• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.7
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• pp.35-44
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• 2004

In this study, a ventilation model was developed to determine a ventilation rate for the balance of heat, moisture and $CO_{2}$ in a mushroom house. Internal and external temperature, relative humidity and $CO_{2}$ concentration were measured and used to validate the ventilation model. The effects of various environmental factors on physiological responses of mushroom were also investigated. The verified model was simulated under the observed ventilation rates with a difference of$ 0.001{\~}0.065\;m^{3}{\cdot}S^{-1}$ (relative error of $0.3{\~}18.9\%$) when external temperature varied 22.5 to $24.8^{circ}C$ and average ventilation rates was $0.35m^{3}{\cdot}S^{-1}$. The optimal conditions for mushroom growth (internal temperature $22 ^{circ}C$, relative humidity $80\%$, $CO_{2}$ concentration 1,000 ppm) were used for the model application with external temperature, relative humidity and $CO_{2}$ concentration of $27.5{\~}33.5^{circ}C$, $60\%$, and 355 ppm, respectively. Thermal balance was a important factor for an optimum ventilation up to the external temperature of $32^{circ}C$, while $CO_{2}$ concentration balance was more important over $32^{circ}C$. This suggests that humidification for moisture balance is required to maintain temperature and $CO_{2}$ concentration at an optimal level by ventilation in a mushroom house.

• Journal of the Korean Academic Society of Industrial Cluster
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• v.2 no.1
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• pp.44-60
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• 2008

This paper analyses the relative efficiency and competitiveness of production structure for the industrial clusters(Ulsan, Changwon, Kumi, Wonjoo, Banwol & Siwha, Kwangwju, Gunsan) which had allocated in 2004 in Korea by the DEA approaches. The results show that except U1san, Wonjoo, the 5 industrial clusters have improved the relative efficiency in terms of input and output since they were allocated. And, the reason of the inefficiency for the 5 industrial clusters were not for the technical relationship but for the production scaling size. That is, by clustering for the industrial production firms, the economic effect came true throughout the production scaling size effects. Also, by the positioning approach for the production factors such as labor, capital, and R&D investment via production growth, the results show that Banwol & Siwha, Goomi clusters have effectively been managed, but Wonjoo, U1san and Gunsan are not.

• Journal of Environmental Science International
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• v.19 no.5
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• pp.543-548
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• 2010

This research was made to investigate the effects of burned, which is made in the early spring every year at Saebyeol-Oreum from 2003 to 2009, on changes in vegetation on the grassland. The results of analyzing the characteristics of the lay of the land showed that the proportion of the surface land that had the angle of azimuth and the angle of slope in the range of southeast $135^{\circ}{\sim}180^{\circ}$ accounting for 73.89% and $21^{\circ}{\sim}30^{\circ}$ accounting 58.33% of the entire surface land, respectively, was found to be highest. The results of the analysis showed that the relative importance value was found to be lowered from 27.07 in 2003 to 19.47 in 2009, and this can be attributable to the relative importance value of Artemisia japonica having been heightened from 7.07 in 2003 to 16.23 in 2009. The reason that the relative importance value of Artemisia japonica was found to be high is thought to be that vegetation on the surface land was removed by burned in the early spring and, due to this, the dry surface of soil and the high slope accelerated the soil erosion and could not provide proper environment of the growth and development for Imperata cylindrical and Miscanthus sinensis, so Imperata cylindrical and Miscanthus sinensis were excluded and Artemisia japonica whose importance value had been highest have flourished. Researches to maintain the current vegetation on the burned location of Saebyeol-Oreum and to adjust physical characteristics of soil to restore vegetation and the proper time and cycle of burned should be conducted.

• Korean Journal of Ichthyology
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• v.31 no.1
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• pp.54-61
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• 2019

A study on the diel activities and feeding habits of Pseudobagrus brevicorpus living in the Daegacheon Stream of Nakdonggang River was conducted in September 2017. Diel activity took place during the night, just after sunset and just before sunrise. Pseudobagrus brevicorpus swam in the middle depths, and when they found prey organisms, approached and consumed them immediately. Fish were divided by age into three groups. Prey organisms whose index of relative importance in the stomach contents exceeded 1% belonged to the orders Ephemeroptera (80.8%), Diptera (8.6%), and Trichoptera (8.5%). An index of relative importance by age showed that the Ephemeroptera are very important prey organisms, and the sizes of prey organisms increase with fish growth.

• Economic Analysis
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• v.26 no.3
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• pp.48-70
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• 2020

Using data from the Household Income and Expenditure Survey over the period 1994-2016, we estimate the coefficient of relative prudence in order to capture precautionary saving motive. To do this, we adopt a cohort approach, where we transform such microdata into sample cohort means. Together with initial income involving liquidity constraint, we estimate the relative prudence derived from the Euler equation. The two-stage least-squares (2SLS) between estimate of it obtained from the cohort panel data analysis is too small for the existence of precautionary saving motive, as in previous studies, while the 2SLS random effects estimate is so reasonable. Moreover, the liquidity-constrained cohorts tend to be more sensitive to uncertainty, relative to the unconstrained ones.

• Journal of the Korean Mathematical Society
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• v.43 no.5
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• pp.1129-1142
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• 2006

In this paper, we estimate area of tube in a CBA(0)-space with extendible geodesics. As its application, we obtain an upper bound of systole in a nonsimply connected space of nonpositive curvature. Also, we determine a relative growth of a ball in a CBA(0)-space to the corresponding ball in Euclidean plane.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.623-628
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• 1986

This paper reviews various CAD(Computer-Aided design) or DA(Design Automation) procedures for specification, design and verification of VLSI chips. The growth and widening of engineering achievements and applicational varieties in this revisited field has been truly explosive for the last five years. Recent trends in VLSI/CAD area and their possible implications on the future evolution of DA society are briefly touched upon. The relative importance of chip specification and design capability within the whole Korean electronics infrastructure in the future is explained with several possible suggestions for coping with upcoming difficulties already being seen in this challenging yet promising area.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.682-687
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• 2000

In this research the remaining service life of the concrete due to the steel corrosion was predicted by three cases; causing carbonation, using sea sand, using deicing salts. In case of deterioration by carbonation, effective carbonation depth, effective coverage depth and relative humidity are considered for predicting method. In case of using sea sand, predicting method is made of rust growth equation from polarization resistance method. In case of using deicing salts, predicting method is made of transformation of Fick's law. Three methods are very useful in predicting service life of concrete.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.167-168
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• 2002

서울 지역의 스모그 현상은 1차 오염물질에 의해 생기는 런던형 스모그 및 광화학 반응에 의한 LA형 스모그와는 다른 양상을 나타내고 있는데, 그 특성이 명확히 밝혀지지 않고 있다. 서울 지역의 스모그 특성을 체계적으로 밝혀내기 위해서는 스모그 현상에 대한 현장조사 연구뿐만 아니라 챔버 실험을 통한 스모그 생성과정에 대한 체계적인 연구도 필요하다. 시정장애(visibility reduction) 현상을 거치는 대기의 기상 특성을 보면 대부분 상대습도가 높은 조건이 낮에도 지속되는 경우가 대부분이다. (중략)

• Journal of Digital Convergence
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• v.7 no.1
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• pp.49-56
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• 2009

This paper provides in-depth analysis of internal and external factors that are important to food retailers' international market expansion, presenting Carrefour as a case. Nine sources of risks inherent in international retail market operation are explored and examined which are critical for Carrefour's international expansion. Key financial ratios of Du Pont System are used to assess Carrefour's performance in local market and relative to competitors. Carrefour's competitive advantages are also explored and compared with Wal-Mart, its major competitor in the international expansion.