• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.45-56
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• 1980

Farming density of oyster cultured in Hansan-Geoje Bay was studied to obtain the optimal farming density based on the biosedimentation analysis and the annual yield data from 1970 to 1979. Farming density of oyster extrapolated by means of pollution grade of sediment is significantly correlated to COD and phaeophytin content of the bottom mud of the bay. Pollution grade is linearly related to the number of oyster clusters suspended in the unit area. Optimal farming density was $0.12\;string/m^2$ in case of raft culture, and it was $0.12\;string/m^2$ in case of long-line culture. Farming density was well expressed by the number of strings per raft and the area covered by a raft. As strings per raft increased from 350 to 558, total yield from a raft increased and when occupied sea area per raft ranged from $1.000\;m^2\;to\;6,000\;m^2$, the yield per raft linearly increased as the area increased. This analysis suggests that the optimal density be 0.11 string per unit area $(m^2)$. As increasing the number of strings per $m^2$ the yield per string decreases, and this is well dipicted by a linear function. At this time the yield per unit area increases when the number of string increases up to the density of $0.13\;strings/m^2$. From the point of these three comprehensive analyses the optimal density was $0.11\~0.13\;string/m^2$ in case of raft culture and $0.25\;strings/m^2$ in case of long-line culture in Hansan-Geoje Bay. The maximum expected yield of oyster in Hansan-Geoje Bay is approximately 5,600 tons when maintained the string density at $0.11\~0.13\;string/m^2$.

• Journal of Plant Biology
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• v.35 no.4
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• pp.339-358
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• 1992

The bark morphology and anatomy of six species in Korean gymnosperms were examined with light and scanning electron microscopes. The species were Thuja orientalis (Cupressaceae), Ginkgo biloba (Ginkgoaceae), Cyeas revoluta (Cycadaceae), Pinus koraiensis (pinaceae), Taxus cuspidata (Taxaceae), Cryptomeria japoniea (Taxodiaceae). We described the bark features such as surface colour, thickness, depth of inner and outer bark. presense or absence and features of expansion tissue of ray, composition of periderm, and component cells of secondary phloem. The comparison with these features showed significant differences among all six species. Furthermore. it was suggested that sclereids types and sieve area shapes in sieve cells might be useful to the comparative morphological studies of gymnosperms.sperms.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.639-650
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• 2022

Abeliophyllum distichum Nakai, a rare plant with distylous characteristics, is native to certain parts of the Korean Peninsula. It is registered on the IUCN Red List of Threatened Species as a globally endangered plant. This study was conducted to establish an appropriate local conservation management plan suitable for future A. distichum populations by comparing and analyzing the flowering characteristics and population size according to distyly based on the results of quantitative surveys in 14 regions, including 8 areas with native populations of A. distichum and 6 natural monument populations. The number of individuals appearing in each population group was surveyed, and the flowering individuals were identified by style as being either pin or thrum flower types as they were being examined and recorded on the site. In total, 13,130 individuals of A. distichum (7,003 flowering and 6,127 non-flowering individuals) were recorded, but the balance of the number of pin- and thrum-flowered individuals in each population was not significant (p<0.05), indicating an imbalanced state. In particular, the Yeongdong (YD) population was very disproportionate compared to other populations, suggesting that its genetic diversity was low and the possibility of inbreeding was high. The average flowering and fruiting rates by management unit were much higher in the natural monument populations (89.2% and 55.3%, respectively) than in the natural habitat populations (39.0% and 8.5%, respectively). It may be due to a difference in reproductive growth resulting from light inflow into the forest caused by the upper crown closure. The area of occupation (AOO) of A. distichum on the Korean Peninsula covered an area of 23,224.5 m². Although the natural monument population was smaller than the natural habitat population, its density was higher, likely as a result of the periodic management of natural monument populations, where the installation of protective facilities in certain areas restricts population spread. Conservation of A. distichum populations requires removing the natural monument populations suspected of anthropogenic and genetic disturbances and expanding the conservation priority population by designating new protected areas. Although the habitats of natural monument populations are managed by the Cultural Heritage Administration and local governments, there are no agencies that are responsible for managing natural habitat populations. Therefore, institutional improvement in the overall management of A. distichum should be prioritized.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.1
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• pp.70-77
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• 2014

In this work, we studied basic characteristics of transmission lines employing various PSS (periodic strip structure) on silicon substrate for application to a miniaturization of RF components. According to the results, the transmission lines employing various PSS showed wavelength shorter than conventional coplanar waveguide due to their strong wave characteristics. Especially, with-contact structure was most effective for a miniaturization of RF component. Concretely, the size of the transmission line employing with-contact was only 4.39 % of the conventional coplanar waveguide, According to the bandwidth extraction result, the bandwidth of the transmission lines employing various PSS structures were wider than 384 GHz. Above results indicate that the transmission lines employing various PSS can be effectively used for application to a broadband and miniature RF component, and especially, with-contact is most effective for a miniaturization of RF components.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.04a
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• pp.183-184
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• 2000

도시화가 진행될수록 인구 집중과 고충 건물의 점유 증가를 초래하고 이로 인해 도심내 공장의 증가, 자동차의 폐열량 증가, 겨울철 연료와 여름철 냉방에 의한 에너지 사용량이 증가된다. 이때 방출된 열원으로 인해 도시 열섬의 강도는 커지게 된다. 단위면적에 대해 방출되는 열플럭스가 도시마다 큰 차이를 보이는데(Landsberg, 1981) 시드니 외곽부에 비해 도심내의 연간 에너지 사용량이 360배에 달한다는 것을 보였다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.220-221
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• 2000

도시화가 진행될수록 인구 집중과 고층 건물의 점유 증가를 초래하고 이로 인해 도심내 공장의 증가, 자동차의 폐열량 증가, 겨울철 연료와 여름철 냉방에 의한 에너지 사용량이 증가된다. 이때 방출된 열원으로 인해 인공열 배출량이 커지게 된다. 단위면적에 대해 방출되는 열플럭스가 도시마다 큰 차이를 보이는데(Landsberg, 1981) 시드니 외곽부에 비해 도심내의 연간 에너지 사용량이 360배에 달한다는 것을 보였다. (중략)

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1999.11a
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• pp.153-156
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• 1999

'98년말 현재 국내 양액재배 면적은 약 540ha로 '92년의 8.1ha에 비해 급격히 확대되고 있으며, 이 중 오이는 66ha로 12% 이상을 점유하고 있다. 오이의 경우 펄라이트를 이용한 고형배지경이 약 80%로 고형배지경의 대부분을 차지하고 있는데, 이는 근권환경의 안정성이 수경이나 분무경보다 높아 재배의 위험성을 경감시킬 수 있기 때문으로 생각된다. (중략)

• Journal of Distribution Research
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• v.5 no.2
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• pp.49-68
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• 2001

In this chapter, we summarize the results on the optimal location selection and present limitation and direction of research. In order to reach the objective, this study selected and tested the interaction model which obtains the value of co-ordinates on location selection through the optimization technique. This study used the original variables in the model, but the results indicated that there is difference in reality. In order to overcome this difference, this study peformed market survey and found the new variables (first data such as price, quality and assortment of goods, and the second data such as aggregate area, and area of shop, and the number of cars in the parking lot). Then this study determined an optimal variable by empirical analysis which compares an actual value of market share in 1988 with the market share yielded in the model. However, this study found the market share in each variables does not reflect a reality due to an assumption of λ-value in the model. In order to improve this, this study performed a sensitivity analysis which adds the λ value from 1.0 to 2.9 marginally. The analyzed result indicated the highest significance with the market share ratio in 1998 at λ of 1.0. Applying the weighted value to a variable from each of the first data and second data yielded the results that more variables from the first data coincided with the realistic rank on sales. Although this study have some limits and improvements, if a marketer uses this extended model, more significant results will be produced.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.121-127
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• 2002

당근은 미나리과에 속하는 직근성 채소로서 비타민A가 다량 함유된 건강식품으로 우리나라에 6,000㏊ 내외로 재배되고 있다. 재배지역은 우리나라 전체 재배면적 중에서 남제주군 지역이 44.5%, 경남 김해, 양산지역이 16.1%, 강원 평창지역이 11.1%를 점유하고 있으며 총 재배면적의 70% 이상이 주산단지 화되어 있어 기계화가 용이한 작목이다. 당근재배에 있어서 10a당 작업단계별 노동투하시간을 보면 전체 100.2시간으로 경운정지, 방제작업만 기계화가 이루어지고 대부분 인력에 의존하고 있는 실정이다. (중략)

• Tunnel and Underground Space
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• v.25 no.5
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• pp.470-486
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• 2015

Two-arch tunnels require minimal spacing between the 2 tunnels and thus occupy small amount of land compared to parallel tunnels. But it is rather expensive. The parallel tunnel is not as expensive, but it requires more land than 2-arch tunnels. This may cause a problem when there is a land shortage. The new design is to connect these two types of tunnels by another pair of parallel tunnels where the separation distance is gradually increasing. The applicability of this new design to the cases where rock condition is not even fair has to be verified since the width of the pillar between the connecting tunnels can be quite narrow. Therefore both two and three dimensional numerical analyses were conducted and pillar stability was examined for rock classes IV and V in two different ways. Results showed that this new design is still effective for poor rock conditions if central pillar is properly reinforced by tension bolts as long as overburden is less than five times of the tunnel diameter.