. It was further suggested that the mass transfer effects were not as important as the light intensity effects on the PCO disinfection efficiency of bioaerosols. Germicidal lamp was superior to the black lamp for the disinfection of airborne bacteria and fungi, which is supported by the finding that the disinfection efficiencies were higher when the germicidal lamp was used compared to the black lamp in the laboratory test. These findings, combined with operational attributes such as a low pressure drop across the reactor and ambient temperature operation, can make the PCO reactor a possible tool in the effort to improve indoor bioaerosol levels.

• 한국유체기계학회 논문집
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• 제13권1호
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• pp.9-16
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• 2010

In the power generation industry, various efforts are needed to cope with tightening regulation on carbon dioxide emission. Integrated gasification combined cycle (IGCC) is a relatively environmentally friendly power generation method using coal. Moreover, pre-combustion $CO_2$ capture is possible in the IGCC system. Therefore, much effort is being made to develop advanced IGCC systems. However, removal of $CO_2$ prior to the gas turbine may affect the system performance and operation because the fuel flow, which is supplied to the gas turbine, is reduced in comparison with normal IGCC plants. This study predicts, through a parametric analysis, system performances of both an IGCC plant using normal syngas and a plant with $CO_2$ capture. Performance characteristics are compared and influence of $CO_2$ capture is discussed. By removing $CO_2$ from the syngas, the heating value of the fuel increases, and thus the required fuel flow to the gas turbine is reduced. The resulting reduction in turbine flow lowers the compressor pressure ratio, which alleviates the compressor surge problem. The performance of the bottoming cycle is not influenced much.

• Geomechanics and Engineering
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• 제20권3호
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• pp.191-205
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• 2020

Soil shear strength parameters play a remarkable role in designing geotechnical structures such as retaining wall and dam. This study puts an effort to propose two accurate and practical predictive models of soil shear strength parameters via hybrid artificial neural network (ANN)-based models namely genetic algorithm (GA)-ANN and particle swarm optimization (PSO)-ANN. To reach the aim of this study, a series of consolidated undrained Triaxial tests were conducted to survey inherent strength increase due to addition of polypropylene fibers to sandy soil. Fiber material with different lengths and percentages were considered to be mixed with sandy soil to evaluate cohesion (as one of shear strength parameter) values. The obtained results from laboratory tests showed that fiber percentage, fiber length, deviator stress and pore water pressure have a significant impact on cohesion values and due to that, these parameters were selected as model inputs. Many GA-ANN and PSO-ANN models were constructed based on the most effective parameters of these models. Based on the simulation results and the computed indices' values, it is observed that the developed GA-ANN model with training and testing coefficient of determination values of 0.957 and 0.950, respectively, performs better than the proposed PSO-ANN model giving coefficient of determination values of 0.938 and 0.943 for training and testing sets, respectively. Therefore, GA-ANN can provide a new applicable model to effectively predict cohesion of fiber-reinforced sandy soil.

• 한국통신학회논문지
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• 제28권9B호
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• pp.760-773
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• 2003

최선형 서비스에 기반을 둔 현재의 인터넷은 점차 새로운 멀티미디어 서비스 응용을 제공하기 위해 QoS를 보장하는 통합서비스 또는 차등화된 서비스 제공 형태로 잔화되어 가고 있다. 다가오는 시대의 멀티미디어 서비스별 QoS 요구 및 서비스별 높은 bandwidth 보장에 대한 요구는 IP/MPLS 기반의 제어 plane과 DWDM 광 네트워크 기술이 결합되어 미래의 re-configurable 전송망 실현에 대한 가장 설득력 있는 대안으로 떠오르고 있다. 본 논문에서는 이러한 차세대 DWDM 광 인터넷 백본망에서 멀티미디어 서비스 제공에 대한 QoS 보장을 위해 차등화된 MPLS 서비스(DMS)에 기반을 둔 차등화된 파장할당 과정을 제시한다. 또한 광 링크상의 파장 별 QoS 특성과 DWDM 차세대 인터넷 백본망 상에서 사용되는 OXC 노드의 종류에 따른 QoS recovery를 고려한 차등화된 파장할당 방안을 제시한다.

• Archives of Plastic Surgery
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• 제38권4호
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• pp.345-350
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• 2011

Purpose: Although platelet-rich plasma (PRP) potentiate the wound healing activity of adipose-derived stem cells (ADSCs), its effect cannot be sustained for a prolonged period of time due to short duration of action. This led us to design and produce platelet-rich fibrin (PRF), in an effort to develop a tool which lasts longer, and apply it on wound healing. Methods: Two symmetrical skin defects were made on the back of seven nude mice. ADSCs were applied to each wound, combined with either PRP or PRF. The wound area was measured over 14 days. By day 16, the wound was harvested and histologic analysis was performed including counting of the blood vessel. Results: The healing rate was more accelerated in PRP group in the first 5 days (p<0.05). However, PRF group surpassed PRP group after 6 days (p<0.05). The average number of blood vessels observed in the PRF group was $6.53{\pm}0.51$, compared with $5.68{\pm}0.71$ for the PRP group. Conclusion: PRF exerts a slow yet pervasive influence over the two-week course of the wound healing process. Thus, PRF is probably more beneficial for promoting the activity of ADSCs for a sustained period of time.

• 농업생명과학연구
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• 제46권4호
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• pp.101-111
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• 2012

콩 씨스트 선충은 콩 수량에 가장 심각한 피해를 입히는 선충이며, 콩 씨스트 선충으로 입는 피해가 연간 전 세계적으로 9백만 메가그램이나 되는 것으로 추정되고 있다. 콩 씨스트 선충은 식물 영양분을 먹어 뿌리의 성장을 지연시키고 근류균의 고정을 억제함으로서 수량의 감소를 가져 오게 된다. 콩 씨스트 선충을 방제하는 근본적인 방법은 저항성 품종을 재배하거나 윤작을 하는 것이다. 유전적으로 콩 씨스트 선충의 다양한 레이스들과 상업적 품종들의 제한된 저항성 품종들이 오랜 시간에 걸쳐 레이스 전환을 가져왔고, 이러한 이유로 콩 씨스트 선충의 방제가 매우 어려운 실정이다. 이 논문은 콩의 중요성, 콩 씨스트 선충, 콩 씨스트 선충 저항성에 대한 연구현황, 그리고 전망에 관해 고찰하였다.