• 토지주택연구
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• 제3권1호
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• pp.89-96
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• 2012

본 연구는 공동주택에서 하이브리드 환기시스템의 적용성을 검토하고, 하이브리드 환기시스템의 성능을 향상하기 위해 CFD시뮬레이션을 이용하여 설계방안을 제시하고자 하였다. 연구대상으로는 전용 $51m^2$, $84m^2$의 공동주택을 선정하였으며, 하이브리드 환기시스템은 창틀자연급기와 각실을 덕트로 연결하여 배기하는 시스템(Hybrid 1)과 창틀자연급기와 욕실 거실배기가 혼합된 시스템(Hybrid 2)을 적용하였다. 이때 각 시스템별 배기구의 위치를 변수로 하여 CFD를 수행하였다. $51m^2$, $84m^2$ 모두 Hybrid 2가 Hybrid 1보다 환기효율이 우수한 것으로 나타났으며, 평균공기연령 또한 낮은 것으로 나타났다. Hybrid 1의 경우, 덕트 배기구의 위치가 각 실 입구에 설치하는 것보다 실 안쪽 모서리에 설치하여 기류이동을 많이 유발할 수 있는 유형이 효과적인 것으로 나타났다. Hybrid 2의 경우, 욕실 고정압팬에 덕트를 연결하여 거실중심에 배기구를 설치하는 시스템이 환기효율이 가장 우수한 것으로 나타났다. 그러나 $51m^2$의 경우 Hybrid 2가 Hybrid 1보다 20%의 향상된 환기효율을 나타낸 반면, $84m^2$의 경우는 14%의 향상된 환기효율을 나타내 공동주택 규모에 따른 적정한 하이브리드 환기시스템에 대한 검토가 필요하다.

• 토지주택연구
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• 제4권1호
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• pp.119-124
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• 2013

나노여과막은 일반적으로 하전막이며, 용질의 하전성, 막과의 상호작용에 의해서 특징 있는 분리특성을 보인다. 본 연구에서는 나노여과막에 의한 폐수 중의 중금속류의 제거에 미치는 하전특성을 조사했다. 크롬(Cr), 철(Fe), 구리(Cu), 아연(Zn), 비소(As), 주석(Sn), 납(Pb)을 각각 0.1mg/L 첨가한 모의폐수를 제조하여 나노여과막(a)와 나노여과막(b)를 이용하여 운전압력 0.24MPa, 온도 $25^{\circ}C$에서 여과실험을 수행하였다. 그 결과, 나노여과막(a)와 나노여과막(b)에 의한 염소 이온의 제거율은 12.8%, 3.5%였고, 황산이온의 제거율은 78%, 9.3%였고 TOC의 제거율은 70.4%, 26.2%이었다. 한편, 중금속의 제거율은 나노여과막(a)의 경우 크롬(Cr) 92.5%, 철(Fe) 90.9%, 구리(Cu) 93.1%, 아연(Zn) 92.6%, 비소(As) 74.6%, 주석(Sn) 97.3%, 납(Pb) 93.4%이었고, 나노여과막(b)의 경우는 크롬(Cr) 69.9%, 철(Fe) 84.6%, 구리(Cu) 87.0%, 아연(Zn) 73.3%, 비소(As) 15.2%, 주석(Sn) 80.1%, 납(Pb) 87.7%이었다. 여기서, 나노여과(a), 나노여과(b)의 경우 공통적으로 크롬, 철, 동, 아연, 주석, 납에 비하여 비소의 제거율은 상대적 낮았다. 상기 실험결과에서 폐수 중에 다량 함유되는 염소이온 및 황산이온에 대한 중금속류의 분리계수와 이온성분의 수중에서의 활동정도를 나타내는 인자인 이온 몰 전도도로 해석할 수 있었다. 그 결과, 몰 전도도 비가 큰 중금속 이온일수록, 나노여과막에 의한 중금속 이온의 제거율이 높아지는 경향을 알 수 있었다.

• 대한환경공학회지
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• 제36권10호
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• pp.691-697
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• 2014

도시 하천의 지속가능한 관리를 위해서는 적절한 유역 관리가 필수적이다. 현재 대전 관평천의 상류 유역은 그린벨트지역으로 보호되어 있으나 해당 유역의 농경활동이나 도로공사 등 인위적인 요인으로 인해 관평천은 지속적인 환경문제를 나타내고 있다. 관평천의 적절한 종합 수자원 관리 계획을 수립하기 위해서는 하천의 수질문제 뿐만 아니라 유량 문제도 의미있게 고려되는 것이 바람직하다. 본 연구에서는 관평천 유역에 대해 대표적인 도시형 강우 유출 모형인 storm water management model (SWMM)을 구축하고 실측자료를 활용하여 보정 및 검증을 실시하고 향후 임의의 강우 조건에 대해 하천 주요지점의 유량 및 수질을 예측할 수 있도록 하였다. 유량 보정은 상관계수($R^2$)가 0.9 이상의 양호한 수준으로 수행되었으나 수질 보정은 상대적으로 오차가 큰($0.67{\leq}R^2{\leq}0.87$) 것으로 나타났다. SWMM 모델을 이용하여 상류 유역이 개발되었을 경우 환경에 영향을 적게 미치는 LID (low impact development) 기법을 적용하는 가상의 시나리오를 구성하여 비교할 수 있는 방법을 구축하였다. 본 연구결과는 향후 관평천 상류지역을 개발하거나 환경관련 관리 계획을 수립할 경우, LID기법을 포함한 합리적인 수자원 기법 선택에 많은 도움을 제공할 수 있을 것으로 기대된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.11-14
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• 2007

Noise level and Airflow amount of a kitchen hood are affected by the conditions of airflow path. Thus this study is expected to be used as a basic reference in designing airflow path of apartment housing throughout analysing changes in noise level and airflow amount from the various conditions of airflow path. Noise level generated by the kitchen hood is estimated in a kitchen and a living room of two constructed apartment houses, and an experiment is conducted in an half anechoic chamber to analyze noise level and airflow amount by the different length, diameter and number of windings of a round shaped soft duct which is connected to the kitchen hood. The measured results in apartment houses show that the noise level in both apartments exceeds the NC standard greatly in living spaces. In apartment A, a regular apartment house, the noise level was $NC-65{\sim}75$, $NC-45{\sim}60$ and NC-70, NC-45 in the kitchen and living room with an operation of kitchen hood in 1 and 3 stages. In apartment B, an apartment complex, the noise level was NC-55 and NC-60 in the kitchen and living room with an operation of kitchen hood in 3 stages. In particular, there was an increase of noise level at 125Hz-band resulted from an amplification of sound, which requires adequate measures in noise reduction. The results measured in Half anechoic chamber show 99% of airflow amount increase with the modification of a duct' s diameter from ${\Phi}$ 100mm to ${\Phi}$ 125mm, 37% of airflow amount increase with the modification of a duct' s diameter from ${\Phi}$ 125mm to ${\Phi}$ 150mm, and 173% of airflow amount increase with the modification of a duct' s diameter from ${\Phi}$ l00mm to ${\Phi}$ 150mm. The noise level was lower than the level measured in apartment housing about 20 in NC-value and 11.4 in dB(A)-value, which was interpreted as the effect of the load by the pressure condition at the rear end of the duct. Also, an amplification of sound in 125Hz-band influenced NC-value considerably, therefore effective measure is needed.

• 한국음향학회지
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• 제42권6호
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• pp.565-571
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• 2023

사후확인제 도입으로 현장에서의 바닥충격음 성능 측정이 의무화되고, 평가 방법이 변경되었다. 제도 변화에 따른 바닥충격음 성능 변화를 추적하기 위해서는 변경된 평가방법에 따라 중량충격음 특성이 어떻게 나타나는지에 대한 연구가 필요하다. 본 연구에서는 평면과 바닥구조가 동일한 하나의 아파트 건물에 위치한 59세대를 대상으로 충격원 및 평가지표에 따라 단일수치평가량을 결정하는 주파수 대역의 기여율을 분석하였다. 단일수치평가량에 따른 주파수대역별 기여도 산출방법이 상이하여 단순 비교는 어려우나, 사후확인제 도입 이전 평가방법(뱅머신 측정 및 L'_i,Fmax,AW으로 평가)에서는 63 Hz가 미치는 기여율은 평균 80.8 %로 나타났으며, 125 Hz가 미치는 기여율은 평균 19.2 %으로 나타났다. 현행 평가방법(고무공 측정 및 L'_iA,Fmax으로 평가) 에서는 기여율은 50 Hz ~ 80 Hz에서 평균 33.1 %, 100 Hz ~ 160 Hz에서 평균 58.7 %, 200 Hz ~ 315 Hz에서 평균 6.9 %, 400 Hz ~ 630 Hz에서 평균 1.3 %으로, 63 Hz 대역의 기여도가 낮아진 것으로 나타났다. 이 결과는 대상 공동주택에 대한 사례 분석 내용으로, 더 다양한 공동주택에 대한 측정 데이터를 분석할 필요가 있다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 사면안정학술발표회
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• pp.65-81
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• 2003

During the last few decades in Korea, the development of hillside or mountain areas has rapidly increased for infrastructure construction such as railroads, highways and housing. Many landslides have occurred during these constructions. Also, the amount and scale of damage caused by landslides have increased every year. In the case of Far East Asia including Korea, the damage of landslides is consequently reported during the wet season. In this paper, the effect of stabilizing piles on slope stability is checked and the behavior of slope soil and piles are observed throughout the year by field measurements in the large-scale cut slopes. In particular a large-scale cut slope situated on the construction site for the express highway in Donghae, Korea. First of all, The behavior of the slope soil was measured by inclinometers during slope modification. Landslides occurred in this area due to the soil cutting for slope modification. The horizontal deformations of slope soil gradually increased and rapidly decreased at depth of sliding surface indicating that the depth of sliding surface below the ground surface can be predicted. On the basis of being able to predict the depth of the sliding surface, stabilizing piles were designed and constructed in this slope. To ensure the stability of the reinforced slope using stabilizing piles, an instrumentation system was installed. The maximum deflection of piles is measured at the pile head and it is noted that the piles deform like deflection on a cantilever beam. The maximum bending stress of piles is measured at the soil layer. The pile above the soil layer is subjected to lateral earth pressure due to driving force of the slope, while pile below soil layer is subjected to subgrade reaction against pile deflection. As a result of research, the effect and applicability of stabilizing piles in large-scale cut slopes could be confirmed sufficiently.

• Asian-Australasian Journal of Animal Sciences
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• 제9권6호
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• pp.615-635
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• 1996

The animal industry must be environmentally sound to ensure its long-term sustainable growth. Livestock wastes mostly manure, can be a valuable resource as well as a potential hazard to environment. The first option of manure management is developing an 'environmentally sound' feeding program and feeds so there are less excreted nutrients that need to be managed. Once the manure is produced it can be best utilized as a fertilizer of a soil conditioner. In many countries the amount of manure that can be spread on land depends on the nutrient requirements of the crop being grown. The laws specify maximum application rates and not animal stocking rates. Farmer who reduce the N and P component of manure can release pressure on the environment without having to reduce the number of animals. There are alternative system for housing and manure treatment which generate manure that are easier to handle and have less pollutants or more economic value. Treated animal waste may also be used as a feedstuff or fuel source. Most of the options of waste management result in increased costs to implement. It is necessary to assess the economics in order to find an acceptable compromise between the increased costs and the benefit to the environment. Animal welfare is also becoming more and more of an issue and it will lead to systems where animals are kept in less confined environment. The new system will have a great impact in the waste management system in the future.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.237.1-237.1
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• 2010

Recent developments such as concern over global warming, depletion of fossil fuels and increase in energy demands by the increasing world population has eventually lead to mass production of electricity using renewable sources. Ocean contains energy in form of thermal energy and mechanical energy: thermal energy from solar radiation and mechanical energy from the waves and tides. The current paper looks at generating power using waves. The primary objective of the present study is to maximize the primary energy conversion (first stage conversion) of the base model by making some design changes. The model entire consisted of a numerical wave tank and the turbine section. The turbine section had three components; front guide nozzle, augmentation channel and the rear chamber. The augmentation channel further consisted of a front nozzle, rear nozzle and an internal fluid region representing the turbine housing. Different front guide nozzle configuration and rear chamber design were studied. As mentioned, a numerical wave tank was utilized to generate waves of desired properties and later the turbine section was integrated. The waves in the numerical wave tank were generated by a piston type wave maker which was located at the wave tank inlet. The inlet which was modeled as a plate wall which moved sinusoidally with the general function, $x=asin{\omega}t$. In addition to primary energy conversion, observation of flow characteristics, pressure and the velocity in the augmentation channel, rear chamber as well as the front guide nozzle are presented in the paper. The analysis was performed using the commercial code of the ANSYS-CFX. The base model recorded water power of 29.9 W. After making the changes, the best model obtained water power of 37.1 W which represents an increase of approximately 24% in water power and primary energy conversion.

• 한국환경복원기술학회지
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• 제22권6호
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• pp.77-87
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• 2019

The first grade zones in Ecology and Nature Map are important regions for the conservation of the ecosystem, but it would be degraded by various anthropogenic factors. This study analyzes the relationship between potential land cover change and degradation of the first grade zones using land cover transition probability. As a result, it was shown that most of the first grade zones with degraded were converted from forest to urban(5.1%), cropland(27.2%), barren(11.0%) and grass(27.5%) in Gangwon and forest to urban(18.0%), cropland(15.3%), grass(28.4%), barren(12.3%) in Gyeonggi. The result of the logistic regression analysis showed that the probability of degradation of first grade zone was higher in area where was expected the higher probability of urban, cropland, barren, grass transition. The barren transition probability was the most influential and grass was the next highest. There were regional differences in the probability of urban transition and cropland transition, and the urban transition probability was more influential in Gyeonggi-do. This is because development pressure such as housing site development is high in Gyeonggi-do. Due to the limitations of the Act on Mountain Districts Management, even in the first grade zones, the grade may be degraded. Therefore, if Ecology and Nature Map are used to prevent deforestation or conversion of mountainous districts, it may contribute to the preservation of the ecosystem.

• 설비공학논문집
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• 제29권10호
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• pp.530-537
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• 2017

Scales generated inside pipes cause negative effects on heat transfer performance, pressure loss and flow rate due to increased thermal resistance and reduced flow cross-sectional area. If these scales are not prevented or eliminated, thermal-fluid performance of the facilities can be deteriorated, or in extreme cases, accidents such as explosion due to overheating can occur. There are two ways to remove the scales, physically and chemically. Removing the scales physically needs specific machines which are expensive, and removing them chemically may provoke corrosion or shorten the age of the facilities. In this study, an eco-friendly pipe scale cleaner using natural organic acid is developed by applying the concept of a limestone cave generation. The manufactured scale cleaner is applied to remove the scales in industrial, water heating and urinal pipes. The results show that this cleaner removes scales more effectively and safely compared to existing scale treatments. Scale removal efficiencies of this work is 1.2~10.7 times for industrial pipes and 1.8~15.5 times for boiler water heating pipes higher than those of conventional cleaners.