• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.982-990
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• 2019

The interest of researchers and governments in exploiting tidal energy resources is increasing. Jangjuk strait is a place with high tidal energy density potential and is therefore appropriate for the constructing of a tidal turbine farm. In this study, a numerical approach is presented to evaluate the current flow and power potential in Jangjuk strait with an ADCIRC model. Then, the tidal field characteristics are utilized as input parameters for tidal resource calculation with an in-house program. The 1 MW scale tidal energy converter devices are employed and arranged in 4 layouts to investigate the annual energy yield as well as flow deficit due to the wake ef ect at the surveyed area. The best-performed array generates an annual energy yield up to 12.96 GWh/year (without considering the wake effect); this value is reduced by 0.16 GWh/year when accounting for the energy loss caused by the flow deficit. Moreover, by altering the turbine yaw angle during the flood and ebb tides, the impacts of this factor on the energy extraction are analyzed. This indicates that the turbine array attains the maximum tidal power when the turbine yaw angle is at 346° and 164° (clockwise, to the North) for the spring and neap tide in turns.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.49.1-49.1
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• 2011

집광채광 설비는 건축물의 조명에너지 절감 및 자연광의 실내 유입을 위해 적용 가능한 태양에너지설비로써 다른 신 재생 에너지 설비와 다르게 연간에너지생산에 대한 정량적 데이터가 아직까지 부재하다. 집광채광 설비의 설치효과를 판단하기 위해서는 집광채광 설비 설치에 따른 연간 에너지생산량 산출이 필요하며, 이를 위해서는 각 구성부분(집광부, 전송부 및 산광부)의 광전송 효율에 대한 데이터가 구축되어야 한다. 본 연구는 집광채광 설비의 효율 분석에 관한 첫 번째 단계로써 외부광속에 대한 집광부 통과 직후의 내부광속의 비율을 예측하였다. 국내에 보급된 집광채광 설비는 대부분 프리즘형과 광덕트형이며, 우선적으로 집광부 입사면의 경사각과 방위각이 다양하여 내부광속 산출방법론이 매우 복잡한 프리즘형을 분석대상으로 삼았다. 전일사량, 외부조도 및 집광부 내부조도가 측정되었으며, 외부광속으로부터 내부광속을 산출하는 공식을 유도하기 위해 천공상태에 따라 전일사량 측정치가 직산분리 되었다. Perez model과 Liu and Jordon에 의해 제시된 계산식과 입사면 및 집광부 면적을 고려하여 수평면 외부조도 측정치로부터 외부광속이 그리고 내부조도로부터 내부광속이 산출되었다. 입사면의 투과율이 동일하다는 전제 하에 천공상태에 따른 태양광 투과 비율을 도출한 결과, 담천공(Kt ${\leq}$ 0.3)에서 0.39, 부분담천공(0.3${\geq}$ 0.78)에서 1.0으로 나타났다. 도출된 투과비율을 외부광속에 적용하여 내부광속을 계산한 결과치와 측정치는 약 ${\pm}9%$ 정도의 차이를 보였다. 연간 기상데이터에 위와 같은 방법론이 적용되면 프리즘형 집광부의 연간 내부광속이 산출될 수 있다. 또한 기존 연구에서 제시된 발광효율 산출식과 일사 파장에 따른 시감도를 고려하면 매 시간별 외부조도도 산출이 가능하다. 일사량 측정치와 외부조도 측정치 사이의 상관관계를 분석한 결과 결정계수 $R^2$이 0.99인데 반해 일사량 측정치와 외부조도 계산치 사이의 상관관계 결정계수는 0.95로 측정치 보다 약간 작은 값을 갖는다. 이렇게 산출된 외부조도는 각 입사면의 면적을 반영하여 외부광속으로 변환되고, 앞서 산출된 천공상태별 투과비율이 적용됨으로써 내부광속이 도출될 수 있다. 이와 같은 집광부에 대한 연구를 바탕으로 향후 전송부와 산광부 효율을 도출하고 궁극적으로 집광채광 설비를 통해 실내에 전달되는 연간 빛에너지를 예측할 수 있을 것이다. 또한 본 연구의 방법론은 다른 형태의 집광채광 설비에도 적용이 가능할 것으로 판단되며, 국내 집광채광 설비의 연간 에너지생산량에 대한 폭 넓은 데이터 구축이 가능할 것으로 기대된다.

• Korean Journal of Environment and Ecology
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• v.15 no.2
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• pp.118-124
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• 2001

본 연구의 목적은 도식에 식재된 두 침엽수조인 소나무와 잣나무 단목의 연간 $CO_2$, $SO_2$, $NO_2$ 흡수 및 $O_2$ 생산을 계량화하는 것이다. 자연환경 조건하에서 운반형 적외선가스분석기로 연간 $CO_2$교환율을 측정하여 $CO_2$흡수 및 $O_2$ 생산량을 그리고 $CO_2$와 SO$_2$EH는 $NO_2$간 흡수속도비를 적용하여 $SO_2$ 및 $NO_2$흡수량을 각각 산정하였다. 흉고직경을 독립변수로 단목의 생장에 다른 연간 $CO_2$흡수 및 대기 정화량을 추정하는 활용 용이한 방정식을 유도하였다. 연구대상 수목 중, 흉고직경 20cm인 잣나무는 연간 양 35kg의 $CO_2$, 11g의 $SO_2$, 19g의 $NO_2$를 각각 흡수하였고 25kg의 $O_2$를 생산하였다. 동일 직경의 소나무는 유도한 방정식을 적용하면, 연간 약 30kg의 $CO_2$, 9g의$ SO_2$, 15g의 $NO_2$를 각각 흡수하였고 22kg의 $O_2$를 생산하였다. 생상기간 중 단위엽면적당 $CO_2$흡수량은 잣나무가 소나무보다 적었으나, 단목의 연간 $CO_2$흡수 및 대기정화량은 총엽면적의 차이로 잣나무가 동일 직경의 소나무보다 많았다. 본 연구결과는 도시 침엽수의 연간 대기정화 가치를 용이하게 계량화학고 도시공간내 수목식재의 환경적 중요성을 홍보하는데 활용될 수 있다.

• Journal of Korea Foresty Energy
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• v.25 no.1
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• pp.24-30
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• 2006

This study was conducted to understand the biomass and the energy content of 48-year-old Pinus densiflora stand planted in Mt. Wolak, Jecheon-si, Chungcheongbuk-do, Korea. The total biomass of aboveground was 138.14 ton/ha (87.3 ton/ha from stemwood, 41.43 ton/ha from live brances, and 9.41 ton/ha from leaves). Annual net production (ANP) of aboveground was 10.85 ton/ha/yr, and the ANP of stemwood, live branches, and leaves were 5.3 ton/ha/yr, 2.93 ton/ha/yr, and 2.62 ton/ha/yr, respectively. Energy content of aboveground was 2,981 GJ/ha, and annual energy accumulation was 239 GJ/ha/yr. The leaf area index (LAI) of P. densiflora stand was 6.58.

• Clean Technology
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• v.9 no.1
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• pp.23-28
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• 2003

The generation of food waste in Korea amounts to 4.10 million per year, which corresponds to 820,000 dry ton of organic waste. This has been used traditionally as animal feed or soil conditioner, but its efficacy has remained doubtful in recent years. In this study as an alternative we considered methane production by anaerobic treatment, which has an advantage of 200 million US dollars over aerobic methods. The production of methane amounts to $4.40{\times}10^8m^3$, 3.43% of $1.28{\times}10^8m^3$, total natural gas used in Korea. Furthermore the methane from household kitchen food waste amounts to 28.9% of the total gas used in the kitchen.

• Korean Journal of Environment and Ecology
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• v.17 no.4
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• pp.360-365
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• 2004

This study was carried out to estimate net fine root carbon production in Quercus variabilis natural stands in Chungiu area. Soil samples were taken in 0-30cm, 30-60cm, and 60-90cm soil depths from April to November using soil sampler. Fine root carbon biomass was higher in 0-30cm soil depth than the other soil depths. Net fine root carbon production (kg/㏊/yr) were 671kg in 0-30cm soil depth, 599kg in 30-60cm soil depth, and 479kg in 60-90cm soil depth, and 1749kg in 0-90cm soil depth. fine root turnover rates were 0.43 in 0-30cm soil depth, 0.96 in 30-60cmsoil depth, and 1.03 in 60-90cm soil depth. N, p, K, and Mg input into the soil (kg/㏊/yr) due to fine root turnover at 0-90cm soil depth in this study were 33.9kg, 1.8kg, 11.4kg and 20.1kg, respectively.

• Journal of the Korean association of regional geographers
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• v.12 no.6
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• pp.748-756
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• 2006

This study mainly deals with price behavior developed in a agricultural location model (or closed model) considering the production and demand aspects. The short-run situation of price and output is associated with the yearly fluctuation of yield from agricultural production. Demand is generally regarded as constant in the short-run because of being inelastic over short time. The long-run situation is associated with a period in which all related variables can be varied. Then a price behaviors from the two contrasting closed models have been further explored in the long-run economy. Agricultural price for each activity in the closed model is affected by change in agricultural production. Also, falling agricultural price is connected with lower rents and lower land values.

• Journal of IKEEE
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• v.23 no.2
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• pp.380-387
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• 2019

In recent years, solar energy PV/T research has been actively pursued by complementing solar heat acquisition and solar energy acquisition, and PV/T energy efficiency is generally excellent. In this study, the annual energy demand is calculated based on one building, and the energy production when PV / T installed on the roof and the energy production when PV are installed are compared and analyzed by simulation case. In conclusion, Busan which is the southern province in Korea, has the largest amount of energy generation, and introducing the concept of sharing surplus energy, excluding energy demand from generation. As a result, it can be supplied up to 3.3 households.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.560-571
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• 1994

A single station representative of the razor clam, Solen (Solen) strictus, on a macrotidal flat, Inchon, Korea was sampled at bimonthly intervals between May 1989 and July 1990 by using a can corer. Estimates of growth rate and annual production of this razor clam have been made using the techniques of cohort growth analysis. Growth rate and production were highest during the first year after spawning and recruitment. The annual production was $2.83g\;DWt/m^2/yr$, mean annual biomass $256.3\;g/w^20$, and a turnover time of 5.00 yea, giving an annual turnover rate (P/B) of $0.20\;yr^{-1}$. The total annual production in wet weight ($33.22g\;WWt/m^2/yr$) appeared to consist of water in live flesh($72.6\%$) and shell($18.9\%$), whereas the dry weight of the soft parts was $8.52\%$, the ash-free dry weight $5.4\%$, and the ash content $3.1\%$ of the total wet weight.

• The Korean Journal of Ecology
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• v.26 no.3
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• pp.129-134
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• 2003

Amounts of CO₂ fixed by net primary production and released by soil respiration were determined on big-cone pine plantation. Net primary production, which was determined by allometric method, was converted into CO₂. CO₂ evolution in forest ecosystems are mainly through soil and root respiration. In order to separate root respiration from soil respiration, root-free sites were made in stand. Litter removal sites were prepared to estimate CO₂ evolution through litter layer. Respiration was measured at every two weeks intervals from April 2001 through April 2002, and soil temperature and soil moisture were measured at the same time. Net primary production of this big-cone pine plantation was 25.7 t·ha/sup -1/·yr/sup -1/. The amount of CO₂ fixed by this plantation was 42.5 t CO₂·ha/sup -1/·yr/sup -1/, The amount of CO₂ released by soil respiration was 5.0 t CO₂·ha/sup -1/·yr/sup -1/. The relative contribution of root respiration and litter layer respiration to total respiration was 46% and 32%, respectively. Net amount of fixed CO₂ was 37.5 t CO₂·ha/sup -1/·yr/sup -1/ in this big-cone pine plantation. From this result, this big-cone pine plantation play a carbon sink source from the atmosphere.