• Fire Science and Engineering
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• v.16 no.3
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• pp.16-25
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• 2002

For Freon-23, a conventional extinguished agent regulated by Montreal Protocol and HFC-227ea, its alternative, the empirical equations were correlated in terms of saturated pressure, density, viscosity, enthalpy and surface tension. They were obtained by regression analysis from the experimental data in the literature. The empirical equations of saturated pressure were expressed as the second and third order function of temperature. The empirical equation of density was expressed as compressibility factor and saturated pressure by a function of temperature. The empirical equation of viscosity was formulated as a power function. Heat capacities as well as enthalpies were well fitted by empirical form of the second-order temperature. Finally, surface tension simply has linear function form in terms of temperature.

• Fire Science and Engineering
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• v.17 no.1
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• pp.26-32
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• 2003

Inert gases, Af, $N_2$, $CO_2$, as a Halon alternative, the empirical equations were correlated in terms of saturated pressure, density and viscosity, They were obtained by regression analysis from the experimental data in the literature. The empirical equations of saturated pressure were expressed as the second and third order function of temperature. The empirical equation for Ar and $N_2$ of density were expressed as the first order function of temperature. And $CO_2$ was expressed as the second and third order function of temperature. The empirical equation of viscosity was formulated as a power function with temperature. This empirical equations would allow us to predict pure component state.

• 한국해양학회지
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• v.18 no.2
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• pp.169-179
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• 1983

Distribution of soft-bottom macrobenthos en Masan Bay was studied in terms of seasonal changes in species composition, abundance, and diversity from August, 1980 to May, 1981. Of the 65 species ot benthic macrofauna observed, polychaete was the most dominant taxonomic group with 34 species, which accounted for 72% of the total number of benthic animals. Species richness and numerical abundance seemed to decrease from the outer Bay stations to the innermost bay station, where certain zoological groups such as crustaceans and echinoderms were eliminated. Based on the ecological indices calculated, the inner basins of the Masan Bay apparently receive high input levels of organic material derived from land drainage, domestic wastes, and industrial complex installed in Masan city and nearby urban area. Particularly, at two inner bay stations of the Masan Bay, these levels seemed to approach the limit of the degradative capacity of the muddy bottom ecosystem, and have significantly affected the characteristics and distfibution of the benthic macrofauna.

• Korean Journal of Ichthyology
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• v.17 no.4
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• pp.271-278
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• 2005

The ichthyofauna and fish community were studied in Miho Stream from May 2004 to August 2005. During the surveyed period 41 species belonging to 10 families were collected. Twelve of the species (29.3%) are endemic to Korea. Exotic fishes were Carassius cuvieri, Lepomis macrochirus, and Micropterus salmoides. Dominant species was Zacco platypus (54.7%). Comparing the present result with that of Son (1982), the indices of diversity,evenness and richness were lower and the dominance index was higher; Lampetra reissneri, Anguilla japonica, Acheilognathus macropterus, Coreoleuciscus splendidus, Pseudopungtungia nigra, Gobiobotia naktongensis, Lefua costata, Pseudobagrus koreanus, Monopterus albus and Iksookimia choii did not appear; Carassius auratus, Rhodeus uyekii, Rhodeus notatus, Acheilognathus lanceolatus, Pseudogobio esocinus, Hemibarbus longirostris, Microphysogobio yaluensis, Cobitis lutheri, Iksookimia koreensis, Pseudobagrus fulvidraco, and Rhinogobius brunneus, remarkably decreased, and Z. platypus, Pseudorasbora parva, and Squalidus gracilis majimae increased.

• Korean Journal of Ichthyology
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• v.31 no.2
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• pp.101-109
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• 2019

This study investigated the characteristics of fish communities at the Lake Yedang, in 2013 to 2014 and 2017. During the survey period, there were 29 species of 10 families collected from 3 survey stations. Of them, Cyprinidae occupied 34.5% (14 species), Bagridae, Gobiidae 10.3% (3 species), and Cobitidae, Centrachidae were 6.9% (2 species) in the number of species, respectively. Korean endemic species were 4 species (13.8%) Abbottina springeri, Cobitis nalbanti, Pseudobagrus koreanus, Odontobutis interrupta and accounted for a low rate. There were 3 species (10.3%) exotic species including Carassius cuvieri, Lepomis macrochirus, Micropterus salmoides. As a result of community analysis, dominant index was 0.45~1.00, diversity index was 0.19~2.30 and richness index was 0.41~1.94.

• Korean Journal of Organic Agriculture
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• v.26 no.4
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• pp.687-706
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• 2018

Organic agriculture is well known to be not only affecting the physical and chemical status of the soil but also closely connected to the biodiversity through complex community structure and ecological interactions. Current study monitored and analyzed the invertebrate biodiversity of organic and conventional paddy fields and upland fields from April, 2017 to August, 2017. Total of 680 species (with 14,371 individuals) were confirmed - more number of species were identified at the organic agriculture practicing fields. According to the various indices analysis, organic paddy field showed about 40% higher diversity index, while organic upland field showed about 10% higher diversity index. Richness index at organic paddy field was 60% higher compared to conventional paddy field, while organic upland field showed 40% higher value. Dominance and evenness index at conventional agriculture practicing fields were low, which possibly indicate at least partial dominance phenomenon. Hemipteran, dipteran and aranean species showed highest diversity in all fields, while dipteran, hemipteran, aranean and coleopteran species had highest diversity in conventional agriculture practicing fields.

• Journal of Forest and Environmental Science
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• v.16 no.1
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• pp.1-16
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• 2000

This study was carried out to examine the process of plant succession through vegetation invasion and to select appropriate endemic plant species for rapid stabilization and good visual effect on cut-slopes of forest roads. Establishing total of sixty $1m{\times}1m$ sample plots. fifteen for each forest road constructed in the year of '93 (six-year-old), '95(four-year-old), '97(two-year-old), and '98(one-year-old), the ecological attributes of invading vegetation on cut-slopes were analyzed. The results are summarized as follows: 1. The rate of vegetation coverage was highly associated with soil hardness and aspect of cut-slope. Higher rate of vegetation coverage was caused by larger number of invading plant species. 2. The dominant woody species were Rubus crataegifolius, Rhus chinensis, Lespedeza bicolor, Salix hulteni, Alnus hirsuta, and Pinus densiflora. The visual attractive for the fruit of Rubus crataegifolius and the autumn coloration of Rhus chinensis was noteworthy. The dominant herbaceous species were Youngia sonchifolia, Spodiopogon sibiricus, and Lysimachia clethroides in all study forest roads. Spring flower of Potentilla freyniana and Viola rossii: summer flower of Lysimachia clethroides, Commelina communis, Glycine soja. Persicaria sieboldi, and Oenothera odorata: and autumn flower of Artemisia stolonifera and Impatiens textori were abundant and remarkable. 3. The diversity index of woody species tended to be increased as years passed after construction, and that of herbaceous species were decreased. 4. The dominance of Th of dormancy form was early high in the first year of construction, getting decreased thereafter. And that of MM + M + N was increased as years passed after construction. but that of Ch+H+G+Th+HH was decreased. 5. The degrees of succession were estimated by 359, 111, 97, and 87 for the construction year of '93, '95, '97, and '98. respectively, increased as years passed after construction.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.3
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• pp.298-304
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• 1986

The friction reduction by dilute polymer solutions was investigated experimentally in journal bearings. Flow pattern visualization and torque measurements were performed for a concentric case (.epsilon.=0). The effects of polymer concentration, bearing clearance, and polymer molecular weight on friction reduction were examined. The frictional torque and the intensity of vortices of the case of polymer solution were reduced compared with those of base oil only.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1990.11a
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• pp.1-15
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• 1990

엔진 성능의 향상에 맞추고 에너지 절약을 위한 방법으로써 엔진 오일의 마찰 마모 특성등 오일의 성능을 높이려는 노력이 꾸준히 시도되고 있다. 특히 마찰력 손실을 감소기키기 위해서 낮은 마찰특성을 갖도록 몰리브데늄(Mo)을 유용성인 금속 착화합물로 만든 Mo-DTP를 제조하여 현재 첨가제로 널리 사용되는 Zn-DTP와 대체시키려는 연구가 활발하고 최근엠 많은 논문이 발표되고 있다. 또 일부 윤활유 제조 회사에서는 몰리브레늄을 첨가 시키는 등 제품 기술을 향상시켜 오일 교환의 기간이나 자동차 주행 거리를 대폭적으로 늘려줄 수 있는 상품도 생산되고 있다. 윤활 첨가제로써 Mo-DTP를 Zn-DTP와 대체시켜 기유에 혼합한 경우에는 마찰 감소 기능이 매우 향상 되었고 내 마모성도 비교적 좋으나 산화 억제 능력이 부족하고 온도의 상승에 따른 점도 지수의 증가도 비교적 크다는 단점을 갖고 있음이 발표된바 있다. 따라서 Mo-DTP의 단점을 보완하려는 연구가 필요되고 그의 한 방법으로써 현재 첨가제로 가장 많이 사용되는 Zn-DTP와 혼합하여 첨가 하였을 경우에 대한 연구를 하였다. 이때 기본 윤활유에 Mo-DTP와 Zn-DTP를 적당한 혼합 비율로 첨가하고 하중, 온도를 변화 시키면서 마찰, 마모등의 성질고 산화 안정성 및 마모 입자 분석 등 전반적인 윤활유로써의 특성을 살펴 보았다.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2011.04a
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• pp.98-103
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• 2011

도심하천에서 채집된 어류는 총 7과 17종 315개체가 확인되었으며, 자연하천에서 채집된 어류는 6과 21종 1,033 개체가 조사되었다. 도심하천에서 출현한 한국 고유종은 치리(Hemiculter eigenmanni)와 얼룩동사리(Odontobutis interrupta) 2종(11.8%)이었으며, 생태계교란야생동물에 속하는 종인 배스(Micropterus salmoides)가 폐쇄형 하도습지에서 출현하였다. 자연하천에서 출현한 한국고유종은 쉬리 (C. splendidus), 배가사리(Microphysogobio longidorsalis) 등 총 13종(61.9%)으로 고유종의 빈도가 높았고, 멸종위기 II급에 속하는 종인 묵납자루(A. signifer)와 가는돌고기(Pseudopungtungia tenuicorpa) 등 2종(9.5%)이 조사되었다. 두 하천의 군집분석을 비교한 결과 도심하천이 자연하천에 비해 우점도와 균등도 지수가 높게 나왔다. 이와 같은 결과는 도심하천과 자연하천이 같은 유형의 서식처이지만 도심하천의 경우 양안 수변대와 제방구축, 하천정비, 고수부지의 시멘트화 등의 원인과 오염원의 유입, 풍부한유기물 때문인 것으로 판단된다.