• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.5
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• pp.727-733
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• 1995

This stduy was attempted to establish the basic data for evaluating chemical components in the sap from birches(Betula platyphylla Sukatschev, Betula costata Trautv, Betula davurica Pallas), bamboos(Phyllostachys pubescens, Phyllostachys bambusoides, Phyllostachys nigra), Darae(Actinidia arguta). Calcium and potassium in five kinds of mineral detected in the sap were dominant mineral, magnesium, sodium and iron in order and calcium, potassium and magnesium are abundant in the sap from bamboo more than the other sample and the contents were 242.0~422.1mg/L, 793.8~ 2504.1mg/L and 72.6~165.9mg/L, respectively. Free sugars of the sap determined were glucose, fructose and sucrose, but maltose was not detected. The contents of glucose and fructose of the sap from Betula platyphylla Sukatschev(#2) were the highest and 42.1g/L and 36.9g/L, respectively. The detectabel nucleotides and their related compounds were CMP, UMP, GMP, IMP, AMP and hypoxanthine. The total contents of composition amino acids detected from eighteen kinds of the sap were in the range of 2.4~30.4mg%. The major amino acids were taurine, glycine, lysine, alanine and threonine in the sap from birch(#1, #2), glutamic acid and lysine in the sap from Betula costata Trauty(#3) and Betula davurica Pallas(#4), lysine, valine, alanine, serine, tyrosine and glutamic acid in the sap from bamboos, and glutamic acid, leucine, alanine in the sap from Darae.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.209-215
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• 2015

Miraculous victory of Myeongnyang sea battle turned the tide of the Joseon's entire war against Japan and it is regarded as one of the most remarkable sea victories in the world history. In the sea battle of Myeongnyang, on September 16, 1597(lunar calender), the Joseon navy with 13 battle ships, led by Admiral Yi Sun-sin, won the Japanese navy with their fleet of 133 warships. There were several reasons why Admiral Yi decided on this location for battle. Myeongnyang strait is so narrow and had currents so powerful that many ships could not pass strait simultaneously. Therefore, despite being vastly outnumbered, Admiral Yi used terrain and tidal current advantage to defeat Japanese navy's numerical advantage. In order to find out the tidal state of Myeongnyang strait on September 16, 1597, topological phase of sun and moon was studied by orbital period of earth and moon. The tidal state of Myeongnyang strait on September 16, 1597 is estimated based on the theories of tide and tide tables. As a result of this study, time of slack water were found to be 0636, 1248, 1906 and time/speed of maximum tidal current were found to be 0930/8.3kts(NW), 1612/9.9kts(SE).

• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.59-66
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• 2018

Using hydrogen fuel is expected to be suitable as a reciprocating internal combustion engine with heightened interest in HALE(High Altitude Long Endurance) UAV(Unmanned Aerial Vehicle). Hydrogen is hightest energy density per mass so it can continue to charge for long periods of time and have positive part of the environmental effects. However, it is estimated that there is less research on hydrogen fuel engine currently applied, and many studies need to be done. Depending on the operation, there are factors that result in supercooling due to reduced radiation or reduce cooling performance due to low air density. Therefore, the experiment was to change the temperature of the cooling water and investigate the effect on engine combustions. The limitation of the stable operation range due to backfire is dominated by the excess air ratio rather than the effect of the cooling water temperature change. When the cooling water temperature increases, the volumetric efficiency decreases and the torque decreases. As the cooling water temperature decreases, the heat loss was increased and consequently the thermal efficiency was decreased.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.211-218
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• 2012

Fossil fuel is used all over the world and it produces greenhouse gases due to fossil fuel use. Therefore, it cause global warming and is serious environmental pollution. In order to decrease the environmental pollution, we should use renewable energy which is clean energy. Among several renewable energy, wind energy is the most promising one. Wind power generation is does not produce environmental pollution and could not be exhausted. However, due to wind power generation has irregular power output, it is important to predict generated electrical energy accurately for smoothing wind energy supply. There, we consider use ramp characteristic to forecast accurate wind power output. The ramp increase and decrease rapidly wind power generation during in a short time. Therefore, it can cause problem of unbalanced power supply and demand and get damaged wind turbine. In this paper, we make prediction models using power ramp rate as well as wind speed and wind direction to increase prediction accuracy. Prediction model construction algorithm used multilayer neural network. We built four prediction models with PRR, wind speed, and wind direction and then evaluated performance of prediction models. The predicted values, which is prediction model with all of attribute, is nearly to the observed values. Therefore, if we use PRR attribute, we can increase prediction accuracy of wind power generation.

• Journal of Korean Society of Forest Science
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• v.61 no.1
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• pp.27-36
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• 1983

This study was performed to get the basic information on nitric acid pulping of beech wood. In order to reduce the consumption of nitric acid, alkali pretreated woods were applied to a nitric acid pulping process. It consisted of nitric acid treatment to a high residual lignin content and the subsequent delignification with alkali, required far less chemical than the single stage method. At the first stage of nitric pulping, pulp yield descreased with increasing cooking time and 3 percent of nitric acid was more effective on the delignification of wood than 1 or 2 percent. Alkali pretreatment of wood improved significantly the rate of delignification, and 79 percent of the pretreated yield was good enough for excellent delignification. The dissolution of carbohydrate (mainly xylose) was increased with increasing cooking time, especially at the second stage. It would be considered that carbonyl groups introduced to polysaccharides in wood by nitric acid oxidation caused the degradation of carbohydrates.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1993.05a
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• pp.90-95
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• 1993

수력, 화력, 원자력 다음으로 제 4의 전원으로서 관심의 대상이 되고 있는 연료전지는 연료가 가지고있는 화학에너지를 직접에너지로 변환시키는 점에서 종래의 발전 기술과는 원리적으로 다르며, 카르노(Carnot)사이클에 의한 에너지 변환 효율의 제한을 받지 않기 때문에 효율이 높으며 공해가 없는 특징을 가지고 있다. 연료전지의 발전 방식은 작동 온도, 전해질 등에 의해서 분류되나 현재 실용화단계의 기술은 인산형연료전지 발전이다. 인산형 연료전지의 발전용 연료는 천연가스, 메탄올, 납사 등과 같은 탄화수소 계열의 다양한 연료를 사용할 수 있으며, 이들 연료들을 수소가 많이 함유된 가스로 변환시켜 연료전지에 공급하여야 한다. 연료전지발전시스템 개발은 주로 전력이용 측면에서 천연가스를 개질연료로 사용하는 연구가 주류를 이루었으나, 최근에는 전 세계적으로 대기 공해에 시달리고 있는 도시의 환경개선을 위하여 도심용 버스 및 대형 트럭 등에 응용하기 위한 무공해 수송용 자동차엔진의 개발, 국방용 이동전원 개발 및 100㎾ 미만의 현지설치용 및 낙도용 전원으로서 메탄올을 연료로 한 연료전지의 개발이 활발히 진행되고 있다. 한국에너지기술연구소는 한국전력 기술연구원과 공동으로 1989년부터 1992년까지 본체를 제외한 5.9㎾급 인산형 연료전지 발전시스템 즉, 메탄올 연료 개질장치, 운전자동화 시스템, 배열이용 시스템, 종합 배관 등을 설계 구성하여 발전 플랜트의 운전 특성 연구를 수행하였으며, 본 고에서는 이들 설비들의 운전 특성과 발전 플랜트로서의 효율 특성에 대한 고찰을 수행하였다. 본 시스템은 연료개질기가 연결되고 배열을 이용하는 국내최초의 종합적인 연료전지 발전 시스템으로서 개질된 연료로 운전하였을 경우 본체의 효율은 31.9%, 배열을 회수한 종합발전 플랜트의 효율은 45.2%였다.로서, 흰쥐 유선이 LH의 생성처이면서 동시에 작용처이며 유선에서 합성된 GnRH의 조절하에 국부적인 인자로 작용할 가능성을 시사한다.f variation)가 10% 내외로 만족할 만한 범위에 들었다. 본 실험 방법을 타액과 혈청내 testosterone 농도 측정에 응용하여 RIA의 결과와 비교하여 본 바 상관관계가 타액에서 r=0.969, 혈청에서 r=0.990으로 두 결과가 잘 일치하였다. 본 실험에서 측정된 한국인 여성의 타액내 testosterone농도는 107.7$\pm$12.0 pmol／l이었고, 남성의 타액내 농도는 274.2$\pm$22.1 pmol／l이었다. 이상의 결과로 보아 본 연구에서 정립된 EIA 방법은 RIA를 대신하여 소규모의 실험실에서도 활용할 수 있을 것으로 사려된다.또한 상실기 이후 배아에서 합성되며, 발생시기에 따라 그 영향이 다르고 팽창과 부화에 관여하는 것으로 사료된다. 더욱이, 조선의 ${\ulcorner}$구성교육${\lrcorner}$이 조선총독부의 관리하에서 실행되었다는 것을, 당시의 사범학교를 중심으로 한 교육조직을 기술한 문헌에 의해 규명시켰다.nd of letter design which represents -natural objects and was popular at the time of Yukjo Dynasty, and there are some documents of that period left both in Japan and Korea. "Hyojedo" in Korea is supposed to have been influenced by the letter design. Asite- is also considered to have been "Jap

• KSBB Journal
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• v.14 no.3
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• pp.303-308
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• 1999

An in vitro culture method for entomopathogenic nematode Steinernema glaseri was developed. A symbiotic bacterium was isolated from Steinernema glaseri and identified as Xenorhabdus nematophilus. Phase variation that differed in some biochemical characteristics of symbiotic bacterium was observed. Entomopathogenic nematodes carried only phase I bacterium in their guts. Phase I bacterium could be converted into phase II form in in vitro culture medium consisting of 5% yeast extract, 0.5% NaCl, 0.05% $K_2HPO_4$, $0.02% MgSO_4$.$7H_2O$. The optimum temperature for bacterial growth was $28^{\circ}C$. The pH of the culture medium increased up to 9.0-9.5 during the exponential growth period of the culture, regardless of initial pH 6-7. Various culture media such as chicken offal, dog food, bovine liver, peanut, and so on were tested for in vitro culture of the nematodes. The best medium for Steinernema glaseri production was obtained from concentrated homogenate of bovine liver and the nematode growth was highest at 80% bovine liver. In the co-culture of entomopathogenic nematode with its symbiont, the growth rate of nematodes was 2 times faster than that without its symbiont and the nematode concentration reached about $5.5\times10^4$/mL within 15 days.

• The Korean Journal of Pesticide Science
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• v.16 no.4
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• pp.267-272
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• 2012

Vitex trifolia L. is a full grown fruit of Vitex rotundifolia L. (Verbenaceae). It has been used for treating headache, dizziness, toothache and removal of fever as a traditional medicine in Korea. V. trifolia (500 g) were extracted three times with 80% aqueous MeOH at room temperature. The MeOH extract (38 g) was successively partitioned with n-hexane, EtOAc, n-BuOH and $H_2O$. Both n-hexane and EtOAc fractions showed more than 80% antifungal activity in vivo against several plant pathogens at 2000 ppm. Successive repeated silica gel, Sephadex LH-20, preparative TLC, and preparative HPLC of these fractions led to isolation of three compounds. Using mainly mass spectroscopy and nuclear magnatic resonance (NMR) spectroscopy, their chemical structures were determined as agnuside(1), chrysosplenol B(2), and artemetin(3). Compound 2 was isolated for the first time from V. trifolia. Study on in vitro and in vivo antifungal activities of the isolated compounds is in progress.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.49-49
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• 2009

마찰교반접합법은 특정한 회전수로 회전하는 용접 툴을 이용하여 접합하고자 하는 피접합재의 맞댄면에 삽입시킨 후 툴을 이동시키거나 혹은 시편을 견고하게 고정시킨 장치(backing plate)가 움직여 고상 상태에서 접합이 이루어진다. 알루미늄, 마그네슘 등 비교적 융점이 낮은 저융점 재료의 재료에 처음 적용이 되어 많은 연구가 활발히 진행되었고 타 용접방법에 비해 우수한 접합특성을 나타내었다. 최근 이러한 마찰교반접합은 이러한 저융점 재료를 넘어서 스틸, 타이타늄, 니켈 등과 같은 고융점 재료 등에 대한 적용이 늘어나고 있다. 마찰교반접합을 이용하여 이러한 고융점 재료의 접합 경우 내마모성 및 내열성 등의 내구성이 갖추어진 툴과 이러한 툴을 냉각시킬 수 있는 냉각 장치 등이 필요로 하나 경제적 측면이나 접합부의 우수한 특성 등을 고려 할 때 그 적용 및 발전 가능성이 매우 높다고 볼 수 있다. 최근 무공해 연료로 각광받고 있는 액화천연가스 (LNG)의 수요가 급증함에 따라 LNG 저장탱크 소재로 널리 사용되고 있는 9% Ni강의 수요 또한 증가하고 있는 상황이다. 하지만 9% Ni 강은 극저온용 소재로 용접부의 저온인성 ($-196^{\circ}C$)이 가장 중요하기 때문에 저온인성을 확보하고자 Inconel 계나 Hastelloy계 등의 니켈 기 합금을 용접재료로 사용하고 있으나 이러한 용접재료는 가격이 매우 고가이며 또한 용접 후 용접부의 강도가 낮다는 문제가 제기되고 있다. 또한 LNG 탱크 제작시 사용되는 용접법은 GTAW, SAW 및 SMAW 이지만 국내에서는 주로 SMAW에 의존하고 있는 실정인 관계로 보다 더 경제적인 용접 프로세스의 적용 가능성이 검토되고 있는 상황이다. 본 연구에서는 마찰교반용접을 이용하여 두께 4mm의 9% Ni 강에 대해 맞대기 마찰교반접합을 실시하였다. 툴 회전 속도 및 접합 속도를 고정한 상태에서 접합을 실시 하였으며 접합 시 툴은 $Si_3N_4$로 제작된 툴을 사용하였다. 접합 후 외관상태 점검, 미세조직 관찰, 경도, 인장 강도 및 저은 충격 측정 등의 실험을 실시하였고, 이러한 결과를 이용하여 미세조직과 기계적 특성과의 관련성을 조사하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.195-200
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• 2020

With the growing interest in fossil fuel depletion and environmental pollution, railroad cars operating in Korea are in progress as the conversion from diesel to electric vehicles expands. The photovoltaic system, which is applied as an example of the conversion of electric vehicles, is infinite and pollution-free, and can produce energy without generating hazards such as air pollution, noise, heat, and vibration, and maintain fuel transportation and power generation facilities. There is an advantage that is rarely needed. However, the amount of electricity produced depends on the amount of solar radiation by region, and the energy density is low due to the power generation of about 25㎡/ kWp, so a large installation area is required and the installation place has limited problems. In view of these problems, many studies have been applied to fuel cells in the railway field. In particular, the plan to link the fuel cell power generation system railroad power supply system must be linked to the power supply system that supplies power to the railroad, unlike solar and wind power. Therefore, it has a close relationship with railroad cars and the linkage method can vary greatly depending on the system topology. Therefore, in this paper, we study the validity through simulation modeling related to linkage analysis according to system topology.