• 한국해양학회지
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• 제29권1호
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• pp.17-27
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• 1994

한국심해연구(KODOS) 91-1지역에서 채취한 박스코어 퇴적물에 대해 미세립질 퇴적 물(2 um 이하)의 기원 및 각 광물의 분포경향과 미고생물 분석결과를 통해 퇴적환경 특성과 자생광물의 형성기작을 비교, 분석하였다. 점토광물에 대한 분석결과 퇴적물의 분포가 상대적으로 연령이 오래된 퇴적층(Unit II, III)으로 가면서 스멕타이트의 함 량은 증가하는 반면에 일라이트, 카오리나이트와 석영과 같은 육성기원퇴적물은 감소 하는 경향을 보였다. 또한, 미고생물에 대한 분석결과 상부퇴적층(Unit I과 Unit II상 부)에서는 제 3기와 제3기 방산층이 흔재되어 나타나는데 이는 퇴적물의 재동작용과 재분포가 매우 활발하였었다는 것을 의미하며, 퇴적층간에 산출되는 양상도 하부층으 로 가면서 퇴적물의 색도와 광물의 함량이 급격히 변화하는 뚜렷한 특징을 보여주고 있다. 퇴적층에 따른 퇴적물의 색도, 스텍타이트의 결정도와 미고생물자료를 비교한 결과 본 조사지역에서 나타나는 스멕타이트는 속성작용을 받아 형성된 자생기원의 광 물이 주로 분포하고 있음을 보여준다. 본 조사지역의 퇴적물에 나타나는 점토광물의 광물학적인 특성은 미고생물학적인 층서대비와 . 과거 지질시대를 통한 환경변이가 뚜 렷히 나타나며, 퇴적후 물리적인 기작과 지화학적인 영향에 의한 환경변화가 지속적으 로 활발하였음을 보여준다.

• 한국조경학회지
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• 제37권1호
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• pp.131-138
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• 2009

본 연구는 1962년부터 2007년까지 약 45년간 제정된 토목공사 표준품셈 공종에 속해 있는 조경공사 표준품셈을 대상으로 시대별 표준품셈의 변화의 흐름을 파악하여, 그 특성을 밝혀 향후 조경공사 표준품셈의 발전 방안에 대한 기초자료를 제시하고자 하였다. 연구의 결과는 다음과 같다. 조경공사 표준품셈이 속해 있는 공종 명칭과 관련해서 최초에는 '토공사'에서 1974년에 '토공 및 조경공사' 그리고 1984년에는 '조경공사'로 명칭이 개정되었으나, 현재까지도 조경공사 표준품셈은 토목공사 표준품셈에 조경공사라는 공종으로 되어 있다. 그리고 1972년에 조경공사와 관련해서 '식재'와 '전정작업' 품셈이 최초로 제정된 이후 현재는 '떼붙임 및 초류파종', '굴취', '식재', '뿌리돌림', '유지관리', '정원석 쌓기 및 놓기', '암 절개면 보호식재공' 등 총 7개 대공종과 29개 소공종으로 조경공사 표준품셈이 구성되어 있다. 시대별 특성을 10년 단위로 살펴보면 조경공사 표준품셈은 1960년대($1962{\sim}1969$)는 '잔디' 분야, 1970년대($1970{\sim}1979$)는 '수목식재' 분야, 1980년대($1980{\sim}1989$)는 '유지관리' 분야, 1990년대($1990{\sim}1909$)는 '절개면 보호' 분야 그리고 2000년대($2000{\sim}$현재)는 '신소재 및 신공법'과 '유지관리' 분야 위주로 조경공사 표준품셈이 제정되었다. 본 연구의 결과를 바탕으로 향후 조경공사 표준품셈의 발전 방안을 제시하여 보면, '신소재 및 신공법' 품셈의 제정과 '유지관리' 분야의 품셈들이 더욱 세분화된 방향으로 발전할 것으로 판단된다.

• 상하수도학회지
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• 제32권6호
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• pp.487-497
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• 2018

Water quality improvement processes for stagnant area consist mainly of technologies applying vegetation and artificial water circulation, and these existing technologies have some limits to handle pollution loads effectively. To improve the purification efficiency, eco-friendly technologies should be developed that can reinforce self-purification functions. In this study, a multi-functional floating island combined with physical chemical biological functions ((1) flotation and oxidization using microbubbles, (2) vegetation purification and (3) bio-filtration with improved adsorption capacity) has been developed and basic experiments were performed to determine the optimal combination conditions for each unit process. It has been shown that it is desirable to operate the microbubble unit process under conditions greater than $3.5kgf/cm^2$. In vegetation purification unit process, Yellow Iris (Iris pseudacorus) was suggested to be suitable considering water quality, landscape improvement and maintenance. When granular red-mud was applied to the bio-filtration unit process, it was found that T-P removal efficiency was good and its value was also stable for various linear velocity conditions. The appropriate thickness of filter media was suggested between 30 and 45 cm. In this study, the optimal design and operating parameters of the multi-functional floating island have been presented based on the results of the basic experiments of each unit process.

• 한국재료학회지
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• 제27권4호
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• pp.211-215
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• 2017

Reactive Ion Etching (RIE) and wet etching are employed in existing texturing processes to fabricate solar cells. Laser etching is used for particular purposes such as selective etching for grooves. However, such processes require a higher level of cost and longer processing time and those factors affect the unit cost of each process of fabricating solar cells. As a way to reduce the unit cost of this process of making solar cells, an atmospheric plasma source will be employed in this study for the texturing of crystalline silicon wafers. In this study, we produced the atmospheric plasma source and examined its basic properties. Then, using the prepared atmospheric plasma source, we performed the texturing process of crystalline silicon wafers. The results obtained from texturing processes employing the atmospheric plasma source and employing RIE were examined and compared with each other. The average reflectance of the specimens obtained from the atmospheric plasma texturing process was 7.88 %, while that of specimens obtained from the texturing process employing RIE was 8.04 %. Surface morphologies of textured wafers were examined and measured through Scanning Electron Microscopy (SEM) and similar shapes of reactive ion etched wafers were found. The Power Conversion Efficiencies (PCE) of the solar cells manufactured through each process were 16.97 % (atmospheric plasma texturing) and 16.29 % (RIE texturing).

• 한국물환경학회지
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• 제26권5호
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• pp.871-879
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• 2010

To figure out the removal efficiency of indicator and pathogenic bacteria by unit processes of a sewage treatment plant using activated sludge process, analyses were done for incoming sewage, influent and effluent of primary clarifier, aeration tank, secondary clarifier and final discharge conduit of the plant. A matrix of bacterial items (average of bacterial reduction [log/ml], p value of paired t-test, number of decreased cases of twenty analyses, removal percentage only for decreased cases) between incoming sewage and final effluent of the plant were heterotrophic plate counts (1.54, 0.000, 20, 95.01), total coliforms (1.38, 0.000, 19, 83.94), fecal coliforms (0.90, 0.000, 20, 94.84), fecal streptococci (0.90, 0.000, 20, 98.08), presumptive Salmonella (0.23, 0.561, 7, 99.09), and presumptive Shigella (1.02, 0.002, 15, 92.98). Total coliforms, fecal coliforms, heterotrophic plate counts, and fecal streptococci showed highest decrease through secondary clarifier about 1-log (p<0.001) between 88% and 96%, and primary clarifier represented the significant (p<0.05) decrease. However, final effluent through discharge conduit showed higher total coliforms and fecal streptococci than effluent of secondary clarifier (p<0.05). In addition, final effluent once violated the water quality standard while effluent of secondary clarifier satisfied the standard. Hence some control measures including elimination of deposits in discharge conduit or disinfection of final effluent are necessary.

• KSBB Journal
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• 제24권1호
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• pp.17-24
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• 2009

For the biosurfactant production process at first Candida bombicola, Sphingomonas yanoikuyae, Sphingomonas chungbukensis and Myxococcus flavescens were studied. As the most productive microorganisms C. bombicola, S. yanoikuyae and S. chungbukensis were selected. During many petrochemical industrial processes variable volatile organic componds are produced and they can cause an unpleasent and unhealthy atmosphere. Usually the volatile organic compounds are treated with chemical detergents. The chemical detergents cannot be easily degradable and can be accumulated in the nature. In this study we tried to develop a production process for the biosurfactants, which can substitute some chemical detergents in some chemical processes, with microorganisms. At second the treatment of the volatile organic compounds with the biosurfactants were tested and compared with the treatment with chemical detergent. The production productivities of the biosurfactant with microorganisms were compared. The growth patterns and kinetics of the microbial cells and the surface tension values of the biosurfactants were studied. The changes of the surface tension in variable pH conditions and sodium chloride concentrations were also studied. The volatile organic carbons were treated in a small plant scale. As the result of this study, it indicated that the specific growth rate of S. chungbukensis was the fastest by 0.144 ($hr^{-1}$). For surface tension, C. bombicola (38.1 dyne/cm) had the lowest value, and solubility of the volatile organic carbon was similar in C. bombicola and S. chungbukensis. (Toluene: about 0.1 Unit, Chloroform: about 0.6${\sim}$0.7 Unit, Benzene: about 0.5${\sim}$0.8 Unit). The biosurfactant, which were produced by C. bombicola, was selected for the further study for the volatile organic carbon treatment. With the biosurfactans from C. bombicola could remove the volatile organic carbon about 80% and this removal rate can be comparable with chemical detergent.

• 상하수도학회지
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• 제8권2호
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• pp.43-52
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• 1994

In this paper, the unit processes in the typical water treatment plant, which need to be expanded because the water demand is over the existing water treatment capacity in the near future, were carefully examined to upgrade the water treatment plant. The models were installed in the fields as a distorted model based upon the hydraulic similitudes. The models having the constant discharge ratio in the unit processes between the model and the prototype were installed as two units to compare the treatment efficiencies. The capacity of the individual unit, which is a model of the prototype of $250,000m^3/day$ capacity, was $24m^3/day$. In the mixing and flocculation experiments, the mixing intensity of flocculators G was selected as the main experimental item. The optimal mixing intensities G, which are 65/sec for experimental discharge of $1m^3/hr$ and 85/sec for experimental discharge of $1.3m^3/hr$, are identified based upon the comparison the relative turbidity removal efficiencies. Also, the outlet weir loading was selected as the main experimental item in the sedimentation process. Through the continuous experiments with the main experimental items of the mixing intensity of flocculators G and the outlet loading of the weir in the sedimentation basin, about 20% upgrading compared to the existing water treatment capacity was obtained.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.1937-1941
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• 2007

During a process of a nanoimprint for manufacturing LCD, a small temperature variation on the LCD glass can cause thermal stress and generate unexpected displacement. To avoid this trouble, a precision temperature control unit using thermoelectric modules is appropriate for nanoimprint processes. The unit consists of an air control system, a cooling water control system, and a power control system. The air control system includes a thermoelectric module, thermocouples measuring temperatures of air and a duct-stale fin, and two air fans. The heat generated by the thermoelectric module is absorbed by the cooling water control system. The power control system catches the temperature of the thermoelectric module, and a PID controller with SCR controls the input power of the thermoelectric module. Temperature control performance is evaluated by experiment and simulation. The temperature control unit is able to control the exit temperature about ${\pm}2^{\circ}C$ from the incoming fluid temperature, and the error range is ${\pm}0.1^{\circ}C$. However, the control time is approximately 30minute, which needs further study of active control

• 한국전산유체공학회지
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• 제16권4호
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• pp.110-115
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• 2011

A modern optical fiber manufacturing process requires the sufficient cooling of glass fibers freshly drawn from the heated and softened silica preform in the furnace, since the inadequately cooled glass fibers are known to cause improper polymer resin coating on the fiber surface and to adversely affect the product quality of optical fibers. In order to greatly enhance the fiber cooling effectiveness at increasingly high fiber drawing speed, it is necessary to use a dedicated glass fiber cooling unit with helium gas injection between glass fiber drawing and coating processes. The present numerical study features a series of three-dimensional flow and heat transfer computations on the cooling gas and the fast moving glass fiber to analyze the cooling performance of glass fiber cooling unit, in which the helium is supplied through the discretely located rectangular injection holes. The air entrainment into the cooling unit at the fiber inlet is also included in the computational model and it is found to be critical in determining the helium purity in the cooling gas and the cooling effectiveness on glass fiber. The effects of fiber drawing speed and helium injection rate on the helium purity decrease by air entrainment and the glass fiber cooling are also investigated and discussed.

• 한국산업융합학회 논문집
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• 제23권3호
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• pp.445-452
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• 2020

The air cleaning unit of K00 IFV(or Infantry Fighting Vehicle) has important roles to make sure the engine of the vehicle works precisely as filtering foreign substances in the air such as dust and sands. The entire components including scavenge fan which is one of the important inner part of the air cleaning unit are developed so that we can produce it domestically and don't need to import it from P^⁎⁎ Co., the original maker in United Kingdom. This paper introduces a few verification processes including cleaning efficiency and reliability. As this core unit has developed successfully the improvement of military strength and logistics support can be expected. And design capability, manufacturing skills, maintenance ability of tracked weapon system will be increased thanks to the accumulated technical knowledge obtained from this developing project. Foreign currency savings and reducing operational cost can be expected as well in military industry.