• Corrosion Science and Technology
• /
• 제12권3호
• /
• pp.125-131
• /
• 2013

The most common pipe wall thinning degradation mechanisms that can occur in the steam and feedwater systems are FAC (Flow Acceleration Corrosion), cavitation, flashing, and LDIE (Liquid Droplet Impingement Erosion). Among those degradation mechanisms, FAC has been investigated by many laboratories and industries. Cavitation and flashing are also protected on the piping design phase. LDIE has mainly investigated in aviation industry and turbine blade manufactures. On the other hand, LDIE has been little studied in NPP (Nuclear Power Plant) industry. This paper presents the development of prediction system for pipe wall thinning caused by LDIE in terms of erosion rate based on air-water ratio and material. Experiment is conducted in 3 cases of air-water ratio 0.79, 1.00, and 1.72 using the three types of the materials of A106B, SS400, and A6061. The main control parameter is the air-water ratio which is defined as the volumetric ratio of water to air (0.79, 1.00, 1.72). The experiments were performed for 15 days, and the surface morphology and hardness of the materials were examined for every 5 days. Since the spraying velocity (v) of liquid droplets and their contact area ($A_c$) on specimens are changed according to the air-water ratio, we analyzed the behavior of LDIE for the materials. Finally, the prediction equations(i.e. erosion rate) for LDIE of the materials were determined in the range of the air-water ratio from 0 to 2%.

• 한국산림과학회지
• /
• 제98권5호
• /
• pp.539-547
• /
• 2009

This study was conducted to investigate the arbuscular mycorrhizal fungal biodiversity, spore density and root colonization in relation to site ages at expressway cut-slopes in Korea. Stabilization of exposed surface involved soil amendments and spraying seed mixture of turf grasses and/or nitrogen-fixing shrub species. Eighteen sites were selected with varying ages (2 to 16 years). Soil samples collected in October from each site were analyzed for fungal diversity and spore counts. Fine root samples from the plants were assayed for fungal colonization. Of the total 37 plants inspected in the sites, 26 species had endomycorrhizal colonization with an average root colonization rate of 18%, and with a range from 1 to 67%. The average endomycorrhizal colonization rate of initially introduced Festuca arundinacea which became the most dominant grass in later stage showed 22.8%, while that of Lespedeza bicolor which became the most dominant woody species were 21.6%. Naturally-invading Robinia pseudoacacia showed higher colonization rate in the old sites. Although site age did not show significant effects on fungal diversity, the root colonization rates of initially introduced plants decreased with the site aging, while those of invading plants increased with aging of the sites. The soil chemical properties, pH, N, and P contents, were negatively correlated with spore density, root colonization and endomycorrhizal species diversity. A total of forty arbuscular mycorrhizal fungal species in seven genera were identified. Of the 40 species, Acaulospora lacunosa, Glomus aggregatum, Glomus constrictum, Scutellospora erythropa, and Acaulospora spinosa were the five most dominant species in the decreasing order.

• 한국전기전자재료학회논문지
• /
• 제37권1호
• /
• pp.79-87
• /
• 2024

This paper is a study on the optimal microdroplet generation conditions in indirect charging electrostatic spraying. Unlike the direct charging method, which applies power to the nozzle, the indirect charging method applies power to the discharge electrode between the nozzle and the collection electrode. Therefore, an electrically simplified system can be obtained by minimizing the insulation part a stable spray pattern can be obtained with a wide spray angle, and a stable spray pattern can be obtained with a wide spray angle. To conduct the study, an indirect charging type electrostatic spray visualization system was constructed and the static characteristics of the microdroplets were analyzed through image processing of the spray shape of the microdroplets. The total number of microdroplets and the number of microdroplets per power consumption are confirmed according to the changes in the distance between the discharge electrode and the collection electrode, the flow rate, and the applied voltage, which affect the generation of microdroplets, and using this, the optimal generation conditions are derived and the corresponding microdroplet size distribution was analyzed. As a result of the experiment, it was confirmed that the optimal generation condition was at a flow rate of 15 to 20 mL/min and a voltage of -22.5 to -25 kV in terms of the number of microdroplets, and at a flow rate of 15 to 20 mL/min and a voltage of -20 kV in terms of energy consumption efficiency.

• Current Research on Agriculture and Life Sciences
• /
• 제2권
• /
• pp.23-28
• /
• 1984

보리 및 맥주맥의 발아율(發芽率), 초장(草長) 및 생장율(生長率)에 미치는 전처리(前處理)의 효과(效果)를 조사(調査)하기 위하여 1984년(年) 11월(月) 5일(日)부터 12월(月) 5일(日)까지 실시(實施)한 본(本) 실험(實驗)의 결과(結果)는 다음과 같다. 공시(供試)한 각(各) 보리 품종(品種)들의 prechilling 처리(處理)에 대한 효과(效果)는 5~8일간(日間)의 처리(處理)에서 발아율(發芽率)이 가장 높았고, 맥주맥은 8일간(日間)의 처리(處理)에서 가장 높았다. predrying에서는 사천 6호(號)만 5일간(日間)의 처리(處理)에서 발아율(發芽率)이 가장 높았고, 그 외의 품종(品種)들은 공(供)히 7일간(日間)의 처리(處理)에서 가장 높은 발아율(發芽率)을 보였다. 생장율(生長率)은 모든 품종(品種) 공(供)히 5~8일간(日間)의 Prechilling 처리(處理)에서 가장 높았으며, Predrying은 오월보리와 향맥이 3일(日), 사천 6호(號) 5일(日) 및 알보리 7일간(日間)의 처리(處理)에서 각각(各各) 높은 생장율(生長率)을 보였다. 초장(草長)은 모든 보리 품종(品種) 공(供)히 5일간(日間)의 Prechilling 처리(處理)에서 가장 길었으며, 맥주맥 품종(品種)들은 8일간(日間)의 처리(處理)에서 가장 길었다.

• Bulletin of the Korean Chemical Society
• /
• 제33권8호
• /
• pp.2539-2545
• /
• 2012

In the present study, we suggest a new way to reactivate performance of direct formic acid fuel cell (DFAFC) and explain its mechanism by employing electrochemical analyses like chronoamperometry (CA) and cyclic voltammogram (CV). For the evaluation of DFAFC performance, palladium (Pd) and platinum (Pt) are used as anode and cathode catalysts, respectively, and are applied to a Nafion membrane by catalyst-coated membrane spraying. After long DFAFC operation performed at 0.2 and 0.4 V and then CV test, DFAFC performance is better than its initial performance. It is attributed to dissolution of anode Pd into $Pd^{2+}$. By characterizations like TEM, Z-potential, CV and electrochemical impedance spectroscopy, it is evaluated that such dissolved $Pd^{2+}$ ions lead to (1) increase in the electrochemically active surface by reduction in Pd particle size and its improved redistribution and (2) increment in the total oxidation charge by fast reaction rate of the Pd dissolution reaction.

• 대한기계학회논문집B
• /
• 제27권1호
• /
• pp.125-134
• /
• 2003

The present paper is concerned to the thermal analysis during the cool-down period of 138,000 m$^3$class GTT MARK-III membrane type LNG carrier servicing with LNG from the Middle East to Korea. It is the cool-down period that cools the insulation wall and the gas in LNG tank to avoid the thermal shock as the start of loading of -162$^{\circ}C$ LNG. For six hours of the standard cool-down period, the temperature of NG falls down from -4$0^{\circ}C$ to -13$0^{\circ}C$ and especially the mean temperature of the 1st barrier in the top side insulation wall falls down from -38.38$^{\circ}C$ to -122.42$^{\circ}C$ in case of IMO design condition. By the 3-D numerical calculation about the cargo tank and the cofferdam, the temperature variation in hulls and insulations is precisely predicted in this paper. And the mean temperature variation of gas is calculated as the function of the spraying rate by the heat balance model during the cool-down period.

• 한국잠사곤충학회지
• /
• 제33권1호
• /
• pp.6-8
• /
• 1991

낙엽전 상묘의 조기 굴취에 따라 예상되는 묘질의 악화를 예방하고 굴취작업 불편 등을 해소하기 위해서 수원 2개 장소, 공주, 청주, 장성 등 6개 지역에서 탈엽제인 에스렐 (2-chloroethylphosophonic acid, 39%) 400배액(약 1,000ppm)을 10월 10일부터 5일 간격으로 10월 30일까지 처리마다 한번씩 뽕잎에 살포하고 활착율과 묘질을 조사하였다. 1. 10a당 살포 소요 시간은 3.3시간, 엽량은 500$m\ell$ 소요되었다. 2. 10월 20일 이전 살포는 지역에 따라 활착율을 5-8% 감소시켰다. 3. 식재후 신초의 길이와 개수는 처리간에 차를 인정할 수 없었다. 따라서 지역에 관계없이 10월 20일 이후 살포할 경우 활착율과 식재후의 생육이 자연 낙엽한 묘목과 차가 없을 것으로 판단되었다.

• 한국가금학회지
• /
• 제19권1호
• /
• pp.17-25
• /
• 1992

The efficacy of B$_1$l live vaccine which is used successfully in chicken was examined against Newcastle disease in quails. A total of 480 male quails were divided into 4 groups, of which 3 groups were vaccinated via drinking water, eye instillation and spraying method and the remaining was employed as a nonvaccinated control group. At 3 weeks after the first vaccination a part of quails in each group was revaccinated. Efficacy of the vaccine was evaluated by the antibody responses and the protection rates after challenge with a virulent NDV. Vaccination of quails with $B_1$ NDV at 10 days of age resulted in beneficial effect compared to nonvaccinated group regardness of vaccination methods adopted although general protection rates were considerably low. Twice vaccination gave higher protection than once vaccination. Hemagglutination inhibition antibody responeses were significantly higher in groups of quails vaccinated by spray and eye instillation method than by drinking water administration. Antibody responses were marked at 2 weeks onward and until 5 to 7 weeks after vaccination. Antibody responses were rapid and marked after second vaccination. However, antibody level did not last longer than 5 to 7 weeks postvaccination. Vaccine caused no adverse effect on quails in terms of growth'rate, body temperature or clinical signs.

• 한국응용과학기술학회지
• /
• 제35권1호
• /
• pp.284-291
• /
• 2018

본 연구에서는 식품 및 화장품 원료로 널리 사용되는 천연 다당류의 분자 구조, 분자량, 점도, 친수성, 팽창, 습윤 및 보습 특성을 이용하여 도로 분진 방지제를 제조하였다. 다양한 분진 제어 효과가 확인되었으며 단순한 물 분사 및 시험 대조군인 합성PVA보다 우수한 결과를 얻었다. 또한 수분증발 비교, 비산 저감율, 공사현장 테스트 및 물벼룩 급성 독성 시험 등의 영향을 연구하고 토양 및 수질의 안전성을 연구하여 도로 분진 방지제의 유용성을 확인하였다.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.217-217
• /
• 2006

The surface energy control capability of electrohydrodynamic force provides electrospraying with various potential advantages such as simple particle size control, mono-dispersity, high recovery, and mild processing conditions. Herein, the one step nano-encapsulation of protein drugs using electrospraying was developed. The major processing parameters such as the conductivity of spraying liquids, flow rate, the distance between electric potentials, etc were examined to obtain the maximum efficiency. The recovery of particles was found relatively high as could be conjectured based on the principle of electrospraying. When organic solvents were employed, the processing windows of electrospraying were relatively narrow than water systems. Efficient nano-encapsulation of BSA with polymers was conveniently achieved using electrospraying at above 12 kV.