인과순환구조 분석을 통한 큰고니 서식환경 유지방안 -을숙도를 중심으로-

최윤의 ( Yun Eui Choi ),유수진 ( Soojin You ),강성룡 ( Sung Ryong Kang ),최병구 ( Byoungkoo Choi ),전진형 ( Jinhyung Chon ) 한국환경생태학회 2015 한국환경생태학회지 Vol.29 No.3

본 연구에서는 을숙도 큰고니 서식지의 생태계 건강성 유지방안을 마련하기 위하여 시스템 사고를 통해 큰고니 서식환경 변화 현상에 대한 피드백 구조를 분석하였다. 을숙도 내 큰고니와 기타 수조류의 개체수에 대한 인과지도를 통해 을숙도 큰고니 개체수는 휴식환경 및 먹이환경 변화와 관계가 있음을 확인하였다. 큰고니의 휴식환경 인과지도에서는 탐조 및 탐방활동, 수위, 소음에 의한 휴식환경 변화가 큰고니 개체수에 영향을 미치는 것을 확인하였으며, 큰고니의 먹이환경 인과지도를 통해 담수의 면적, 수면동결, 을숙도 염분, 새섬매자기 밀도에 의한 먹이환경 변화가 큰고니 개체수에 영향을 미치는 것으로 확인 하였다. 마지막으로 통합인과지도를 통해 낙동강하굿둑 방류량과 건설행위가 큰고니의 휴식환경과 먹이환경에 영향을 미치는 변수임을 파악하였으며 큰고니 서식환경 관리를 위한 전략지점으로 선정하여 관리방안을 제시하였다. 연구의 결과는 장기적 관점에서 을숙도의 생태계 건강성을 유지를 위한 관리방안마련에 기여할 것이다. The goal of this study is to analyze the feedback structure of habitat changes of the Whooper Swan in Eulsukdo using system thinking to suggest a management plan for ecosystem health. Using the causal loop diagrams of population changes between Whooper Swan and other bird species in Eulsukdo, we found that the environmental changes in the roosting and foraging area affect the Whooper Swan’s population. The causal loopdiagrams of the Whooper Swan’s roosting area indicated that the environmental changes (e.g., water level, noise, bird watching, and other experience activities) may influence their population density variation. In addition, the casual loop diagrams of the Whooper Swan’s foraging area showed that the Whooper Swan’s population was affected by various variables that included area factors such as surface area of freshwater, frozen water, salinity, and density of Scirpus planiculmis. Furthermore, through the integrated causal loop diagram, cumulative discharge of Nakdong estuary weir and building activities were identified as the variables that affect the population of the Whooper Swan. Thus, we selected this area as the strategic point to establish a management plan for the Whooper Swan’s habitat. The results of this study will help in decision making of a long-term management plan for sustaining the environmental health of the ecosystem in Eulsukdo.

키 은닉 기법을 활용한 안전하고 신뢰성 있는 사물인터넷 디바이스 인증 기술

김병구(Byoungkoo Kim),윤승용(Seungyong Yoon),강유성(Yousung Kang),최두호(Dooho Choi) 한국정보보호학회 2020 情報保護學會誌 Vol.30 No.1

사물인터넷 환경으로 연결되는 디바이스 종류가 점점 다양해지고, 이를 통해 유통되고 처리되는 정보의 양이 절대적으로 증가함에 따라 여러 보안 이슈들도 함께 부각 되고 있다. 무엇보다도, 사물인터넷 기술은 우리 실생활에 직접 접목되기 때문에, 기존 사이버공간의 위험이 현실 세계로 전이 및 확대될 수 있다는 우려가 점차 증대되고 있다. 특히, 사물인터넷 기기들의 인증 및 데이터 보호에 필요한 키의 누출은 불법 복제 및 데이터 유출을 통한 경제적, 산업적 손실을 유발하고 있는 실정이다. 따라서, 본 논문에서는 이러한 보안 위협에 대응하기 위한 하드웨어 기반의 키 은닉 기술 및 소프트웨어 기반의 키 은닉 기술의 연구 동향에 대해서 살펴보고, 이를 활용한 사물인터넷 디바이스 인증기법을 제시한다. 이는 하드웨어 및 소프트웨어 기반의 키 은닉 기술을 적절히 접목함으로써, 여러 보안 취약점으로 인한 인증키 노출 위협을 근본적으로 차단하여 효과적이고 안전한 인증키 관리를 가능하게 한다. 즉, 본 논문은 다양한 키 은닉 기술에 대해서 설명하고, 이를 토대로 보다 안전하고 신뢰성 있는 사물인터넷 디바이스 인증 기술을 제공하고자 한다.

Effects of Experimental Drought on Soil Bacterial Community in a Larix Kaempferi Stand

Kim, Beomjeong,Choi, Byoungkoo Institute of Forest Science 2018 Journal of Forest Science Vol.34 No.3

Drought alters soil microorganisms; however, it is still not clear how soil microbes respond to severe drought conditions. In this study, the responses of soil bacterial community to experimental drought in a coniferous stand were examined. Six $6m{\times}6m$ plots with three replicates of control and drought treatments were delimited. PCR amplification and Illumina sequencing were conducted for cluster analysis of soil bacterial community and species richness and species diversity was analyzed. Along the 393 days of simulated drought from July 2016 to October 2017, soil bacterial species diversity slightly increased whereas species richness decreased in both control and roof plots. Moreover, soil bacterial species richness more decreased in roof plots than in controls. Combining these results, soil bacterial activity might have been altered by simulated drought.

A study on wettability according to the application of ultrathin palladium plating

Byeong Chan Choi,Byung-Jun Kim,Byoungkoo Kim,Hyoung Chan Kim 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1

Effects of Experimental Drought on Soil Bacterial Community in a Larix Kaempferi Stand

Beomjeong Kim,Byoungkoo Choi 강원대학교 산림과학연구소 2018 Journal of Forest Science Vol.34 No.3

Drought alters soil microorganisms; however, it is still not clear how soil microbes respond to severe drought conditions. In this study, the responses of soil bacterial community to experimental drought in a coniferous stand were examined. Six 6 m x 6 m plots with three replicates of control and drought treatments were delimited. PCR amplification and Illumina sequencing were conducted for cluster analysis of soil bacterial community and species richness and species diversity was analyzed. Along the 393 days of simulated drought from July 2016 to October 2017, soil bacterial species diversity slightly increased whereas species richness decreased in both control and roof plots. Moreover, soil bacterial species richness more decreased in roof plots than in controls. Combining these results, soil bacterial activity might have been altered by simulated drought.

Effects of Experimental Drought on Soil CO2 Efflux in a Larix Kaempferi Stand

Beomjeong Kim,Youngjo Yun,Byoungkoo Choi 강원대학교 산림과학연구소 2018 Journal of Forest Science Vol.34 No.3

Climate models forecast more frequent and a longer period of drought events which may impact forest soil carbon dynamics, thereby altering the soil respiration (SR) rate. We examine the simulated drought effects on soil CO2 effluxes from soil surface partitioning heterotrophic and autotrophic soil respiration sources. Three replicates of drought plots (6 x 6 m) were constructed with the same size of three control plots. We examined the relation between CO2 and soil temperature and soil moisture, each being measured at a soil depth of 15 cm. We also compared which factor affected CO2 efflux more under drought conditions. Total SR, autotrophic respiration (AR) and heterotrophic respiration (HR) were positively correlated with soil temperature (p < 0.05), and the relationships were stronger in roof plots than in control plots. Total SR, AR, and HR were negatively correlated only in roof plots, and the only HR showed a significant correlation (p < 0.05, r = -0.59). Soil respiration rates were more influenced by soil temperature than by soil moisture, and this relationship was more evident under drought conditions.

Effects of Experimental Drought on Soil CO₂ Efflux in a Larix Kaempferi Stand

Kim, Beomjeong,Yun, Youngjo,Choi, Byoungkoo Institute of Forest Science 2018 Journal of Forest Science Vol.34 No.3

Climate models forecast more frequent and a longer period of drought events which may impact forest soil carbon dynamics, thereby altering the soil respiration (SR) rate. We examine the simulated drought effects on soil $CO_2$ effluxes from soil surface partitioning heterotrophic and autotrophic soil respiration sources. Three replicates of drought plots ($6{\times}6m$) were constructed with the same size of three control plots. We examined the relation between $CO_2$ and soil temperature and soil moisture, each being measured at a soil depth of 15 cm. We also compared which factor affected $CO_2$ efflux more under drought conditions. Total SR, autotrophic respiration (AR) and heterotrophic respiration (HR) were positively correlated with soil temperature (p < 0.05), and the relationships were stronger in roof plots than in control plots. Total SR, AR, and HR were negatively correlated only in roof plots, and the only HR showed a significant correlation (p < 0.05, r = -0.59). Soil respiration rates were more influenced by soil temperature than by soil moisture, and this relationship was more evident under drought conditions.

HFCVD 방법을 이용한 다이아몬드 박막 증착에서의 Bias 효과

권민철(Mincheol Kweon),박홍준(Hongjun Bark),최병구(Byoungkoo Choi) 한국진공학회(ASCT) 1998 Applied Science and Convergence Technology Vol.7 No.2

HFCVD(Hot Filament Chemical Vapor Deposition)방법을 이용한 다이아몬드의 핵생성과 성장에 있어서, 인가한 직류 bias를 변수로 하여 핵생성 밀도와 증착율의 변화를 조사하였다. 반응압력 20torr, 메탄농도 1.0%, Filament 온도 2100℃ 그리고 Substrate 온도 980℃에서 증착 단계를 핵생성기와 성장기로 구분하고 각 단계마다 bias의 방향과 크기를 다르게 인가하면서 다이아몬드 박막을 증착하였다. Negative bias는 핵생성기에는 핵생성을 촉진시키지만 성장기에도 계속 인가하면 결정입자의 지속적인 성장을 방해하고 결정 구조를 비다이아몬드 성분으로 변화시키는 작용을 하여 박막의 morphology에 좋지 않은 영향을 주었다. Positive bias는 핵생성기와 성장기에서 모두 CH₄의 분해를 촉진시킨 결과 증착율의 향상을 가져왔다. 따라서 다이아몬드 박막의 증착시 핵생성기에서는 negative bias를 인가하고 성장기에서는 positive bias를 인가하는 것이 핵생성 밀도와 증착율의 향상에 효과적인 것으로 조사되었다. We investigated a bias effect for diamond films deposited by a HFCVD(Hot Filament Chemical Vapor Deposition) method using a methane-hydrogen gas mixture. During deposition total chamber pressure, methane concentration, filament temperature and substrate temperature was 20 torr, 1.0%, 2100℃ and 980℃ respectively. Also DC bias was applied during both the nucleation stage and the growth stage systematically. We found that negative bias enhanced the nucleation density at the nucleation stage, but it made a bad influence on the morphology of films at the growth stage. Positive bias enhanced the growth rate and resulted in a good morphology of films. Therefore we concluded that it was effective to apply the negative bias during the nucleation stage and then to switch into the positive bias during the growth stage in the fabrication of diamond films.

Microstructure and Tensile Properties of Ferritic Lightweight Steel Produced by Twin-Roll Casting

Yunik Kwon,Ji Hyun Hwang,Hee Chae Choi,T. T. T. Trang,Byoungkoo Kim,A. Zargaran,Nack J. Kim 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.1

Ferritic Fe–8Al–5Mn–0.1Nb–0.1C lightweight steel has been produced by twin-roll casting (TRC) process. The microstructures,in as-cast condition and during subsequent thermomechanical treatments, and tensile properties of the steel have beeninvestigated and compared to those of the similar steel produced with conventional ingot casting (IC). TRC significantly refinesthe microstructure of the steel in as-cast condition, with a formation of NbC and κ-carbide particles within matrix and alonggrain boundaries. NbC particles inhibit the grain coarsening during subsequent homogenization treatment, while κ-carbideparticles promote recrystallization during final annealing by particle-stimulated nucleation mechanism. Tensile properties ofthe TRC steel are comparable to those of the IC steel; however, such properties of the TRC steel have been achieved under amuch smaller number of processing steps, making TRC as an ideal alternative for the production of ferritic lightweight steels.

Experimental Throughfall Exclusion Studies on Forest Ecosystems: A Review

Park, Seunghyeon,Kim, Ikhyun,Kim, Beomjeong,Choi, Byoungkoo Institute of Forest Science 2019 Journal of Forest Science Vol.35 No.4

Climate change has been intensifying and affecting forest ecosystems. Over the years, the intensity and frequency of climate change have increased and the effects of climate change have been aggravating due to cumulative greenhouse gases such as CO₂, which has resulted in several negative consequences, drought being the main threat among all. Drought affects forest ecosystems directly and indirectly. Insufficient soil moisture, due to drought, may affect the growth of plants and soil respiration (SR), and soil temperature may increase because of desiccated soil. In addition, the mortality rate of plants and soil microorganisms increases. As a result, these effects could reduce forest productivity. Thus, in this article, we have presented various research studies on artificial drought using throughfall exclusion, and we have mainly focused on SR, which is significantly related to forest productivity. The research studies done worldwide were sorted as per the main groups of Köppen-Geiger climate classification and intensively reviewed, especially in tropical climates and temperate climates. We briefly reviewed the properties among the exclusion experiments about the temperate climate, which mostly includes Korean forests. Our review is not a proof of concept, but an assumption for adequate investigation of drought effects in the Korean forest.