• 환경영향평가
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• 제19권5호
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• pp.483-495
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• 2010

The passenger pigeon (Ectopistes migratorius) was a species of pigeon that was once the most common bird in North America. According to some ornithologists, the number of passenger pigeons is estimated as many as five to six billions at the time when the first Europeans arrived there. But this species became extinct in 1914. There were a multiplicity of causes in the extinction; first, the extension of telegraph lines and railroads into the Middle West of the USA beginning in 1850s, second, the loss of vast feeding, nesting, and roosting sites of the passenger pigeon due to the massive deforestation, third, the rapid population growth of the USA during nineteen century, fourth, the commercial exploitation of the species, and finally, the infirm and weak protective efforts. Some important lessons can be learned from the extinction of the passenger pigeon. First, it shows how much critical the public interest is for a successful conservational movement. Second, it illustrates the need for strong laws and practices in the protection of an endangered species from going extinct. Third, the fate of the passenger pigeon proves a very important principle in conservational biology. That is, for each species (bird or other animal) there is a minimum population to sustain the species. Ecologists generally believe that the extinction of the passenger pigeon was due to the loss of their numbers below the minimum owing to overexploitation.

• Asian Journal of Atmospheric Environment
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• 제4권1호
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• pp.55-61
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• 2010

The sensitivity of aerosol light extinction coefficient to the aerosol chemical composition change is estimated by (1) calculating the aerosol water content and chemical concentrations by a gas/particle equilibrium model and (2) calculating the aerosol light extinction coefficient by a Mie theory based optical model. The major chemical species are total (gas and particle phase) sulfuric acid, total nitric acid, and total ammonia which are based on the measurement data at Seoul and Gosan. At Seoul, since there were enough ammonia to neutralize both total sulfuric acid and total nitric acid, the dry ionic concentration is most sensitive to the variation of the total nitric acid level, while the total mass concentration (ionic concentration plus water content) and thus, the aerosol light extinction coefficient are primarily determined by the total sulfuric acid. At Gosan, since the concentration of ambient sulfuric acid was the highest among the inorganic species, sulfate salts determined aerosol hygroscopicity. Thus, both ionic and total mass concentration, and resultant aerosol light extinction coefficient are primarily determined by the sulfuric acid level.

• 한국환경복원기술학회지
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• 제19권2호
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• pp.95-107
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• 2016

The gold-spotted pond frog(Pelophylax chosenicus) classified as an Anura in Amphibia is sharply decreasing due to various changes of habitats environment, and designated as IUCN Red List Threatened species(VU; Vulnerable) internationally and domestic endangered species Class-II; therefore, it's in urgent need of the research on habitats restoration of the gold-spotted pond frog in order to prevent its extinction. This study was carried out to verify the effect after restoration by introducing the inhabitation elements deducted by the literature research and a field survey on the habitats for the gold-spotted pond frog in danger of regional extinction in the urban area of Ansan city, Gyeonggi-do, Korea. Accordingly, the capacity for bio-species was increased by expanding the area of habitats into $11,845m^2$, and securing the place for hibernation and corridors and discharge within the habitats, etc. As a result of the monitoring the number of individuals increased by 9.5 times as the reproductive success rate of the gold-spotted pond frog got higher, and by virtue of improvement in the habitats, biodiversity increased to 183 species(4 species of amphibians and reptiles, 4 species of mammals, 17 species of birds, 53 species of insects(terrestrial/Benthic), 4 species of fish, and 102 species of plants). It might be possible to verify the restoration effect of the habitats through continuous monitoring, and suggest the restoration model on the habitats for continuously survivable the gold-spotted pond frog in the urban area by deducting the matters to be improved.

• 환경생물
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• 제30권4호
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• pp.307-313
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• 2012

The Oriental White Stork (Ciconia boyciana) is a representative wetland species distributed across East Asia. The species has been declined to face the threat of species extinctions with estimation of at about 3000 individuals. In order to re-introduce the endangered storks in the field, we developed a baseline model using the program VORTEX, performed sensitivity test, and finally suggested an ideal model based on results of the sensitivity test. The baseline model predicted 12.5% extinction probability with mean time to first extinction of 82.0 year. Sensitivity test revealed that two demographic variables (first-year mortality and percent of adult female breeding) had the greatest impacts on population persistence. Thus, corrected model improved the population persistence, where the extinction probability decreased to 1.0% in 100 years by changing values of two variables within a range of applicable to the population. Our models for stork re-introduction suggest this population will be stable by improving first-year mortality and adult female fecundity.

• 대한환경공학회지
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• 제32권4호
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• pp.363-368
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• 2010

본 연구에서는 아데노신3인산의 측정을 통하여 음식물 쓰레기의 발효-소멸반응에서의 미생물이 발생 및 활성정도를 총괄할 수 있는 인자를 도출할 수 있었다. 목질바이오칩을 이용한 음식물 쓰레기의 발효-소멸에서 무게감량 및 유기물 분해율이 높아질수록 아데노신3인산의 농도가 증가하였다. 아데노신3인산은 목질바이오칩의 종류별 유기물 분해 및 무게 감량에 대한 성능 선택성 설정에 유용한 인자로 활용 기대된다.

• 대한기계학회논문집B
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• 제28권12호
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• pp.1557-1566
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• 2004

A flame extinction phenomenon is a typical unsteady process in combustion. Flame extinction is characterized by various physical phenomena, such as convection, diffusion, and the production of heat and mass. Flame extinction can be achieved by either increasing the strain rate or curvature, by diluting an inert gas or inhibitor, or by increasing the thermal or radiant energy loss. Though the extinction is an inherently transient process, steady and quasi-steady approaches have been used as useful tools for understanding the flame extinction phenomenon. Recently, unsteady characteristics of flames have been studied by many researchers, and various attempts have been made to understand unsteady flame behavior, by using various extinction processes. Representative parameters for describing flame, such as flame temperature, important species related to reactions, and chemi-luminescence of the flame have been used as criterions of flame extinction. In these works, verification of each parameter and establishing the proper criterions of the extinction has been very important. In this study, a time-dependent flame temperature and an OH radical concentration were measured using optical methods, and the instantaneous change of the flame luminosity was also measured using a high-speed ICCD (HICCD) camera. We compare the unsteady extinction points obtained by three different methods, and we discuss transient characteristics of maximum flame temperature and OH radical distribution near the extinction limit.

• 한국수정란이식학회:학술대회논문집
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• 한국수정란이식학회 2002년도 국제심포지엄
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• pp.56-62
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• 2002

The International Union for Conservation of Nature and Natural Resources (IUCN) considers the western/lowland bongo Tragelaphus eurycerus eurycerus to be a threatened species, and the eastern/mountain bongo Tragelaphus eurycerus isaaci an endangered species［1］. Although extinction is considered by many biologists to be a natural process during evolution, the exponential growth of the human population has drastically and prematurely reduced the numbers and genetic diversity of many species［2］. Species have evolved to adapt to a specific habitat or environment that meet their survival needs. Alteration or destruction of their habitat results in a species becoming incapable of adapting and hence becoming threatened with extinction. A widespread scientific and public consensus has emerged suggesting that governments should assign high priority to the maintenance of biological diversity via habitat preservation and management far species conservation［3］. Unfortunately, the loss of biological diversity far surpasses the available conservation resources and species are lost forever on a daily basis［4］. Notwithstanding the focus on habitat preservation and wildlife management, conservation biologists have also become increasingly interested in using the technologies of reproductive and developmental biology to help manage or rescue endangered species［5］.

• 대한기계학회논문집B
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• 제32권5호
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• pp.351-358
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• 2008

Extinction characteristics of hydrogen-air diffusion flames at various pressures are investigated numerically by adopting counterflow flame configuration as a model flamelet. Especially, effect of radiative heat loss on flame extinction is emphasized. Only gas-phase radiation is considered here and it is assumed that $H_2O$ is the only radiating species. Radiation term depends on flame thickness, temperature, $H_2O$ concentration, and pressure. From the calculated flame structures at various pressures, flame thickness decreases with pressure, but its gradient decreases at high pressure. Flame temperature and mole fraction of $H_2O$ increase slightly with pressure. Accordingly, as pressure increases, radiative heat loss becomes dominant. When radiative heat loss is considered, radiation-induced extinction is observed at low strain rate in addition to transport-induced extinction. As pressure increases, flammable region, where flame is sustained, shifts to the high-temperature region and then, shrunk to the point on the coordinate plane of flame temperature and strain rate. The present numerical results show that radiative heat loss can reduce the operating range of a combustor significantly.

• 한국산림과학회지
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• 제107권4호
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• pp.361-377
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• 2018

본 연구는 환경부의 멸종위기 야생생물의 지정이 지역 적색목록 방법을 올바르게 적용하였는지 보고서 내용을 전반적으로 검토하였다. IUCN의 지역 적색 평가에서는 평가 항목중 적용불가(NA)라는 범주가 존재한다. 해당 범주를 통해 전세계나 동아시아 전체에 매우 넓게 분포하는 종은 평가에서 제외하도록 명시하고 있다. 환경부에서 제시한 평가 결과물중 관속식물 377종이 언급되는데 이중 238종(63.1%)이 적용불가(NA)에 해당되며 일부는 분류학적 실체에 대한 논란의 여지가 되는 분류군(waiting)으로 13종(3.4%)이 확인된다. 환경부의 지역평가에 포함된 목록중 전 세계 평가 대상이 되는 소위 '진정 멸종위기' 분류군은 21종(9.3%)으로 매우 적었으며 앞으로 지역평가 시도가 가능한 분류군은 103종(27.3%)로 확인된다. 환경부의 멸종위기 야생생물인 관속식물 전체 목록중 66.6%는 지역 적색 평가로 부적절하거나 유보된다. 환경부의 종 목록과 평가의 문제점은 집단이 사라지는 '절멸'과 종이 사라지는 '멸종'의 용어상의 오용과 지역 적색평가의 그릇된 해석으로 혼란을 자초하고 있어 실제 IUCN의 지역 평가기준을 준용했다고 볼 수 없으며, 환경부에서 제시한 평가 조사방법도 적색목록을 평가하기 위한 자료 수집 방법론으로 보기가 어렵다. 지역 적색이라는 평가도 남한이라는 좁은 국가적 시각보다는 분포와 생물상을 고려하여 한반도와 접경지역인 러시아, 중국 대륙, 그리고 일본, 대만의 자료도 적극 수용한 새로운 '지역'의 개념 도입이 필요하다. 환경부의 올바른 지역 적색 평가를 위해서는 정확한 학명을 사용함과 동시에 주관적 잣대가 아닌 IUCN 지역 적색의 기준을 사용할 필요가 있다.

• 대한수학회논문집
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• 제21권4호
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• pp.701-717
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• 2006

The positive coexistence of a simple food chain model with ratio-dependent functional response and cross-diffusion is discussed. Especially, when a cross-diffusion is small enough, the existence of positive solutions of the system concerned can be expected. The extinction conditions for all three interacting species and for one or two of three species are studied. Moreover, when a cross-diffusion is sufficiently large, the extinction of prey species with cross-diffusion interaction to predator occurs. The method employed is the comparison argument for elliptic problem and fixed point theory in a positive cone on a Banach space.