• 환경영향평가
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• 제29권5호
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• pp.323-337
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• 2020

국내 최대 상수원인 팔당호를 대상으로 기온과 수온의 변화를 살펴보고 장기간 기온과 수온의 연속 자료를 활용하여 이력 현상을 살펴보았다. 계절 Mann-Kendall을 적용한 팔당호 인근 양평의 기온 변화 추세는 지난 47년간(1973~2019) 증가(0.048 ℃/yr)에 비하여 최근 27년간(1993~2019) 기온의 증가(0.060 ℃/yr)가 컸다. 팔당호와 유입 하천에서 수온은 기온과의 상관성이 높으나(R > 0.9, p < 0.005) 호소인 팔당댐앞 지점에서의 수온은 하천 수온 상승에 비하여 느리고 기온 하강기에 들어서 수온이 서서히 감소하였고 수심 평균 수온도 상승기와 하강기 모두 호소 표층보다 변화가 더디게 나타났다. 이는 호소가 하천보다 수체 규모 면에서 크고 체류시간이 길기 때문에 열에너지를 흡수하고 감소하는데 시간이 걸리는 수온의 이력 현상이 크게 작용하는 것으로 판단된다.

• Reproductive and Developmental Biology
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• 제37권3호
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• pp.97-102
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• 2013

The objective of this study was to develop of semen transport system for cryopreservation and fertility in bull sperm. The ejaculated semen were diluted with Triladyl containing 20% egg-yolk for transportation. Diluted semen was transported by three methods that there were wrapping tissue (Tissue), sinking under $30^{\circ}C$ water (Water) and sinking between warm water and air (Air) methods. Semen was transported within 2 hours in $0.3^{\circ}C$. For this study, the freezing of diluted semen were added with Triladyl containing 20% egg-yolk. And frozen-thawed sperm were estimated with SYBR14/PI double stain for viability, FITC-PNA/PI double stain for acrosome reaction analysis and Rhodamine123 double stain for mitochondrial intact assessment. In results, live sperm (SYBR+/PI-) in Air treatment group ($43.3{\pm}4.7%$) was significantly (p<0.05) higher than other treatment groups (Tissue: $16.3{\pm}2.7%$ and Water: $27.5{\pm}3.1%$), dying sperm (SYBR+/PI+) in Air treatment group ($55.6{\pm}4.7%$) was significantly lower than other treatment groups (Tissue: $77.6{\pm}3.2%$ and Water: $67.6{\pm}3.3%$) (p<0.05). Acrosome reaction in Air treatment group ($0.2{\pm}0.1%$) within live sperm (PI negative region) was significantly (p<0.05) lower than other treatment groups (Tissue: $0.7{\pm}0.2%$ and Water: $0.5{\pm}0.1%$), the acrosome reaction in Air treatment group ($28.6{\pm}2.8%$) within all sperm also was significantly lower than other treatment groups (Tissue: $44.2{\pm}1.8%$ and Water: $36.2{\pm}2.0%$) (p<0.05). And mitochondrial intact in Air treatment group within live ($97.1{\pm}0.4%$) and all ($61.9{\pm}3.3%$) sperm were significantly higher than other treatment groups (Tissue: $85.2{\pm}3.3%$, Water: $87.8{\pm}2.9%$ within live sperm and Tissue: $49.28{\pm}3.7%$, Water: $42.0{\pm}3.1%$ within all sperm) (p<0.05). Therefore, we suggest that transportation by sinking method between warm water and air was beneficial to improvement of fertility in frozen-thawed in bull semen.

• 설비공학논문집
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• 제15권2호
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• pp.137-143
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• 2003

In the forming of an integrated system of radiant floor cooling and dehumidifying, chilled coil can be used for cooling and dehumidification. Therefore, it is necessary to find the efficient control method which can eliminates latent load efficiently. This study has been conducted to find this method by dividing the dehumidification system into 3 types according to the control variables and analyzing characteristics of each system. To prevent the floor surface condensation, the amount of condensation can be manipulated by water temperatures, water flow rates in chilled coil, and air flow rates passing by it. So dehumidification system control can be divided into constant air flow control and variable air flow control. Regarding dehumidification control, variable air flow control, which eliminates latent load rather than sensible load, is preferable to constant flow control.

• 한국안전학회지
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• 제35권6호
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• pp.85-92
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• 2020

Wet Scrubber reacts the incoming pollutant gas with cleaning water (water + absorbent) to absorb pollutants and release the clean air to the atmosphere. Wet scrubbers and packed tower scrubbers using this principle are widely used in businesses that emit acid gases. In particular, in the etching process using hydrochloric acid (HCl), alkaline washing water (NaOH) having a pH of about 8 to 11 is used to absorb a large amount of acid gas. However, These salts are attached to the injection nozzle (nozzle), filling material (packing), and the demister (Demister), causing air pollution, human damage, and inoperability due to clogging and acid gas discharge. Therefore, In this study, an improvement plan was proposed to manage the washing water with pH 3~4 acidic washing water. The test method takes samples from the Wet Scrubber flue measurement laboratory twice a month for 1 year. Hydrogen chloride (HCl) concentration (ppm) was measured, and nozzle clogging and scale conditions were measured, compared, and analyzed through a differential pressure gauge and a pressure gauge. As a result of the check, it was visually confirmed that the scale was reduced to 50% or less in the spray nozzle, filler, and demister. In addition, the emission limit of hydrogen chloride in accordance with the Enforcement Regulation of the Air Quality Conservation Act [Annex 8] met 3 ppm or less. Therefore, even if the washing water is operated in an acidic pH range of 3 to 4, it is expected to reduce air pollution and human damage due to clogging of internal parts, and it is expected to reduce maintenance costs such as regular cleaning or replacement of parts.

• Journal of Advanced Marine Engineering and Technology
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• 제34권5호
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• pp.743-749
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• 2010

자동 부침식 가두리 시설을 개발하기 위해 가두리 시설을 구형 부자로 단순화하여 이것의 자동 침하 및 상승 관련 제어 알고리즘 및 프로그램을 개발하였고 실내 수조 실험을 통해 그 유용성을 확인하였다. 또한 기존 연구 결과의 수치와도 비교 분석함으로써 기존 연구의 수치 모델 결과의 유용성을 재확인하게 되었다. 그리고 실물 실험에 대한 선행 연구로써 많은 변수들과 부력에 대한 비선형적인 메커니즘을 제어를 통해 극복하였으며, 이는 실물 실험에 있어 중요한 요소로 작용될 것이다.

• 한국산업융합학회 논문집
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• 제12권2호
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• pp.69-78
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• 2009

Dust in the fabric production sites is increased by the static electricity in air which is generated in the manufacturing process. The static electricity is shown in inverse proportion to humidity of the production sites. The optimum humidity rate for the filament in the production process has been established as 65~75%. Where as, average humidity rate of production site is estimated as 40%. Therefore, it is necessary to raise the humidity rate by 30% to maintain appropriate humidity to control generation of static electricity and dust in the production sites. In this study, a new air-jet water sprayer was developed and it can produce $10{\mu}m$ sprayed particles. When the air-jet water sprayer was operated on the production site dust generation rate was shown far below the environmental standard. It is assumed that when the air jet sprayers was applied to 1,000 fabric machines of 5 gloves making plants, its productivity and rates of operation will be improved by value of about 2.5 billion Won a year.

• 상하수도학회지
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• 제27권1호
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• pp.59-67
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• 2013

The odor occurring in the sewage system induces the displeasure, the disgust such as the headache, the vomit, etc. and increases the spiritual stress and disturbs the pleasant life of residents. These odors occur mainly in the area of combined sewage system treatment, being created in the personal sewage treatment plant such as septic tank and are incoming to sewage pipes and emitted to the outside through the manhole and the receiver, etc.; and this causes odors to the people. The Hydrogen Sulfide, the Methyl Mercaptan, the Ammonia, etc. are materials causing the odor, the more serious issue of odor is occurring since the septic tank of degradation process is being applied. The primary cause of odor is the decomposition of human feces in the septic tanks and sewage disposal facilities. The purpose of this study is reduction of hydrogen sulfide using air supplying and SOB(Sulfur-Oxidizing Bacteria). As a result of this study of the air supply system and the SOB media equipment by air supply, in case the air is injected to SOB media compared to the injection of air only, the removal efficiency the hydrogen sulfide was average 3.4 times higher.

• Corrosion Science and Technology
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• 제19권4호
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• pp.196-202
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• 2020

The air vent connected to a heat supply pipeline in the district heating system has been used to eliminate the existing air in the pipe, which has a detrimental effect on corrosion durability and heat efficiency. Recently, the air vent installed under a manhole for 22 years was corroded and several pinholes were detected in the front-end of the air vent. To identify the cause of the failure, thickness reduction, corrosion products, and water quality were examined. The corrosion damage was significant at the outside of the front-end of the air vent where the insulator was covered. While a thin oxide layer was formed in the interior of the tube, the coarse and porous corrosion products consisting of magnetite and hematite were found externally. Water flowing into the thermal insulator was absorbed by the insulator following hydrolysis. The hydrolyzed insulator ejected the corrosion factors such as Cl^-, SO₄^2-, and NH₄⁺. The findings suggest that the corrosion under insulation due to rain water is the main cause of the underlying failure in the air vent.

• 상하수도학회지
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• 제29권2호
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• pp.251-259
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• 2015

The main objective of this research is to study feasibility for applying metal membrane to remove particles from air scouring membrane backwash water. Also, the research was conducted to investigate the influence of polyamine coagulation on floc growth in membrane backwash water as pretreatment for removal particles. From the results of experiments for evaluating the influence of polyamine coagulation on floc growth, it was investigated that particles in the rage of $2{\sim}50{\mu}m$ grew up to $30{\sim}5,000{\mu}m$. In addition, all six metal membranes showed lower removal efficiency, which was 0.87~13.89%, in the case of no polyamine coagulant. On the other hand, in the case of injecting polyamine coagulant, those did extremely high efficiency in 56~92%. From the SEM(Scanning Electron Microscope) images of filtered wiremesh and metal foam membrane, sieve effects were predominant for liquid solid separation in wiremesh and adsorption and diffusion capture effects were predominant in metal foam membrane.

• 한국가시화정보학회지
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• 제15권2호
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• pp.59-67
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• 2017

To verify floatability of ABB (Air bubble barrier), we compared bubble swarm behavior with and without the air-driven ejector. Experiment was conducted using the fabricated air-driven ejector with 5 mm nozzle on the bottom of 1 m3 water tank. Reynolds number of air in the nozzle was ranged 1766-13248. We analyzed data with statistical method using image processing, particle mage velocimetry (PIV) and proper orthogonal decomposition (POD) analysis. As a result of POD analysis, there was no significant eigenmode in bubbly flow generated from the ejector. It means that more complex turbulent flows were formed by the ejector, thereby (1) making bubbles finer, (2) promoting three-dimensional energy transfer between bubble and water, and (3) making evenly distributed velocity profile of water. It is concluded that the air-driven ejector could enhance the performance of ABB.