• 드라이브 ㆍ 컨트롤
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• 제19권1호
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• pp.8-15
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• 2022

The demand for the re-painting of steel bridges is increasing, but surface treatment is still centered on human resources for on-site re-painting processes. Worker safety accidents continue to occur because the work is performed in a narrow space. Recently, PS balls with excellent surface treatment have been used for blasting, but the working environment is poor due to the large amount of dust generated. In this study, an effective surface treatment method using impeller blasting equipment was developed. The correlation between steel ball size, impeller rotation speed, and exposure time was studied to optimize the efficiency of the surface treatment.

• 한국물환경학회지
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• 제25권2호
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• pp.268-280
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• 2009

Oncheon basin which are located in Busan is divided into 43 basin on the basis of main pipe, constructed with Storm Water Management Model (SWMM). Occurrence situation for Outflow and pollutant loads by long-term continuous rainfall is examined for treatment district and river analysis point of Oncheon basin and a reduction vs effectiveness table for effective CSOs managements is made for each of treatment districts according to each of managements. In case that treatment equipment is located at the discharge point of CSO, treatment efficiency is analysed. It is supposed that treatment equipment have an efficiency on the basis of a concentration and runoff discharge over a critical flow is discharged with it untreated and treating runoff discharge with treatment equipment at each of runoff discharge points and treating it gathered at sewage treatment plant (STP) through trunk sewer is compared for a relative treatment efficiency.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2018년도 공동국제학술발표회
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• pp.164-164
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• 2018

• 한국군사과학기술학회지
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• 제24권2호
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• pp.197-203
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• 2021

Mechanical structures of military equipment have been mainly applied with black oxide coating due to the limitation of surface treatment thickness. However, the mechanical structures applied by the black oxide coating treatment is constantly being corroded by calcium chloride and humidity. Since this can cause serious problems in the operation of equipment, a review to improve surface treatment and corrosion resistance is required. Therefore, in this study, surface treatment methods that can enhance corrosion resistance were selected and corrosion resistance performance was verified through experiments describing harsh field conditions. Thus, applying a proven surface treatment method to future military equipment will prevent corrosion.

• Journal of Ecology and Environment
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• 제38권3호
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• pp.293-305
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• 2015

In order to understand the mechanisms of conversion between different algal dominance, an experiment was performed in a greenhouse from 22 June to 10 July 2011. The experiment included a treatment group subjected to three instances of nutrient enrichment and a control with no nutrient enrichment. The initial water was dominated by Ankistrodesmus of Chlorophyta. The average water temperature at 08:30 h and 14:00 h during the experiment was $31.6^{\circ}C$ and $34.6^{\circ}C$, respectively. The results showed that the total nitrogen (TN), total phosphorus (TP), dissolved total nitrogen (DTN), dissolved total phosphorus (DTP), and soluble reactive phosphorus (SRP) concentrations in the treatment were significantly higher than in the control (P < 0.05). However, the TN/TP and DTN/DTP in the control was higher than in the treatment (P < 0.05). The dominant algae in the control did not change during the experiment, while the dominant algae in the treatment switched to Planktothrix of Cyanophyta on day 9. The chlorophyll a (Chl-a), wet weight of all algae, wet weight of Cyanophyta, and percentage of Cyanophyta in the control were all significantly lower than in the treatment (P < 0.05). Amounts of zooplankton, especially rotifers, were present at the end of the experimental period. The density of rotifers between the control and treatment was not significantly different (P > 0.05), while the copepod density in the treatment was higher than in the control (P < 0.05). We conclude that green algae dominance quickly switches to cyanobacteria dominance after nutrient enrichment in a greenhouse with elevated temperature.

• 한국의학물리학회지:의학물리
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• 제4권1호
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• pp.23-28
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• 1993

치료계획을 수행하는데 수반되는 isodose planning system 과 isodose calculation system, data set, equipment 등에 관한 치료계획의 성능관리에 대한 고찰을 시도하여 치료 오차의 한계를 최소화하여 치료행위의 정확성을 기하고자 한다.

• 대한환경공학회지
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• 제35권11호
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• pp.763-768
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• 2013

본 논문에서는 하수처리장 주요 장비 고장밀도함수를 기반으로 시스템 가용성 평가가 수행되었다. 프로세스 구성과 구성요소의 고장률에 따른 시스템 가용성 및 위험요소 분석에 초점을 맞추고 있다. 하수처리장 시스템 가용성 분석을 위하여 기자재 분류와 해당기자재의 고장확률밀도함수를 정립하였다. 가용성 평가 과정의 불확실성의 해소를 위하여 몬테카를로 시뮬레이션 기법과 이벤트기법을 도입하였다. 하수처리장 시스템 가용성은 구성장비가 직렬연결 상태인 경우에 50.4%로 평가되었으며, 장비별 보조시스템이 추가 적용된 경우 80.1% 이상으로 증가하였다. 슬러지 탈수 및 농축 공정의 시스템 오작동은 전체 시스템 오작동의 77% 이상에 해당하고 있어 주 위험 요인으로 평가되었다.

• 열처리공학회지
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• 제36권2호
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• pp.86-95
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• 2023

This paper explained the equipment and process development to secure the source technology of controlled nitrification technology. The nitriding potential in the furnace was controlled only by adjusting the flow rate of ammonia gas introduced into the furnace. In addition, a control system was introduced to automate the nitriding process. The equipment's hardware was designed to enable controlled nitriding based on the conventional gas nitriding furnace, and an automation device was attached. As a result of measuring the temperature and quality uniformity for the equipment, the temperature and compound uniformity were ±1.2℃ and 14.3 ± 0.2 ㎛, respectively. And, it was confirmed that nitriding potential was controlled within the tolerance range of AMS2759-10B standard. In addition to parts for controlled nitriding, it was applied to products produced in existing conventional nitriding furnaces, and as a result, gas consumption was reduced by up to 80%.

• International Journal of Ocean System Engineering
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• 제2권4호
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• pp.209-213
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• 2012

Recently, the fuel using in the diesel engines of marine ships has been changed to a low quality of heavy oil because of the steady increase in the price of oil. Therefore, the wear and corrosion in all parts of the engine such as the cylinder liner, piston crown, and spindle and seat ring of exhaust valves has correspondingly increased. The repair welding of a piston crown is a unique method for prolonging its lifetime from an economic point of view. In this case, filler metals with a high corrosion and wear resistance are mainly being used for repair welding. However, often at a job site on a ship, a piston crown is actually welded with mild filler metals. Therefore, in this study, mild filler metals such as CSF350H, E8000B2, and 435 were welded to SS401 steel as the base metal, and the corrosion properties of the weld metals with and without post weld heat treatment were investigated using some electrochemical methods in a 0.1% $H_2SO_4$ solution. The weld metal welded with CSF350H filler metal exhibited the best corrosion resistance among these filler metals, irrespective of the heat treatment. However, the weld metal zones of the E8000B2 and 435 filler metals exhibited better and worse corrosion resistance with the heat treatment, respectively. As a result, it is suggested that in the case of repair welding with CSF350H and 435 filler metals, no heat treatment is advisable, while heat treatment is desirable if E8000B2filler metal is used with repair welding.

• International journal of advanced smart convergence
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• 제9권1호
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• pp.19-28
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• 2020

We studied the on-site treatment of soil contaminated by heavy metals and petroleum was tested using relocatable soil washing equipment for greater remediation efficiency. Different combinations of pH and solid/liquid ratio were tested to determine the optimum balance, settling on values of 5 and 1:2, respectively. Next, soils containing Pb, Hg, and petroleum were further tested to assess the optimum number of washing cycles. The remediation efficiency of Pb and Hg in soil contaminated solely by heavy metals was 90.1% and 86.4% after three and two washings, respectively. The remediation efficiency of petroleum in soil contaminated solely by petroleum was 98.8% after one washing. When soil contaminated by both heavy metals and petroleum was cleaned, up to 91.0% of Pb, 86.9% of Hg, and 96.1% of petroleum was removed after two, one, and one washings, respectively. We conducted all remediation efficiencies and concentration reductions satisfied the standard threshold for soil contamination in South Korea.