• Journal of the Korean Wood Science and Technology
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• 제44권2호
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• pp.231-240
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• 2016

The change in chemical compositions of leachate and medium density fiberboard (MDF) from a laboratory-scale simulated landfill which constructed in a plastic container containing alternating layers of soil and MDF was investigated to evaluate decomposing of MDF in soil. Four treatments were conducted: 1) MDF in soil, 2) MDF only, 3) cured UF resin in soil, and 4) soil only. Molecular weight (MW) distribution of compounds in leachate from soil only treatment did not change over time. In UF resin in soil treatment, the MW distribution shifted to a lower MW distribution over time, while the peak shifted to the left indicated changing to higher MW distribution in leachate from treatment 1 and 2 contained MDF. Higher percent nitrogen in leachate was observed in MDF containing treatments due to the UF resin in the MDF. The percent carbon slightly increased in MDF only while that greatly decreased in MDF in soil treatment maybe due to bacterial activity. The percent of extractable materials from the MDF decreased greatly on day 35 compare to day 0, and subsequently did not change much on day 77. In contrast, percent holocellulose and lignin did not change much over time. No structural change of the wood fiber in MDF occurs during the study. Water-soluble materials from MDF in soil contributed the change in chemical composition of leachate.

• 한국산학기술학회논문지
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• 제22권3호
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• pp.1-12
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• 2021

MVDC 배전기술은 현재 급격하게 도입되고 있는 태양광전원의 접속지연 문제를 해결하기 위한 효과적인 대안으로 평가되고 있지만, DC 배전망용 기기들을 개발해야 하므로 DC 배전망의 구축비용은 경제적인 측면에서의 문제점을 가지고 있다. 따라서, 본 논문에서는 태양광전원의 수용을 위한 MVDC 배전망의 도입 타당성을 평가하기 위하여, 태양광전원 단지를 용량에 따라 규모별로 정의하고, 이를 수용하기 위한 배전망을 건설하는 경우에 대하여 규모별로 수용성 모델을 제시한다. 이 모델은 배전망의 전원공급방식에 따라 AC 및 DC 배전망으로 구분되며, 수용할 태양광전원 단지의 용량에 따라 수백 MW급은 대규모, 수십 MW급은 중규모, 수 MW급은 소규모로 정의된다. 또한, 본 논문에서는 AC 및 DC 배전망의 건설비, 전력변환설비의 교체비, 운용비로 구성된 비용요소와 태양광전원의 발전수익에 따른 전력량 요금 및 REC 요금으로 구성된 편익요소를 고려하여 MVDC 배전망의 경제성평가 모델링을 제시한다. 이를 바탕으로 현재가치 환산법과 원금균등상환 방식을 이용하여 MVDC 배전망의 경제성을 평가한 결과, 태양광전원의 수용 규모에 따라 일정 연계거리 이후에서는 DC 배전망의 구축비용이 기존의 AC 배전망보다 경제적임을 알 수 있어, 본 논문에서 제시한 경제성평가 모델링의 유용성을 확인하였다.

• 한국지진공학회논문집
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• 제28권3호
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• pp.159-164
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• 2024

Recent earthquakes in Korea, like Gyeongju and Pohang, have highlighted the need for accurate seismic hazard assessment. The lack of substantial ground motion data necessitates stochastic simulation methods, traditionally used with a simplistic point-source assumption. However, as earthquake magnitude increases, the influence of finite faults grows, demanding the adoption of finite faults in simulations for accurate ground motion estimates. We analyzed variations in simulated ground motions with and without the finite fault method for earthquakes with magnitude (Mw) ranging from 5.0 to 7.0, comparing pseudo-spectral acceleration. We also studied how slip distribution and hypocenter location affect simulations for a virtual earthquake that mimics the Gyeongju earthquake with Mw 5.4. Our findings reveal that finite fault effects become significant at magnitudes above Mw 5.8, particularly at high frequencies. Notably, near the hypocenter, the virtual earthquake's ground motion significantly changes using a finite fault model, especially with heterogeneous slip distribution. Therefore, applying finite fault models is crucial for simulating ground motions of large earthquakes (Mw ≥ 5.8 magnitude). Moreover, for accurate simulations of actual earthquakes with complex rupture processes having strong localized slips, incorporating finite faults is essential even for more minor earthquakes.

• 상하수도학회지
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• 제19권4호
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• pp.480-486
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• 2005

The main goals of this work are to investigate the effect of molecular weight distribution(MWD) and activated carbon adsorption capacity after conventional coagulation and enhanced coagulation. The ozonation was very effective to decompose the NOM to smaller size and to remove molecular smaller than 1,000. The concentration of DOC was reduced 0.25mg/L and 0.56mg/L by the conventional coagulation and the enhanced coagulation, respectively The conventional coagulation was not effective to remove NOM. However, the enhanced coagulation was effective to remove MW bigger than 10,000. The higher MW was shifted to smaller weight by ozonation in the raw water and the after conventional coagulation. After enhanced coagulation the MW had not changed significantly by ozonation. Also, it was observed that the ozone dosage did not have significant impact on MW shifting to smaller size. The adsorption capacity simulated by IAST comparing K values showed that the adsorption capacity was not impacted by ozone doses. There was very strong correlation between MW smaller than 10,000 and the mid- and strongly adsorbable fractions.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.1056-1061
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• 2001

This paper describes the evaluation of noise influence of residental and boundary areas from power plant noise sources of 1200MW combined cycle power plant. Noise assessments are carried out by based on the ISO 3744, ISO 9613-1 and ISO 9613-2 to predict the noise distribution to satisfy the recommended noise level at specific locations and to calculate properly the octave noise power of main noise sources such as power transformers. air-intakes, stacks.

• 상하수도학회지
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• 제22권1호
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• pp.31-38
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• 2008

The primary objective of this study was to evaluate the variation of the molecular size distribution by granular activated carbon (GAC) adsorption. GAC adsorption was assessed by using the rapid small-scale column test (RSSCT) and high-performance size-exclusion chromatography (HPSEC) was used to analyze the molecular size distribution (MSD) in the effluent of GAC column. RSSCT study suggested that GAC adsorption exhibited excellent interrelationship between dissolved organic carbon (DOC) breakthrough and MSD as function of bed volumes passed. After GAC treatment, the nonadsorbable fraction which was about 25percents of influent DOC corresponded to the hydrophilic (HPI) natural organic carbon (NOM) of NOM fractions and was composed entirely of <300 molecular weight (MW) in the HPSEC at the initial stage of the RSSCT operation. The dominant MW fraction in the source water was 1,000~5,000daltons. At the bed volumes 2,500, MW <500 of GAC treated water was risen rather than it of source water. After the bed volumes 7,300 of operation, the MW 1,000~3,000 fraction was closed to about 80percents of DOC found in the GAC influent. The Number-average molecular weight (Mn) value determined using HPSEC for the effluent of GAC column was gently increased as DOC breakthrough progress. The quotient p(Mw/Mn) can be used to estimate the degree of polydispersity was shown greatest value for the GAC effluent at the initial stage of the RSSCT operation.

• 대한화학회지
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• 제14권1호
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• pp.29-35
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• 1970

Chacterization of MMA/AN organosol copolymer and subsequent comparison with the prior art latex copolymers has been accomplished. By means of NMR analyses, we found both types of copolymers to be random. The GPC analyses show that the organosol copolymers have a singnificantly broader MW spread than latex copolymers. This is due to the low MW stabilizer which is present as a physical mixture. As a result, the MW distribution is bimodal. Fractionation of a typical organosol copolymer yields a low MW(33,000-100,000), MMA rich fraction and a high MW (250,000-330,000), AN rich fraction. Solubility-wise, the organosol copolymers are readily soluble in the lacquer solvent MEK to give a colorless film. The prio rart copolymers, hewever, were imcompletely soluble and gave yellow, hazy film.

• Journal of Applied Biological Chemistry
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• 제43권1호
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• pp.31-36
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• 2000

Apparent MWDs of DOM in natural waters and swine wastewaters were determined through membrane ultrafiltration. The nominal MWCOs of ultrafiltration membranes by the manufacturer were confirmed to be similar with those obtained from the ultrafiltration procedures employed in this study using six MW standard compounds. Natural waters showed a wide range of MWOs, but 62.4~87.5% were in the range of MW<10K. High MW fractions were preferentially removed through water treatment processes. Swine wastewater showed two major ranges of MWDs, 49.0% in <1K and 36% in >50k while anaerobically treated swine wastewaters showed 17.5~18.0% in <1K and 53.0~58.8% in <50K. The overall DOM was reduced during anaerobic treatment by 76.8~80.0% as COD; however. the percentage of low MW fractions decreased and that of the high MW fractions increased.

• 상하수도학회지
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• 제13권2호
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• pp.66-73
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• 1999

This study was carried out to derive the removal characteristics of target materials(DOC and turbidity) during the coagulation process after the injection of coagulants(PACl and FeCl3). Used apparatus were a jar test and a pilot plant. A great portion of DOC among the total removed DOC was achieved at the slow mixing process among the coagulation process. The ranges of removed DOC and optimum pH for each coagulant were 0.45~1.47mg/l and 6.0~6.5 by PACl, and 0.97~2.61mg/l. and 5.0~5.5 by FeCl3, respectively. Both of coagulants showed little increase of DOC removal above coagulant dosage 20mg/l Molecular weight distribution(MWD) of removed DOC was measured by get filtration(GF) technique. The MWD variation by gel filtrationin(GF) for removed DOC in the coagulation process were as follows; for raw water, the percentages of each MWD for total area were < MW 6,500 25.5%, MW 6,500~66,000 67.1%, and > MW 66,000 7.4%. For the same coagulant dosage(12mg/l), the percentages of each MWD for total area by PACl were < MW 6,500 20.5%, MW 6,500~66,000 48.7%, and > MW 66,000 9.1%, and those of FeCl3 were MW 66,000 18.2%. For each coagulant, the removal percentage of MW 6,500~66,000 occurred a little, but at a part of

• 한국초전도ㆍ저온공학회논문지
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• 제6권2호
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• pp.15-19
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• 2004

As the power demand has increased and power industry deregulation has progressed, the transmission and distribution system will have more complicated problems by the influence of investment reduction and NIMBY phenomena for overall power system. It is expected that the route length per MW demand will reduce gradually from 0.6[C-km/MW] to 0.53 [C-km/MW] in 2010. This comes up to a real serious problem of system planning and operational viewpoints. HTS technologies related to power system have properties to solve these complex transmission and distribution constraints, especially for metropolitan area, in the future. As the HTS technology has developed, the HTS cable technology can be the most effective alternative to solve the future expected power network constraints. This paper describes the application methodology of developing 22.9㎸ HTS cable by CAST for practical distribution system. 22.9㎸ HTS cable under development with step-by-step application methodology can substitute the existing and planning conventional 154㎸ cable. If this scheme is applied, part of downtown 154㎸ substation of metropolitan city such as Seoul can be changed into 22.9㎸ switching station. It can give great economic, environmental and additional benefits to all of the concerned authorities.