In this paper, internal and external flow analysis of nozzle for a automatic bike washing machine was performed using Ansys Fluent, by varying nozzle injection pressure and angle. The pressure and velocity distributions generated at the nozzle outlet from internal flow analysis were applied for inlet condition of the external flow analysis of the nozzle. As a criterion for the cleaning efficiency, the shear stress condition provided by EHEDG[5] was used and an area of shear stress of 3 Pa or more according to the spray angle and pressure was compared. It is expected that the results of this paper will be applied to the development of automatic contactless bike washing nozzle.

Due to global climate change, Korea is experiencing flooding and drought severely. It is hard to manage water resources because intensive precipitation during short periods and drought are commonly occurred in Korea, recently. Severe drought occurred in 2015 and 2017 in the islands, and coastal and inland areas in Korea, and the citizens experienced decreased water supply and emergency water service by using bottled water. Therefore, the Korean government provided additional governmental funds such as the grant of drought disaster. In this study, we tried to calculate the cost of water for drought response based on the cost of tap water for the regional local governments in Korea and the grant of drought disaster by the Ministry of the Interior and Safety in Korea, etc. The estimated costs of water for drought responses in coastal and inland areas which have a chance to apply alternative water sources such as brackish or seawater desalination and water reuse in Korea were higher than in other areas in Korea. Additionally, as the novel approach of drought response, the 300 m3/day-scale desalination vessel was suggested to provide desalinated water for the islands in Korea. The estimated expenses of water supply for the target island areas (Sinan-gun and Jindo-gun) by the desalination vessel was lower than those by emergency water service by using bottled water.

With growing expectations for economic cooperation between the two Koreas, there is much interest in participating in the construction of infrastructure in North Korea. In particular, water and sewage infrastructure is the four major social infrastructures in addition to housing, transportation, electricity and telecommunications. North Korea is known to have severe water pollution and ecosystem destruction in major rivers, water pollution and soil pollution in mining areas are serious, and water and sewage infrastructures in cities other than Pyongyang are known to be weak. Preemptive investment in water supply and drainage in North Korea is the foundation for securing the quality of life of the North Korean and is the foundation of public health and industry. It is a leading investment to reduce the cost of unification and is a new growth engine for the water reloded industry. In this study, we proposed a plan to exchange and cooperate in water environment for building water infrastructure of North Korea by examining the data related to water quality, water resources, water disaster, related legal system and human resources exchange situations in North Korea.

A two-phase flow in mini-channels is consist with various flow regimes (such as bubble slug, annular, churn flow) according to gas and liquid phase flow rates. A previous researches revealed that in a case of slug flow in hydrophobic mini-channels, gas and liquid phase are perfectly separated by interfaces and triple contact line. In this study, the single dry slug flow experiments in circular mini-channel (D = 1.018 mm) are conducted to observe interfacial break-up phenomena in high capillary number range (Ca < 0.02). The slug is consist with D.I. water or D.I. water-ethanol binary mixtures (5% and 10%, mole fraction). On the base of previous researches, we calculate the pressure drop at moving triple contact line. In an addition, a single dry slug flow is visualized by using high-speed camera. Through the experiment, three regimes of pressure drop are observed; steady, loss, separation. As a result, criteria between steady and loss regimes is closely related to capillary number, and criteria between loss and separation regimes is related to surface tension.

When oil spill disaster on sea takes place, the most effective measure is to use oil fence with vertical wall. It has been big challenges that suitable oil fence in consideration of variety of variables such as wind speed, height of wave and current direction is chosen. And current characteristics below two of vertical wall was studied by PIV experiment with utilizing technic of visualized analysis like velocity distribution, contour of velocity and streamline pattern in flow characteristic between vertical wall of oil fence. In this study it is purposed to identify characteristics of inside water flow between two vertical walls depending on respective various water speeds to minimize outflow of floating article below bottom of vertical wall and observed that re-circulation flow and irregular vortex at certain places between two vertical walls occurred. Consequently, the study showed that failure of oil fence such as entrainment failure and submergence failure can be largely lessen by means of optimizing length between two vertical walls with water speeds.

야생 잎새버섯 추출물을 이용하여 심혈관계 질환과 관련된 기능성 식품 개발을 위한 기초자료를 얻기 위해 준비한 물 추출물과 유기용매 분획물의 혈전용해활성과 트롬빈저해활성, acetylcholinesterase 저해활성, 항산화활성을 확인하였다. 10 mg/mL의 농도에서 물 추출물과 물 분획물은 각각 0.93 plasmin unit와 0.73 plasmin unit의 높은 혈전용해활성을 나타냈으며, 부탄올 분획물은 79.60%의 트롬빈저해활성을 나타냈다. 클로로포름 분획물은 85.88%의 높은 acetylcholinesterase 저해활성을 나타냈고, 물 추출물의 항산화 활성은 39.81%로 비교적 낮게 나타 냈다. 부분 정제된 효소를 포함하고 있는 물 분획물은 섬유소원의 Bβ chain를 모두 분해시켰지만, Aα chain은 느리게 분해시키고 γ chain 과는 반응하지 않았다. 실험 결과로부터 야생 잎새버섯 추출물은 높은 혈전용해활성과, 트롬빈저해활성, acetylcholinesterase 저해활성을 나타내 심혈관계 질환 예방을 위한 제약과 기능성식품 개발에 이용 가능할 것으로 기대된다.

This research proposes an optimal flushing operation technique in an effort to prevent secondary water pollutions and accidents in aged pipes, and to improve the cleaning effect of unidirectional flushing. Water flow directions were analyzed using EPANET 2.0, while flushing and air scouring experiments in forward and reverse directions were performed in the field. In 42 experiments, average residual chlorine concentration and turbidity were improved after cleaning compared to before cleaning. It was found that even when the same cleaning method was used, further improvement of cleaning effect was possible by applying air injection and reverse direction cleaning techniques. By means of one-way ANOVA(Analysis of variance), it was also possible to statistically verify the need of actively utilizing air injection and reverse direction cleaning. Based on correlation between turbidity and TSS, the total amount of suspended solids removal was estimated for 874 flushing operations and 194 air scouring operations. The result showed that air scouring used more discharge water than flushing by an average of 4.9 m3 yet with larger amounts of suspended solids removal by an average of 145.9 g. The result of analysis on turbidity values from 887 flushing operations showed low cleaning effect of unidirectional flushing for the pipes with diameters over 300 mm. In addition, the turbidity values measured during cleaning showed an increasing tendency as pipe age increased. The methodology and results of this research are expected to contribute to the efficient maintenance and improvement of water quality in water distribution networks. Follow-up research involving the measurement of water quality at regular time intervals during cleaning would allow a more accurate comparison of discharge water quality characteristics and cleaning effects between different cleaning methods. To this end, it is considered necessary to develop a standardized manual that can be used in the field and to provide relevant trainings.

본 연구에서는 종결정 크기, 종결정 코팅양, 수열 용액 숙성시간을 조절함으로써 분리층 두께가 제어된 모데나이트 제올라이트 분리막을 제조하고, 분리층 두께가 투과증발 물 투과유속에 미치는 영향을 90 wt.% 에탄올 수용액에서 고찰 하였다. 유성 밀을 이용해 종결정을 분쇄시켜 20~30 nm 크기의 종결정을 제조하였고, 진공여과코팅 중에 종결정 용액의 농도와 통과된 양을 바꿔주면서 코팅양을 조절하였다. 제조된 분리막은 분리층 두께가 얇을수록 더 높은 물 투과유속을 나타내었으며, 약 4 μm 두께를 갖는 분리막의 경우, 760의 높은 물/에탄올 선택도와 1.0 kg/m2h의 높은 물 투과유속을 나타내었다. 이는 나노크기 종결정을 사용하여 4 μm 두께로 분리층을 얇게 만들었기 때문으로 판단된다. 따라서 본 연구로부터 종결정의 크기와 진공여과 코팅양, 수열 용액 숙성시간을 조절하는 것은 분리 층의 두께를 효과적으로 조절할 수 있는 방법임을 알았 다. 또한, 모데나이트 제올라이트 분리층의 두께를 얇게 하는 것이 분리막의 물 투과유속을 증진시키는 중요한 방법임을 확인 하였다.

At a two phase flow, according to gas and liquid phase flow rates, various flow regimes are developed such as bubbly, slug/plug, churn, annular, droplet flow and so on. At a two phase flow in small scaled channels, among various flow regimes, the intermittent flows such as bubbly, slug/plug flow are developed in the broad regions of two phase flow pattern map. In particular, the flow regimes are influenced by surface wettability. In a case of slug flow in hydrophobic small scaled channels, gas and liquid phases are perfectively separated by interfaces and contact line. The pressure drop of the two-phase flow is largely generated at moving contact line. Therefore, to well design two-phase flow system with small scales, it is important to estimate the pressure drop at moving contact line. In this study, on the basis of previous research, the pressure drop at moving contact line is experimentally measured for a various fluids (0-40% water-ethanol mixtures). And, the previous correlation to estimate pressure drop at moving contact line is verified by experimental data. In an addition, we discuss interfacial broken phenomena of slug flow in a minichannel. (D=1.555mm).

One of the most effective methods to consistently ensure the safety of a tap water supply can be achieved by application of a comprehensive risk assessment and risk management approach for drinking water supply systems. This approach can be termed water safety plans(WSP) which recommended by WHO(world health organization) and IWA(international water association). For the introduction of WSP into Korea, 150 hazards were identified all steps in drinking water supply from catchment to consumer and risk assessment tool based on frequency and consequence of hazards were developed. Then, developed risk assessment tool by this research was implemented at a water treatment plant(Q=25,000 m3/d) to verify its applicability, and several amendments were recommended; classification of water source should be changed from groundwater to stream to strengthen water quality monitoring contaminants and frequencies; installation of aquarium to monitor intrusion of toxic substances into raw water; relocation or new installation on-line water quality analyzers for efficient water quality monitoring; change of chlorination chemical from solid phase(Ca(OCl)2) to liquid phase(NaOCl) to improve soundness of chlorination. It was also meaningful to propose hazards and risk assessment tool appropriate for Korea drinking water supply systems through this research which has been inconsistent among water treatment authorities. Key words: Hazard, Reliability, Risk management, Water safety plan, Tap water

물거미는 한국에서 유일하게 연천군 은대리의 좁은 습지에서만 제한적으로 분포하고 있다. 이 연구에서는 물거미 개체군에 영향을 주는 서식 환경요인을 규명하기 위하여 습지내 물거미의 개체수와 수생태계의 다양한 물리화학 및 생물학적 환경요인과의 관계를 조사하였다. 그 결과 물거미의 개체수는 서식지의 물리화학적 환경요인 중에서 습지의 면적이 좁고 암모니아태질소와 전기전도도가 높을수록 증가하였다. 물거미는 포식자나 먹이인 피식자와는 관련성이 낮고 왕우렁이의 개체수가 많을수록 감소하였다. 또한 정수식물의 피도와는 관련성이 없었으나 부엽식물의 피도가 높을수록 물거미수는 감소하였고, 그 반대로 침수 식물의 피도가 높을수록 이에 비례하여 물거미 수는 증가 하였다. 이러한 결과는 물거미의 서식환경에서 수생식물이 중요하게 관련됨을 의미하고, 현재 이 서식지에서 외래종인 왕우렁이는 수생식물의 최대 섭식자로 작용하고 있으므로 이에 대한 제어대책이 시급히 필요하다.

To understand the effect of high pressure on nitrogen oxides (NOx) formation in water added methane flames, opposed nonpremixed Water-methane/air (H2O-CH4/air) flames are numerically studied with high initial pressure. With GRI 3.0 detailed kinetic mechanism, NOx emissions are predicted for various strain rates. Due to high pressure, the chemical species are distributed in a narrow region, which means the thickness of the flame is thin. This can be clearly seen with high strain rate. Elevated pressure increases maximum temperature of flames which results in increased NOx emission. Even with elevated initial pressure, NOx emissions for H2O added methane flames are significantly decreased compare to pure methane flame. In addition, increased strain rate is also significant factor for decreasing NOx emission. With detailed rate of production analysis, in case of high pressure, it is confirmed that NO2 pathway is the most dominant reaction pathway than any other pathways.

본 실험은 물냉이 수경재배 시 양액 내 발생 시킨 마이크로버블이 물냉이의 생육과 glucosinolate 축적에 미치는 영향을 알아보기 위해 수행되었다. 본엽 4매의 물냉이 유묘(파종 2주 후)를 마이크로 버블과 비-마이크로버블을 발생시킨 오오츠카 배양액을 이용하여 환경조절룸에서 3주간 재배하였다. 물냉이 초장은 대조구처리가 마이크로버 블처리보다 41% 증가하였으며, 유의적으로 높게 나타났다. 그러나, 지상부 생체중과 건물중, 근장, 엽장, 엽폭, SPAD, 량자수율값은 두처리간 유의적 차이는 나타나지 않았다. Glucosinolate 함량을 분석 결과 4-methoxygluco-brassicin을 제외한 glucoiberin, glucobrassicin, gluconapin, gluconasturtiin의 경우 마이크로버블 처리구가 대조구보다 유의적으로 높게 나타났으며, 물냉이 한주 당 총 glucosinolate 함량은 마이크로버블 처리구가 대조구 보다 85%(μmol/g DW)와 65%(μmol/plant) 더 높게 나타났다. 본 연구 결과는 담액재배시 양액 내 마이크로버블 이 물냉이의 glucosinolate 함량을 증가시킬 수 있을 것으로 나타났다.

본 연구에서는 분류학적 실체에 대해 많은 논쟁이 있어왔던 황철나무와 물황철나무의 분류학적 재검토를 통해 두 분류군의 유연관계를 밝히기 위하여 엽형질과 미세형질들을 분석하였다. 엽의 크기를 암·수 구분 없이 전체 평균 너비, 길이, 면적으로 비교한 결과 종간 및 종내 모두 1%에서 고도의 유의차가 검증되었고, 황철나무는 55.56 mm, 73.5 mm, 28.72 mm2, 물황철나무는 76.80 mm, 117.82 mm, 68.61 mm2로 측정되어 황철나무의 엽 생장은 물황철나무에 비해 작은 것으로 나타났다. 황철나무의 엽병과 엽맥에는 털이 발견되지 않았지만 물황철나무의 엽병과 엽맥에는 양면 모두 털이 밀생하였다. 성숙한 황철나무의 삭과는 3개로 갈라지며 동일한 시기에 물황철나무는 4개로 갈라지는 것으로 확인되었다. 조사된 형질을 종합한 결과, 황철나무와 물황철나무의 종간 분류에 중요한 정보를 주는 요인으로는 잎의 크기와 삭과가 터지는 유형, 엽병 털의 유무 등이 있었다.