한국의 경제 발전에 따라 양돈 사업의 규모가 커지고 대단지화 되면서, 생산성 향상과 높은 품질을 충족시키기 위해 축사시설의 체계적인 관리가 요구되고 있다. 그러나 효율성을 위해 밀집된 구조에서는 종종 여름철에 공기의 질이 나빠지고 온도가 높아지는 등의 문제를 일으킬 수 있다. 돼지는 저산소 및 고온에 매우 취약하기 때문에 생산성을 높이기 위한 환기 유지는 매우 중요하다. 이에 본 연구에서는 전산유체역학(CFD, computational fluid dynamics)을 이용하여 환기 시스템의 문제점 및 개선 사항을 분석하는 방법을 제안하였다. 유한체적법(FVM, finite volume method) 기반의 fluent 프로그램이 사용되었고 난류 모델로 RNG standard k-ε 모델을 사용하였다. 환기 시스템의 효율적인 설계를 위해 실제 단층의 단순 구조 양돈사와 다층의 대형 양돈사를 대상으로 다종물질이송(multispecies transport) 해석기법을 이용하여 환기 효율 및 성능을 분석하였으며, 개선된 시스템의 유동순환이 원활하게 이루어짐을 확인하였다.

Discarding juvenile fishes under girth 16 cm nearly equal to inner perimeter of codend mesh size collected by a cover net method in bottom trawl. The body size of the main five species (mackerel, horse mackerel, sea bream, melon seed and black throat seaperch) was measured for their body length, girth, weight, height and width and analyzed size selectivity. Frequency of penetrating fish as retention in a cover net was less than 40% of total number of juvenile discarding fish. The most of body length or girth of five species were significantly different between in the codend and in the cover net. The 50% selection girth in the cover net ranged 8-11 cm were smaller than those in the codend ranged 9-13 cm by the species respectively. The 50% selection body length was significantly related with the ratio of body height (H) by body width (W) both for in the codend or in the cover net while 50% selection girth was not significantly related with H/W. Furthermore 50% selection fish size by fish species between in the codend and in the cover net was not significantly different both in body length or girth. Therefore, the girth selectivity represented possibly as one unique value regarding fish body shape was considered as more useful method for multi-species catch in trawl.

Five species of the subfamily Cicadinae are found in urban areas at the center of the Korean peninsula, including Cryptotympana atrata, Hyalessa fuscata, Meimuna mongolica, Meimuna opalifera and Graptopsaltria nigrofuscata. Out of those species, the densities of C. atrata and H. fuscata are generally high in the urban area. I hypothesized that there is a vigorous acoustic interaction where two species are abundant. We tested this hypothesis by conducting the 24-h recording experiments in four localities: Gwacheon(GC), Jamsil(JS), Ewha University(EU) and Yangpyeong(YP). Based on the preliminary enumeration surveys of exuviae, GC and JS were designated as high density localities and EU and JS were as low density localities. The results of 24-h recordings and abiotic factor based on the multinomial logistic regression showed that C. atrata and H. fuscata were negatively correlated in high density area GC and JS. In JS and EU, the density of H. fuscata is close to each other. However, the probability of chorusing in JS is significantly lower than EU. This might be due to acoustic competition between two species. Moreover, we confirmed that the choruses of males of C. atrata produced loud choruses usually during the day when temperature high and males of H. fuscata produced calling song throughout the day but peaked in the morning and night. Consequently, multi-species cicada in different temporal pattern probably cannot be explained by only acoustic interaction but the combination of both abiotic and biotic factors probably constrain multi-species cicada to call together during the limited time windows.

This study aimed to examine the applicability of a portfolio approach to the ecosystem-based fisheries management targeting the large purse seine fishery. Most fisheries are targeting multispecies and species are biologically and technically interacted each other. It enables a portfolio approach to be applied to find optimal production of each species through expected returns and risk analyses. Under specific assumptions on the harvest quota by species, efficient risk-return frontiers were generated and they showed a combination of optimal production level. Comparisons between portfolio and actual production provided a useful information for targeting strategy and management. Results also showed the possibility of effective multispecies fisheries management by imposing constraints on each species such as total allowable catch quotas.

Five species of the subfamily Cicadinae are typically found in urban areas of central Korea, including Cryptotympana atrata, Graptopsaltria nigrofuscata, Hyalessa fuscata, Meimuna mongolica, and Meimuna opalifera. These species form multi-species choruses. We hypothesized that there is a negative relationship between dominance of choruses among cicada species. We tested this hypothesis by conducting the 24-h recording experiments in four localities: Gawcheon, Jamsil, Ewha University, and Yangpyeong. Based on the enumeration surveys of exuviae, the results of 24-h recordings showed that choruses of C. atrata and H. fuscata were negatively correlated with other in Jamsil and Ewha University, but were positively correlated with other in Gawcheon and Yangpyeong. Thus, it seemed unclear cicada species competed with each other negatively over. Males of C. atrata produced calling songs usually during the day at temperatures typically higher than 28 C°. However, males of H. fuscata produced calling songs throughout the day at a wide range of temperatures. As a result, the chorus of C. atrata dominated during the day, but that of H. fuscata in urban areas where the densities of C. atrata were sufficiently high.

수종간 독립성 검정결과 상수리-산초나무 외에는 지역별로 유의한 종간 상관이 서로 다르게 나타남으로써 수종간 생태적 지위의 공유관계는 수종간의 친화력뿐만 아니라 생육환경에 의한 영향도 큰 것으로 해석된다. 환경요인을 독립변수로 한 군집분석결과 물푸레나무는 화살나무, 노간주나무, 떡갈나무, 산초나무, 개옻나무 등과 같은 집단(물푸레나무-개옻나무 그룹)으로 분류되었으며, 음나무는 느릅나무, 당단풍, 병꽃나무, 물갬나무 등(음나무-느릅나무 그룹)과, 고로쇠나무는 두릅나무, 거제수나무, 서어나무 등과 같은 집단(고로쇠나무-거제수나무 그룹)으로 분류되었다. 환경요인과 군집간의 상관분석결과 지형, 해발고, 사면방향, 경사, 출현종수 등의 환경요인 중 지형과 해발고에 따른 영향을 많이 받는 것으로 분석되었다. 고로쇠나무-거제수나무 그룹은 해발고가 높은 계곡부~사면하부에 주로 분포하는 것으로 나타났으며, 음나무-느릅나무 그룹과 물푸레나무-개옻나무 그룹 수종들은 지형적인 적응력이 높아 넓은 면적에 산발적으로 분포하는 것으로 분석되었다.