• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.74-84
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• 2009

The study aims that high quality recycled sand by wet manufacturing system can be used in practical way through basic material property. The basic material property test was done by 4 categories, dry manufacturing system (1) tandem and (2) parallel, wet manufacturing system (3) large capacity and (4) small capacity. RS-IV is the final production of (1) to (4) method, it is tested via KS F 2573 (recycled fine aggregate). RS-IV is satisfied with 4 items, those are absolute dry density, 0.08mm sieve throughput, clay lump amount, and organic impurity substance content. However, absorptivity item has problem in (1) and (2) method, (3) and (4) method are confirmed with norms 5% low. Also, the production quality of wet manufacturing system is better than dry manufacturing system in absolute dry density, absorptivity, 0.08mm sieve throughput, and clay lump amount.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.342-350
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• 2005

우리나라 서해안 중부, 경기만 일대는 강한 조석과 잘 발달된 해만으로 인해 천혜의 조력자원 보고로 알려져 있으나, 1980년대부터 서 남해 연안역에 대한 대규모 매립과 항만개발 등으로 조력개발입지 자체가 상실되고, 조석체계도 변화되고 있다. 한편 조력에너지는 기존의 화석연료를 대체할 수 있는 개발가능한 신 재생 에너지 중에서 거의 유일하게 대규모로 개발이 가능한 것으로 평가되고 있어 개발시 기대효과는 매우 클 것이다. 이에 우리나라 서해안의 조력자원 부존량을 파악하고 주요 후보지에 대한 개발타당성 검토를 통하여 주요 조력자원 후보지를 타 개발로부터 보호하고, 민간참여를 유도하여 조력에너지 개발을 활성화하고자 본 조사를 추진하였다. 한반도 조력자원 개발타당성 검토를 위하여 1) 서해안의 주요 지점에 대한 조석특성을 조사하였고, 2) 주요 조력자원 후보지 위치 및 영역을 설정하였으며, 3) 조석체계변화예측 수치모형실험을 실시하였고, 4) 후보지별 발전소 평면배치계획을 수립하였으며, 5) 후보지별 연간발전량과 개략공사비를 산출하여 6) 후보지별 개략타당성 검토를 수행하였다. 검토결과 우리나라 서해안의 조력개발 가능규모는 215만kW 정도이며, 주요 후보지를 모두 개발할 경우 연간 3,826GWh의 전기를 생산할 수 있을 것으로 조사되었다. 또한 연간발전량 대비 순공사비 비율에 따르면 만 입구가 좁아 개발 경제성 확보가 유리한 가로림만을 우선 추진하고, 이후 인천만, 천수만 순으로 개발하는 것이 유리한 것으로 나타났다.

• Economic and Environmental Geology
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• v.41 no.4
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• pp.443-451
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• 2008

Memon(1995) pointed out that the groundwater recharge from the precipitation is affected by various factors such as the occurrence, intensity, duration, and seasonal distribution of rainfall; air temperature, humidity, and wind velocity; the character and thickness of the soil layer above the water table; vegetated cover, soil moisture content, depth to the water table, topography; and land use. To reflect above factors, groundwater recharge in Chungju basin is computed by using the SWAT-K which is a longterm continuous watershed hydrologic model. Frequency analysis is adopted to evaluate the existing values of potential amount of groundwater development which is made by the 10 year drought frequency rainfall multiplied by recharge coefficient. In this work, the recharge rates of 10 year drought frequency in subbains were computed and compared with the existing values of potential amount of groundwater development. This process could point out the problems of existing precesses used for computing potential amount of groundwater development.

• Environmental and Resource Economics Review
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• v.25 no.4
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• pp.565-590
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• 2016

In accordance with the global efforts to reduce greenhouse gas emissions, Korean government submitted its INDC (Intended Nationally Determined Contribution) of 25.7% for domestic reduction and the total of 37% reduction by 2030 including the purchase of emission reduction permit from abroad. In this study, 25.7% reduction target is being evaluated to see its impact on domestic energy system using the integrated assessment model, GCAM (Global Change Assessment Model). Results show that electricity generation from fossil fuel technologies using coal and gas decrease by 28.0%, 13.5% while that of biomass, wind power, solar energy increase by 47.6%, 22.0% and 45.4%, respectively. It is worth noting that so called new technology such as USC (ultra supercritical power generation) does not contribute to achieving the emission reduction target and careful and quantitative analysis is required for such categorization in the future.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.198-203
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• 2020

Cracking due to material behavior like drying shrinkage easily occurs since tensile strength in concrete is very low at initial curing stage. In this paper, workability such as air content and slump was evaluated on CFC(Cellulose Fiber Concrete) with 0.0 ~ 2.0% of fiber addition, and the tests for tensile/compressive strength were performed. With increasing addition ratio of fiber, air content and slump kept similar level to 1.0kg/㎥ of addition ratio, and this trend was effective to 2 hours after mixing. Strength was enhanced with increasing addition ratio, which showed 7.0 ~ 9.0% for compressive strength and 7.0 ~ 22.0% for tensile strength, respectively. The tensile strength increased relatively more, which show the addition of cellulose fiber was very effective to crack resistance. The workability in CFC can be guaranteed for 2 hours in the following conditions like 2 minutes of mixing period and 1.0kg/㎥ of addition ratio of fiber.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.620-626
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• 1997

Annual biomasses of the hairtail, Trichiurus lepturus, were estimated from the biomass-based cohort analysis (Zhang, 1987), using data of annual catch in weight at age during $1970\~1988$ in Korean waters. Annual biomass of the hairtail was peaked at about 240,000 mt in 1975, and thereafter declined with a slight fluctuation. Adult biomass showed a peak in 1978 with about 55,000 mt. However, it has continuously decreased untill 1980 to the level of 9,000 mt and remained at this level till 1988. Age compositions of the hairtail in the 1980s differed greatly from those in the 1970s. The proportions of older hairtail (>4 years) were very low in the 1980s and even the biomasses of young hairtail $(1\~3\;years)$ were at a low evel in the 1980s compared with the level in 1970s. The 1973 and 1974 year classes appeared to be relatively dominant. The mean value of instantaneous rate of fishing mortality (F) in the 1980s was significantly different from that of the 1910s (P<0.05). Recruitment of the hairtail exhibited a similar trend with stock biomass until 1974, indicating the density-dependent Ricker curve.

• Resources Recycling
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• v.30 no.3
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• pp.47-54
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• 2021

Palladium present in colloidal-type plated spent catalyst solution that is used in electroless plating process has not been recovered but discharged as wastewater so far. Recyclig of paladium in colloidal-type plated spent catalyst solution is achieved with this study. This study presents the estimation of resource consumption and GHG emissions during the recycling and disposal of palladium in the plated spent catalyst solution using life cycle assessment. The reduction of resources and GHG are also estimated. Based on the palladium amount of 1 kg during disposal, the GHG emission amount was estimated to be 9.67E+03 kgCO₂eq., and the amount of resource consumption was 3.94E+01 kgSb-eq. However, GHG emission was 1.96E+03 kgCO₂eq., and the amount of resource consumption was 1.54E+01 kgSb-eq. during recycling. Considering the major substances affecting GHG emissions and amount of resource consumption, CO₂ was found to significantly affect GHG emissions, accounting for 91.42% in disposal and 98.37% in recycling. The major substance affecting the amount of resource consumption was hard coal, which accounted for 40.63% in disposal and 60.73% in recycling. Upon recycling 1 kg palladium, 8,967.17 kgCO₂eq. of greenhouse gas emission was reduced, while the resource consumption was reduced to 10.10 kg Sb-eq. In addition, the direct palladium resource reduction rate due to palladium recycling was 50%.

• Solar Energy
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• v.13 no.1
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• pp.67-74
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• 1993

Solar radiation intensity in Cheju-Do has been measured and analyzed to study the its characteristic and the possibility of the alternative energy, This work will also support the on-going project "Clean Enertopia in Cheju" which is strongly driven by government recently. The results of this project indicate that 1) Insolation in Cheju-Do is 10% lower than Southern coastal area. 2) A significant difference of insolation is observed between western and eastern part of Cheju-Do.

• Journal of Internet Computing and Services
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• v.18 no.4
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• pp.51-59
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• 2017

With the growth of Cloud computing, it is important to consider resource management techniques to minimize the overall costs of management. In cloud environments, each host's utilization and virtual machine's request based on user preferences are dynamic in nature. To solve this problem, efficient allocation method of virtual machines to hosts where the classification of virtual machines and hosts is undetermined should be studied. In reducing the number of active hosts to reduce energy consumption, thresholds can be implemented to migrate VMs to other hosts. By using Fuzzy logic in classifying resource requests of virtual machines and resource utilization of hosts, we proposed an adaptive VM allocation and migration approach. The allocation strategy classifies the VMs according to their resource request, then assigns it to the host with the lowest resource utilization. In migrating VMs from overutilized hosts, the resource utilization of each host was used to create an upper threshold. In selecting candidate VMs for migration, virtual machines that contributed to the high resource utilization in the host were chosen to be migrated. We evaluated our work through simulations and results show that our approach was significantly better compared to other VM allocation and Migration strategies.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.519-519
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• 2015

2007년 발간된 IPCC의 4차 평가보고서에서 자연재해, 환경, 해양, 농업, 생태계, 보건 등 다양한 부분에 미치는 기후변화의 영향에 대한 과학적 근거들이 제시되면서 기후변화는 현세기 범지구적인 화두로 대두되고 있다. 또한, 기후변화에 의한 지구 온난화는 대규모의 수문순환 과정에서의 변화들과 연관되어 담수자원은 기후변화에 대단히 취약하며 미래로 갈수록 악영향을 받을 것으로 6차 기술보고서에서 제시하고 있다. 특히 우리나라는 지구온난화가 전 지구적인 평균보다 급속하게 진행될 가능성이 높기 때문에 기후변화에 대한 담수자원 취약성이 더욱 클 것으로 예상된다. 따라서 지표수에 용수의존도가 높은 우리나라의 댐 저수지를 대상으로 기후변화에 따른 수환경 변화의 정확한 분석과 취약성 평가는 필수적이다. 본 연구에서는 SRES A1B 시나리오를 적용하여 기후변화가 주암호 저수지의 수환경 변화에 미치는 영향을 분석하였다. 지역스케일의 미래 기후시나리오 생산을 위해 인공신경망(Artificial Neural Network.,ANN)기법을 적용하여 예측인자(강우, 상대습도, 최고온도, 최저온도)에 대해 강우-유출모형에 적용이 가능한 지역스케일로 통계적 상세화를 수행하였으며, 이를 유역모델에 적용하여 저수지 유입부의 유출량 및 부하량을 예측하였다. 유역 모델의 결과를 토대로 저수지 운영모델에 저수지 유입부의 유출량을 적용하여 미래 기간의 방류량을 산정하였으며, 최종적으로 저수지 모델에 유입량, 유입부하량 및 방류량을 적용하여 저수지 내 오염 및 영양물질 순환 및 분포 예측을 통해서 기후변화가 저수지 수환경에 미치는 영향을 평가하였다. 기후변화 시나리오에 따른 상세기 후전망을 위해서 기후인자의 미래분석 기간은 (I)단계 구간(2011~2040년), (II)단계 구간(2041~2070년), (III) 단계 구간(2071~2100년)의 3개 구간으로 설정하여 수행하였으며, Baseline인 1991~2010년까지의 실측값과 모의 값을 비교하여 검증하였다. 강우량의 경우 Baseline 대비 미래로 갈수록 증가하는 것으로 전망되었으며, 2011년 대비 2100년에서 연강수량 6.4% 증가한 반면, 일최대강수량이 7.0% 증가하는 것으로 나타나 미래로 갈수록 집중호우의 발생가능성이 커질 것으로 예측되었다. 유역의 수문 수질변화 전망도 강수량 증가의 영향으로 주암댐으로 유입하는 총 유량이 Baseline 대비 증가 하였으며, 유사량 및 오염부하량도 증가하는 것으로 나타났다. 저수지 수환경 변화 예측결과 유입량이 증가함에 따라서 연평균 체류시간이 감소하였으며, 기온 및 유입수온 상승의 영향으로 (I)단계 구간대비 미래로 갈수록 상층 및 심층의 수온이 상승하는 것으로 나타났다. 연중 수온성층기간 역시 증가하는 것으로 나타났으며, 남조류는 (I)단계 구간 대비 (III)단계 구간으로 갈수록 출현시기가 빨라지며 농도 역시 증가하였다. 또한 풍수년, 평수년에 비해 갈수년에 남조류의 연평균농도 상승폭과 최고농도가 크게 나타나 미래로 갈수록 댐 유입량이 적은 해에 남조류로 인한 피해 발생 가능성이 높아질 것으로 예상된다.