• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1224-1228
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• 2005

본 연구는 강우시 주로 발생되는 강우유출수에 의해 하천으로 직유입 되는 다량의 오염물질을 사전에 저감시키기 위하여 하천의 제방사면부와 둔치부를 형상화한 Pilot 규모의 수처리시스템에 관한 것이다. 본 Pilot Plant는 경희대학교 내 하수처리장 부근에 설치하였으며, 유입부, 사면수처리부, 평면수처리부, 유출부로 구성되며, 수처리조 내부에 다공성여재와 상부에는 식생을 조성하여 연속적으로 운영되는 시스템으로 설계되었다. 사면수처리부는 하천의 제방사면부를 형상화 한 것으로 2:1의 구배를 가지며, 15개의 육각형 모듈을 5개씩 3계열로 배치하여 여재의 처리효율 및 현장 적용성 검토를 실시할 수 있도록 배열하였다. 평면수처리부는 장방형의 접촉산화조로서 하부에 슬러지 침전 및 저류를 위한 hopper를 설치하여 슬러지의 원활한 수집 및 인발이 가능하도록 설계하였다. 또한, 역세를 위한 배관을 설치하여 여재에 부착된 슬러지의 양 조절이 가능하도록 하였다. 또한, 수처리시설물의 자연 친화성 확보 및 식생에 의한 수질개선 효과를 위해 수처리부 상부에 식생을 조성하였다. 본 Pilot Plant의 주요 오염물질의 제거기작은 수처리부 내부에 충진된 다공성 여재와 강우유출수 사이에 발생되는 침전, 여과, 흡착과 여재에 부착된 미생물에 의한 유기물 분해, 식생에 의한 영양물질 섭취 등으로 대별된다. 본 연구는 하천의 제방사면부와 둔치부를 형성화한 Pilot Plant에서 다양한 factor, 즉 유입수량과 농도, 다공성여재 형상 및 충진밀도 등에 따른 수질개선 효과를 각각 비교, 검토하였다.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.631-638
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• 2016

Offshore wind power can be an alternative for onshore wind power which suffers from not only civil complaints regarding to landscape damage and noise but also wind power siting due to lack of onshore site candidates. Compared to onshore wind power, offshore wind power is free from these problems considering that generally the sites are far enough from the coast. And more electricity is generated in offshore wind turbines due to abundant offshore wind resources. However high installation costs of offshore turbines could deteriorate the economical efficiency. The main cause of the high installation costs comes from a long-term lease of the heavy marine equipment and the consequential high rental cost. In this paper, the conceptual design of the support structure for offshore wind turbines will be suggested for the installation of them with less heavy marine equipment.

• Analytical Science and Technology
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• v.26 no.5
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• pp.299-306
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• 2013

Pyroligneous liquor as a byproduct from charcoal production of bamboo sprout produced damyang-gun has the broad benefits such as improvement of soil quality, plant growth control and is mainly used for the treatment of atopic dermatitis, fungi and many other skin diseases. In this study, flavor compounds of pyroligneous liquor from bamboo sprout produced in Damyang-gun were analyzed and compared using three different methods including direct analysis (DA), headspace solid phase microextraction (HS-SPME) and stir bar sorptive extraction (SBSE). Simultaneously, the analytical conditions of GC-MS for the determination of volatile compounds were optimized. Based on volatile organic compounds detected by GC-MS, SBSE and SPME methods showed higher sensitivity than direct analysis. Major compounds of pyroligneous liquor were cresol, guaiacol, p-ethyl guaiacol and syringol. These phenolic compounds are reported as the useful chemicals with medicinal activity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2313-2321
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• 2014

A concentration meter is widely used at purification plants, sewage treatment plants and waste water treatment plants to sort and transfer high concentration sludge and to control the amount of chemical input. This study has been prepared for improving efficiency of operation on sludge processes and to establish a basic for factory automation by accuracy improvement and problem solution of sludge concentration meter. The concentration meter's accuracy and stability is improved by applying multi-beam sensors and minimum deviation linear average filtering. Furthermore maintenance without cut-off of water in sludge operation is possible by detachable sensors. The performance of multi-beam concentration meter has been variously verified by the pilot plant experiment.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.835-844
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• 2019

This study dealt with a systematic approach for sediment replenishment works which defines the artificial supply of coarse sediment to downstream river channels of dams. That is an increasing practice in Japanese, American and European rivers for the purpose of compensating sediment deficits downstream and rehabilitating geomorphological habitats below dams. We introduced five main objectives of the sediment replenishment, simply from construction of artificial spawning redds for anadromous fish to restoration of fluvial geomorphological process of river system. Then we suggested determination of sediment size distribution and quantity of coarse sediment as well as selecting an effective implementation method in corresponding to specific objectives and local restrictions in the basin, reservoir and river.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.437-446
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• 2006

A fabrication method fur high-aspect-ratio microchannels in stainless steel using laser-assisted thermochemical wet etching is reported in this paper. The fabrication of deep microchannels with an aspect ratio over ten is realized by applying a multiple etching process with an optimization of process conditions. The cross-sectional profile of the microchannels can be adjusted between rectangular and triangular shapes by properly controlling laser power and etchant concentration. Excellent dimensional uniformity is achieved among the channels with little heat-affected area. Microchannels with a width ranging from 15 to $50{\mu}m$ can be fabricated with an aspect ratio of ten and a pitch of 150 m or smaller. The effects of process variables such as laser power, scan speed, and etchant concentration on the fabrication results, including etch width, depth, and cross-sectional profile are closely examined.

• Journal of the Korea Society of Computer and Information
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• v.28 no.3
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• pp.101-110
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• 2023

This study was conducted to identify factors influencing weight loss efforts in hypertensive patients with obesity in Korea using data from the 2016-2019 National Health and Nutrition Examination Survey. Weight perception, weight loss efforts, and weight control methods were investigated for 1,910 subjects. Data were analyzed using descriptive analysis, cross-tabulation analysis and logistic regression. Among obese hypertensive patients, 12.6% perceived their weight as normal. Weight loss efforts were 2.03 times (95% CI: 1.48 to 2.78) higher in people with overweight perception than those with normal weight perception, and 1.74 times (95% CI: 1.33 to 2.26) higher in women than in men. In addition, those with class 1 obesity were 1.50 times (95% CI: 0.85 to 2.65) higher than those with class 3 obesity, and those with class 2 obesity were 2.16 times (95% CI: 1.16 to 4.00) higher than those with class 3 obesity. These results suggest that weight management approaches for hypertensive patients with obesity should be individually designed according to weight perception, gender, and obesity class.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.94-94
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• 2022

본류와 지류가 만나는 하천 합류부에서 발생하는 복잡한 흐름 구조는 하상변동에 영향을 주며, 본류와 다른 특성을 보이는 지류의 유입은 수질과 수생태계에도 영향을 준다. 합류부는 하천 변화의 다양성을 보이기 때문에 하천 관리 측면에서 중요한 구간으로, 흐름 및 혼합 특성 이해가 중요하다. 합류부에서의 흐름 및 혼합은 본류와 지류의 유량비, 밀도차, 단차, 합류각, 하도형상 등의 영향으로 그 양상이 달라지며, 흐름장 및 두 수체에 의한 이송물질의 혼합이 이루어졌다고 간주하는 혼합거리는 지류가 본류에 미치는 영향 범위 분석을 위한 중요한 매개변수이다. 본 연구에서는 합류부 흐름에 미치는 주요 인자 중 유량비와 밀도차가 합류부 흐름 및 혼합에 미치는 영향을 수치해석을 통해 분석하고, 조건의 변화에 따른 혼합거리를 예측해 보고자 한다. 본 연구의 대상 지역인 낙동강-황강 합류부는 다기능보와 댐의 운영에 따라 유입 유량 및 유량비가 조절되며, 여름철에는 황강의 수온이 낙동강보다 평균 4℃ 이상 낮으며, 9℃(지류 20℃; 본류 29℃) 이상의 수온차가 발생하기도 한다. 이 경우 밀도비는 0.998로 밀도류가 발생할 수 있는데, 밀도류가 발생할 경우 수표면과 저층이 분리되어 흐르기 때문에 동일 유량 조건에서도 혼합 양상은 달라진다. 밀도류가 발생하기 위해서는 수표면과 저층이 분리되는 성층이 발달해야 하는데, 이는 유속 또는 유량의 범위에 따라 성층의 발달 여부가 달라질 수 있다. 이러한 현장 조건을 반영한 수치해석을 통해 다양한 유량 조건(유량비)에서 밀도의 차이(수온차)가 합류부의 흐름 및 혼합에 미치는 영향을 분석해 보고자 하며, 합류부에서 밀도차에 의한 흐름의 변화 조건을 무차원수(Richardson number, Densimetric Froude number 등)를 통해 정량화해보고자 한다. 이는 지류가 본류에 미치는 영향의 정도와 범위를 파악함으로써 하천 관리를 위한 관측망 및 현장 조사의 범위 선정의 기초자료 마련뿐 아니라 본류의 수온 변화가 발생할 수 있는 범위의 파악을 통해 수생태계에 미치는 영향 파악을 위한 기초자료로 활용될 수 있을 것으로 기대된다.

• Composites Research
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• v.36 no.5
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• pp.310-314
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• 2023

VaRTM(Vacuum assisted resin transfer molding) and VAP(Vacuum assisted process) processes are a type of RTM(Resin transfer molding) process, and are typical out-of-autoclave (OOA) processes that can manufacture large structures at low cost. In this paper, a resin filling test was conducted to compare the VaRTM and VAP processes, and the filling process and dimensional stability were compared. In addition, an analysis method to simulate the filling process was developed, and a dielectric sensor was used to detect the flow front of the resin, which was compared with the analysis results. From the resin filling test, the total filling time of the composite plate was measured to be 48 minutes for the VAP process and 145 minutes for the VaRTM process, and the filling time by the VAP process was reduced by about 67%. In addition, it was confirmed that the VAP process was superior to the VaRTM process in the thickness control ability and uniformity of the composite plate.

• Journal of the Korea Concrete Institute
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• v.25 no.3
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• pp.321-329
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• 2013

Recently, the medium-low level radioactive waste from nuclear power plant must be transported from temporary storage to the final repository. Medium-low level radioactive waste, which is composed mainly of the liquid ion exchange resin, has been consolidated with cementitious material in the plastic or iron container. Since cementitious material is brittle, it would generate cracks by impact load during transportation, signifying leakage of radioactive ray. In order to design the safety transporting equipment, there is a need to check the compressive strength of the current waste. However, because it is impossible to measure strength by direct method due to leakage of radioactive ray, we will estimate the strength indirectly by the dynamic modulus of elasticity. Therefore, it must be identified the relationship between of strength and dynamic modulus of elasticity. According to the waste acceptance criteria, the compressive strength of cement based solid is defined as more than 3.44 MPa (500 psi). Compressive strength of the present solid is likely to be significantly higher than this baseline because of continuous hydration of cement during long period. On this background, we have tried to produce the specimens of the 28 day's compressive strength of 3 to 30 MPa having the same material composition as the solid product for the medium-low level radioactive waste, and analyze the relationship between the strength and the dynamic modulus of elasticity. By controling the addition rates of AE agent, we made the mixture containing the ion exchange resin and showing the target compressive strength (3~30 MPa). The dynamic modulus of elasticity of this mixtures is 4.1~10.2 GPa, about 20 GPa lower in the equivalent compressive strength level than that of ordinary concrete, and increasing the discrepancy according to increase strength. The compressive strength and the dynamic modulus of elasticity show the liner relationship.