• Tunnel and Underground Space
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• v.25 no.5
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• pp.435-449
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• 2015

Physical and microstructural properties of Pungchon and Maggol limestone were investigated quantitatively during 50 cycles of artificial freezing and thawing test. There were decrease in dry weight and P,S-wave velocity, and increase in absorption rate in both rock types. Porosity, pore volume, equivalent diameter, throat thickness and pore orientation were analyzed using X-ray computed tomography images. Porosity increased, and initiation and expansion of pores were investigated as weathering progresses. Physical and microstructural variation in Maggol limestone was larger than that of Pungchon limestone because Maggol limestone has more pores and microcracks at initial state. As this study analyzes physical and microstructural properties of rock specimens comprehensively, it can be applied to further rock weathering study and can be used as fundamental data of construction and resource development in cold regions.

• Korean Journal of Optics and Photonics
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• v.13 no.1
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• pp.1-8
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• 2002

Optical payloads for earth-observation satellites become bigger as the required resolution becomes finer. For example, the diameter of the primary mirror of IKONOS, which has ground sampling distances of 1m/4m in panchromatic/multi spectral bands, is about 700mm. As the size of optical payload becomes bigger, the light-weighting of the mirrors becomes more significant. This paper presents the FEM results of the following four mirror types of 300 m diameter under gravity release and temperature changes: flat back mirror, single arch mirror, double arch mirror, and honeycomb sandwich mirror. Furthermore, this paper extends the FEM results to larger mirrors up to the diameter of 1m based on a general scaling law and Valenete\`s equation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.1
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• pp.52-56
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• 1991

In 1986, at Cheju and Seoguipo, a sweet com hybrid, Golden Cross Bantam 70, was grown at 5 phosphate rates (0, 8, 16, 24 and 32 kg/l0a) to determine effects of phosphate rate on growth and yield of sweet com and to recommend the optimum phosphate rate for sweet com production in volcanic ash soils of Cheju province. Days to silking were shortened 1 to 2 days by phosphate application of more than l6kg/10a. Culm length, ear height and fresh stover yield/l0a did not differ between two locations, but linearly increased as phosphate rate was increased from 0 to 32kg/10a. Average length and weight of marketable ears were greater at Cheju than at Seoguipo and linearly increased as phosphate rate increased. The number of marketable ears per plant and per l0a did not differ between two locations, but quadratically increased as phosphate rate increased. The economic optimum phosphate rate estimated on the basis of the quadratic model, ranged 25.6 to 27.4kg/10a at various fertilizer-to-ear price ratios.

• Korean Journal of Plant Tissue Culture
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• v.21 no.2
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• pp.77-84
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• 1994

To assess the feasibility of anthocyanin production in cell cultures of Euphorbia splendens Bojer the role of sucrose in pigment production was investigated and pilot scale cultures were attempted to establish mass production system. And also, several instrumental analyses were conducted to identify the pigment extracted from cultured rolls. Anthocyanin production was promoted prominently with concenetrations of sucrose ranging from 3% to 9% while cell growth was maximized at 3% of sucrose . This suggested that high osmolarity of sucrose enhance pigment production. When cells were cultured in two types of bioreactor better cell growth was achieved with draft-type air lift bioreactor than impeller type bioreactor and the pigment productivity was reached to 2.2 mg/L/day. The major pigment extracted from cultured cells was characterized as cyanidin-3-glucoside.

• Journal of Forest and Environmental Science
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• v.11 no.1
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• pp.72-80
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• 1995

Altitudinal effects on the accumulation of O layer were examined for deciduous broad-leaved forests in the experimental forest of Kangwon National University. There found a marked increased towards the higher altitudes in the thickness of O layer. These trends could be observed conspicuously on the F2 and H layers. The relation between thickness (X, cm) and dry weight (Y, $kg/m^2$) of O layer was approximated by linear regression equations;Y($kg/m^2$ = aX(cm). The values of coefficient "a" for the F2, H and F2+H layers were 0.43, 0.61 and 0.53, respectively. Bulk densities of the accumulated organic matter estimated nearly to be $45g/dm^2$ in F2 layer, $60g/dm^2$ in H layer and $55g/dm^2$ in F2+H layer. The amount of O layer ranged from 13ton/ha for the forest at 280m in altitude to 41ton/ha for the upper forest at 710m in altitude. Among these total amount of the O layer, F1, F2 and H layer occupied to be 5~10ton/ha, 5~11ton/ha and 13~40ton/ha, respectively.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.3
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• pp.187-196
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• 2014

This paper suggests linearity enhancement algorithm to Ensure safety of Mobile Walker on Slope. Mobile Walker happens to get off track due to external forces from Walker's weight and the degree of the slope while slope driving. In order to compensate this, this research used the controller that estimates the external forces according to the slope of road surface and adjusts it to the motor output. Also, through comparisons between targeted rotational angular velocity which the user inputs and its velocity of the robot, algorithm was applied which applies a weight to each shaft. As a result of applying the proposed correction controller, it diverges in case of non-compensation experiments that deviates when moving, but it case of applying the ramp calibration algorithm, the deviation distance at max was within 10cm that it keeps safe driving, and change rate of deviation distance was also stabilized after 1m where no more changes occurred.

• JOURNAL OF ELECTRICAL WORLD
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• s.351
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• pp.89-94
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• 2006

에너지 해외의존도 97%, 무역의존도 70%인대한민국. 우리는하루220만배럴, 연간8억배럴이상을소비한다. 부존자원이 극도로 빈약한 우리나라가 나아가야 할 길은자명하다. 에너지 자원을 거의수입해 의존하다보니 이를고부가화 해 내수에 돌리면서 최우선으로 수출을 통해 온나라가 먹고 살고 있다해도 과언이아니다. 해외 에너지자원을 안정적으로 확보하는 것이 바로 국가경쟁력의 근원이 되는것은 어제오늘의 일이 아니다. 고유가 파고를 헤쳐나가야 한다는 절박한현실에서안정적인 에너지자원확보를 위한 정부의 해외자원분야 정책 및 민관전략이 올들어 의욕적으로 전개되고 있다. 우선정부는 자원개발 업무를 강화하기 위해 현재1과1팀의 자원개발조직을 보강하 고유전개발팀을 신설하는 등 모두3개팀으로 늘린다. 나아가 해외 자원확보에주력 산업 동반진출도 착착진행하고 있다. 국내 자원 개발 기업과 에너지관련기업, 해외진출기관등 14곳으로 구성된 ‘에너지산업해외진출협의회’도 최근 출범시켰다. 유전을탐사하거나 개발하는데 개인들도간접투자할수있는 ‘유전개발펀드’도 7월에 첫 선을 보인다. 약2000억원규모의이 시범펀드 도입 등을 통해 자원개발을 가속화,2013년까지원유-가스자주개발률을18%(원유15%, 가스30%)까지 끌어 올릴 계획이며 여기에16조원 신규투자가 소요 될 것으로보고있다. 이같은 일련의 공격적인 움직임은 단순히 돈을 주고 자원을 사오는 기존방식을 앞으로는과감히탈피,자원부국이 원하는 산업인프라등을 수주해제 공한뒤 그 대가로자원을 확보하는 총체적 자원확보전략에 무게를두겠다는 의지를 담고 있어 고무적이다. 여기에 다원유 등 수입원자재 가격이 급등세를 보이고있는 가운데 우리나라의 해외 자원개발사업이 활기를 띠고있다.석유공사는 민간기업들과 함께 지난해에만 예멘2곳 등 전세계 5개국9곳의 석유 및 천연가스 광구계약을체결, 올들어 최근참여사들과 함께 주주간계약 서명식을 갖고본격적인 사업을 추진 중이다. 광업진흥공사역시 SK네트웍스와제휴, 최근 전체 매장량이650만t으로 추정되는 중국 후난성의 아연광 탐사권을 획득, 합작 사설립계약을 체결한 것으로 알려지고 있다. 민간기업들도 해외자원분야진출이 활발하다. 기업들의 해외 자원개발을 위한 투자규모도 늘어 올해38개 해외 자원개발기업이 32개국 211개 사업에 모두31억달러를 투자할 계획인것으로 나타났다. 이에본지는 올해 들어서도 고유가의 지속으로 속증하고 있는에너지수입동향과 해외 자원 개발의 현실과 문제점, 개선방향, 나아가 최근 안전적인 자원확보를 위한 동향을 진단해본다.

• Journal of Plant Biotechnology
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• v.29 no.3
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• pp.209-215
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• 2002

Four kinds of kalosaponins from inner bark of Kalopanax pictus Nakai as a medicinal and edible timber tree species growing in Korea was analyzed by HPLC. A considerable range of variation in the contents was observed among population. The kalosaponins contents in inner bark from each population were the highest in the Mt. Barwang (30.37 mg/g on the dry weight basis) followed by Mt. Gariwang, Hanra II, Mangun, Paltan, and Hanra II population. Growth factors that might have influenced the contents of the kalosaponins were also examined. As both analysis results of partial correlation and multiple regression, the weight of inner bark and tree age were influenced the kalosaponin O contents. The kalosaponin B contents was influenced by both the weight of inner layer bark and annual mean DBH increment. The contents of kalosaponins appeared to be closely related to the inner bark characteristics.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.1-11
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• 2018

A system design and integrated design process for a space launch vehicle were established based on system engineering. With the mission design results for a given payload weight and trajectory, it is possible to perform optimal design by integrating each unit such as propulsion, weight estimation, and aerodynamic force after analysis, during in the system design process. The program is finally configured to verify that the designed vehicle can perform its mission through 3-DOF trajectory optimization simulation. Genetic algorithms are used as the optimization method, and the optimal design results of the variables and parameters to be considered during design are presented.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.1-9
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• 2022

Purpose: In this study, we used hydrophilic waterstop used in geosynthetics vertical barrier system to evaluate the performance of impermeability under sealing conditions. Method: ASTM D5887 and ASTM D6766 were applied to determine the capability of the connection during the geosynthetics vertical barrier system. Hydrophilic waterstop was saturated in each solution and the weight, thickness, and volume changes were analyzed over elapsed time. Hydrophilic waterstop was installed at the geosynthetics vertical barrier system connection to evaluate the permeability characteristics. Results: As the expansion reaction time of hydrophilic waterstop increased relatively under saline conditions, the decrease in permeability also showed a smaller decrease in fresh water. Furthermore, the method of engagement of the geosynthetics vertical barrier system showed somewhat better performance of the impermeability due to the large pressure resistance caused by the roll joint type than interlock type. Conclusion: In urban pollutants, which can estimate the outflow of pollutants such as oil storage facilities and industrial complexes, proactive response technologies that can prevent the contaminant diffusion can significantly reduce the damage.