• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.430-430
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• 2012

Modulated pulsed power (MPP) 스퍼터링은 펄스 전압 shape, amplitude, duration의 modulation을 통해 증착율 손실을 극복하는 고출력 펄스 마그네트론 스퍼터링의 한 종류이다. Micro second 범위에서 on/off 시간을 다중 세트 형태로 자유롭게 프로그램 할 수 있어서 아킹 없이 고전류 영역의 마그네트론 동작을 할 수 있으므로, 고주파 유도 결합 플라즈마원이나 마이크로웨이브 투입 등의 부가적인 플라즈마 없이도 스퍼터링 재료의 이온화 정도를 획기적으로 높일 수 있는 장점을 가지고 있다. 본 연구에서는 $2{\times}1{\times}0.2$의 sputtering system에서 기판 캐리어를 이용해서 $400{\times}400mm$ 기판을 $272{\times}500mm$ 크기의 AZO target (Al 2 wt%)이 설치되어 있는 moving magnet cathode (MMC)을 이용하여 MPP로 증착했다. 두 종류의 micro pulse set을 하나의 macro pulse에 사용함으로서 weakly ionized plasma와 strongly ionized plasma를 만들 수 있다. 다양한 micro pulse set을 이용하여 평균 전력 2 kW에서 peak 전력을 4 kW에서 45 kW까지 상승 시킬 수 있으며, 이 때 타겟-기판 거리 80 mm에서 이온전류밀도는 $5mA/cm^2$에서 $20mA/cm^2$까지 상승했다. MPP는 같은 평균 전력에서 repetition frequency가 증가할 때, 증착 속도가 증가했으며, 같은 repetition frequency에서 macro pulse length가 증가할 때도, 증착 속도가 증가했다. 최적화된 marco, micro pulse set에서 증착 속도는 평균 전력 2 kW에서 110 nm/min이었고, 700 nm의 박막에서 비저항은 $1-2{\times}10^{-3}ohm{\cdot}cm$였다. 표면거칠기 Rrms는 약 3 nm였고, 400-700 nm 영역의 평균 투과도는 72-76%였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.287-287
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• 2008

HTS-케이블은 구리도체 대신 고온초전도도체를 사용하여 저항이 0이 되는 초전도현상을 이용하여 대용량 전력수송이 가능한 전력케이블로서 대도시의 전력부하 집중문제를 해결할 수 있는 환경 친화적 전력케이블이다. 최근 고온초전도선재의 고임계전류밀도화 및 장척화에 힘입어 HTS-케이블의 실용화를 목표로 경제성이 있는 전력케이블을 개발하려는 움직임뿐만 아니라 실증시험 등 활발한 연구가 진행 중이다. 그러나 초전도전력케이블에서 발생되는 교류손실은 케이블의 효율을 저하시킬 뿐만 아니라 냉동기비용 증가로 인한 기존 케이블과의 가격경쟁에서 경제성을 저하시키는 주된 요인으로 작용하기 때문에 이의 상용화에 앞서 교류손실에 대한 정확한 규명이 되어야 하며 또한 실계통 투입 시 중요한 선로임피던스에 대한 정확한 규명도 필요하다. 본 논문에서는 실제 한전 주관으로 고창시험장에 설치된 배전급 22.9 kV, 100 m, 50 MVA급 3 상 HTS-케이블에 대한 통전특성을 규명하기 위하여 먼저 HTS-케이블의 DC 통전특성을 조사하였다. 또한 3상평형운전상태에서 AC 통전특성(인덕턴스 및 교류손실)을 실험적으로 조사하였으며 5m-케이블에서 측정된 결과와 비교 검토하였다.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.325-326
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• 2017

태양광 발전의 DC 전압 출력 및 케이블을 이용한 해상풍력 발전과 같은 신재생 에너지 이용이 증대되고 있다. 또한, 에너지의 전력전송 대용량화에 따른 기존의 AC 전력전송 방식을 개선한 DC 전력전송에 대한 연구가 활발히 연구되고 있다. DC 전력전송은 송전선로의 원거리화 및 절연내력의 저감과 같은 장점이 있으나, 전류 차단 시 큰 아크로 인하여 고속차단기 구성이 매우 어렵다는 단점이 있다. 최근에는 DC 전력전송에 있어서 큰 과제인 고속차단을 위해 전자식 차단기에 대한 연구가 이루어지고 있다. 이러한 전자식 차단기를 구성할 경우 차단기 투입 시 큰 돌입전류와 입출력 절연저항이 기존 차단기보다 낮아지는 단점으로 인해 매우 큰 아크가 발생한다. 본 논문에서는 고 전압 대 전류에 적합하고 피크성 전압/전류에 강인한 소자인 SCR을 이용한 전자식 DC 차단기 연구를 진행하였다.

• Korean Journal of Organic Agriculture
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• v.26 no.2
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• pp.297-316
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• 2018

The golden apple snail (GAS, Pomacea canaliculata) is an invasive freshwater snail. The GAS was introduced in Korea without prior studies on the possibility of crop damage or its impact on the natural ecosystem. The freshwater apple snails can be found typically in ponds, rice paddies, irrigation canals, roadside ditches or slower portions of streams. In this study, we were carried out to investigate the assessment of physiological and ecological characteristics, environmental characteristics inhabited area in winter season and cause of massive death at one time of golden apple snails used for weed control in wet rice paddies. The GAS was introduced from Japan to Korea for commercial production as a dietary protein supplement. The golden apple snail was also used a recently for weed control in wet rice cultivation. The species of freshwater Pomacea snails is belonging to the genus Pomacea, family ampulariidae, order mesogastropoda, subclass pulmonata, class gastropoda, phylum mollusca. The GAS spread into irrigation ditches and natural waterways. It is now distributed in ponds and canals near rice fields of southern parts of the country and has overwintered. It increases its cold hardiness before winter. However, the physiological mechanism of cold hardiness in molluscs is poorly understood, especially in freshwater molluscs. Our results on physio-ecological characteristics of the Pomacea apple snail showed that the ratio of males to females was 1: 1.99~2.33. The daily growth was 87.7 mg in weight, 0.31 mm in height and 0.33 mm in width of the their shell. On the other hand, the golden apple snails were very high to resistance on drying condition and survived rate about 80% up to 3 months. The inhabitation of GAS was no statistical significant impacts on the water quality. An important property of aqueous solutions is agricultural water quality because it affects chemical and biochemical properties such as chemical reactions, equilibrium conditions, and biological toxicity. The death rate of weed control apple snails by Ostracoda (Stenocypris hislopi) was only 2.86% and 5.71% depending on the density. Therefore, GAS was not a direct death caused by Ostracoda (Stenocypris hislopi).

• Journal of agriculture & life science
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• v.53 no.5
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• pp.137-143
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• 2019

To manufacturing of solid fuel by reuse of the wastes, the drying unit which have 500 kg/hr of drying capacity was developed and experimentally evaluate the performance. The spinach grown in Nam-hae island were used for the experiments and investigated of the heated-air drying characteristics as the inlet amount of raw materials, raw material stirring status, conveying type and drying time. The drying air heated by the energy derived from the steam which is supplied from the incineration plant. The moisture contents of raw materials were measured 85.65%. The inlet flow rate of drying air made a difference as the depth of the raw materials loaded on the drying unit and temperature has showed 108~144℃. The drying speed of the mixed drying more than doubled as that of non mixed drying under the same drying type, inlet amount, drying time and drying air temperature. In each experiment, the drying capacity have showed over 500 kg/hr. A drying efficiency of the ratio of drying consumption energy to input energy was 33.46%, lower than the average of 57.76% for the 157 conventional dryers. Because developed dryer must have a drying time of less than one hour, it is considered that the dry efficiency has been reduced due to the loss of wind volume during drying. If waste heat from incineration plant is used as a direct heat source, the dry air temperature is expected to be at least 160℃, greatly improving the drying capacity.

• Horticultural Science & Technology
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• v.30 no.2
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• pp.192-200
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• 2012

For the development of genetically modified plants, it is important to verify various factors which potentially affect the risk assessment as well as to establish an experimental program to produce scientific and reliable data. However, it is a time and cost consuming process to develop GM plants as well as to prepare scientific and convincible data for government's approval. Therefore, using the transgenic hot pepper tolerant to a new CMV pathotype, we attempted to suggest few methodological procedures, such as probe saturation for southern blot analysis and RT-PCR and ELISA for expression analysis, for identification and stability evaluation of inserted gene in genetically modified plant which are required for submission for approval. Ten partially overlapped probes covering full length of inserted gene were produced. We could identify that the inserted gene was stacked as a single copy as well as no partial element existed. Also, we could identify the stability of the inserted gene stacked in hot pepper using probe saturation. In the expression analysis with RT-PCR and ELISA, we also could provide the stable expression of transcript and proteins in leaves and placenta and pericarp of fruits of the CMV-resistant hot pepper.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.135-142
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• 2021

In this work, multi-turn wings and guide plates are installed on recycled aggregate crushing devices to improve existing low recycled aggregate quality. Simulation analysis to evaluate the crushing efficiency of the new device shows enhanced crushing efficiency since the installation of guide plates shreds most of the inputs inside the crushing drum, and the multi-turn wings and guide plates induce rebound and circulation of the aggregate. Through this, the new device was found to be more economical and efficient than the existing recycled aggregate crushing device. Also, the amount of cement paste and mortar attached to the surface of the aggregate was smaller than that of the existing recycled aggregate, and it was found that the mechanical properties and elastic modulus deterioration were reduced. However, the carbonation resistance of concrete was not improved to the level of natural aggregates due to the remaining tiny cement paste and mortar on the surface of the new recycled aggregate. Therefore, it is deemed necessary to further research and experiment such as device improvement or binder development to reduce durability degradation of concrete mixed with new recycled aggregate.

• Korean journal of applied entomology
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• v.52 no.4
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• pp.437-448
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• 2013

Hemipteran bugs, which were previously considered as secondary pests, have currently become important pests of numerous crops. Among them, Riptortus pedestris (Fabricius) is a major species that occurs in Korea, Japan, China, and South Asian countries. Riptortus pedestris infests leguminous crops like soybean, vetches, and red clover; fruit trees like persimmon and yuju; and grains like barley, foxtail millet, broomcorn, and sorghum. Riptortus pedestris causes the greatest damage to soybean, as it is the most suitable host for the bug. Feeding damage during pod formation significantly reduces the yield of soybean. Currently, 17 insecticides, including diazinon and etofenprox, are registered for the control of hemipteran bugs in Korea, and growers apply insecticides two to three times on a regular basis. Aggregation pheromone traps are widely used as a monitoring tool and partial control measure. The aggregation pheromone of R. pedestris attracts conspecific adults and nymphs and is used for food exploitation rather than sexual attraction. In addition, the pheromone serves as a kairomone for egg parasitoids such as Gryon japonicum (Ashmead) and Ooencyrtus nezarae Ishii. As a new method of pest management, nonviable host eggs were included in the pheromone trap to catch R. pedestris and propagate parasitoids. As a part of cultural practices, resistant soybean varieties with specific color and size of pod and control of flowering time through the alteration of planting date can be used. For the effective management of R. pedestris in the near future, development of cultural practices that can support natural control factors and the use of multiple control tactics are needed.

• Journal of Energy Engineering
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• v.19 no.2
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• pp.116-120
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• 2010

Overall total length of hydraulic pipe to transport the hot water in the domestic district heating network is above 3,000 Km approximately. This long pipe network requires a lots of the transport pumping power by surface friction of fluid. In this study, the drag reduction(DR) of Amin Oxide $C_{18}$ as non-ionic surfactant according to the fluid velocity, temperature and surfactant concentration under the condition of above $80^{\circ}C$ fluid temperature were investigated experimentally. Results showed that new amin oxide $C_{18}$ surfactant had DR of maximum 30% in fluid temperature of $80^{\circ}C$ and had 15% DR in fluid temperature over $100^{\circ}$ under short time test condition. And amine oxide had 155 hours duration time to keep the DR characteristic in the fluid temperature of $80^{\circ}$ and 1000 ppm concentration. But duration time of DR was decreased when fluid temperature increased.

• Journal of the Korean Wood Science and Technology
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• v.41 no.3
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• pp.234-246
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• 2013

It was found that test piece heated rapidly by 3 kW microwave for 5 minutes satisfies the targeted temperature and the percentage of moisture content, and the highest rate of weight increase is obtained in case of 120 minute immersion in the mixture of phosphates and heterocyclic compounds, from the result of such analysis as: kiln drying schedule, flame retardent by flammability test, insect resistance by termites, and permeability of combined penetrant for the wood after assigning multifunctional finish by immersing conifer structural frame, which is used for the frame work of wooden house and indoor/outdoor finishing in flame retardant and insect repellent materials mixture with the remaining heat of microwave. In addition, after a test of flame retardent treated item, it was identified that every mixture of phosphates corresponds with the standards of flame retardent, and upon investigation of moritality of 7 days after putting termites, it was showed that test piece immersed in the mixture of phosphates and heterocyclic compounds has the best characteristics, showing over 96% of high moritality. From the analysis of inward permeability of combined penetrant for the wood, it was decided that excellent performance in the flame retardent and insect resistance of the wood revealed due to full penetration of combined penetrant as it was found that combined penetrant penetrated through the whole inner cells of the wood.