• Macromolecular Research
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• 제12권5호
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• pp.490-492
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• 2004

We report a new method using a heating medium for the thermal decomposition of epoxy resin (EP) at temperatures ranging from 50 to 200$^{\circ}C$. EP decomposition also occurred below 50$^{\circ}C$ during a 6-day period to generate bisphenol A (BPA) at concentrations as high as 5 ppm. When polyethylene glycol was used as a heating medium, we determined the kinetics of the EP decomposition at low temperature. We determined the apparent activation energy of the overall decomposition to be 40.8 kJ/mol and the frequency factor to be 2.3${\times}$10$^3$ by monitoring the rate of BPA formation. Thus, EP is clearly unstable upon the application of heat.

• 문화기술의 융합
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• 제7권4호
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• pp.607-612
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• 2021

본 연구는 주택가격 상승 충격이 저출산에 미치는 영향과 각 변수들의 합계출산율 변동 기여도를 추정하였다. 본 연구는 기존 연구들이 시도하지 않았던 샤플리 분해와 패널 VAR의 예측오차분산분해를 통해 과거 출산율 하락 경험치에 대한 각 변수들의 기여도와 각 변수의 향후 기여도를 추정하여 차별성이 있다. 본 연구의 주요 분석결과는 다음과 같다. 우리나라 합계출산율의 하락은 최근 합계출산율 하락 흐름에 강한 영향을 받았으며, 이 영향력은 향후 미래에도 지속될 것으로 전망되었다. 주거비의 경우는 과거 주택 매매가격은 전세가격에 비해 상대적으로 합계출산율변동에 미친 기여도가 작았으나, 향후 미래에는 장기적으로 그 영향력이 커질 것으로 전망되었다. 주택 매매가격, 전세가격 이외 사교육비 역시 합계출산율 하락에 주요 원인으로 작동하였음을 실증하였고, 높은 사교육비 부담이 장기적으로도 합계출산율을 낮출 것으로 전망되었다.

• 한국분무공학회지
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• 제25권3호
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• pp.132-138
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• 2020

N₂O is hazardous atmosphere pollution matter which can damage the ozone layer and cause green house effect. There are many other nitrogen oxide emission control but N₂O has no its particular method. Preventing further environmental pollution and global warming, it is essential to control N₂O emission from industrial machines. In this study, the thermal decomposition experiment of N₂O gas mixture is conducted by using cylindrical reactor to figure out N₂O reduction and NO formation. And CHEMKIN calculation is conducted to figure out reaction rate and mechanism. Residence time of the N₂O gas in the reactor is set as experimental variable to imitate real SNCR system. As a result, most of the nitrogen components are converted into N2. Reaction rate of the N₂O gas decreases with N₂O emitted concentration. At 800℃ and 900℃, N₂O reduction variance and NO concentration are increased with residence time and temperature. However, at 1000℃, N₂O reduction variance and NO concentration are deceased in 40s due to forward reaction rate diminished and reverse reaction rate appeared.

• 대한화학회지
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• 제37권2호
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• pp.199-205
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• 1993

구리-아민류착물에 의한 과산화수소의 초기분해속도를 pH7.3~11.8 범위에서 측정하였다. 과산화수소의 분해속도는 pH에 따라 증가하였다가 감소하였다. 이들 실험결과에 일치하는 가능한 메카니즘이 제안되었다. 이 메카니즘은 과산화수소와 구리-아민류착물의 탈양성첨가를 거친 다음에 속도 결정단계에서 퍼옥소구리착물이 생성되는 반응과정과 일치한다.

• Journal of Ecology and Environment
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• 제35권2호
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• pp.99-109
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• 2012

Litterfall dynamics in forests are assessed by estimating biomass production and decomposition. However, there have been few studies on how litter dynamics impact the health and management of ecosystems. Here, a new approach to measure and assess ecosystem function is presented based on conventional methods using littertraps, litterbags, and the mass on the forest floor. To assess the status of litter dynamics, the decay rate (k) was estimated from a litterbag experiment, and removal rates ($k_i$) were determined from mass balance on the forest floor at 21 sites on three mountains in South Korea. The $k_3$ (organic mass ratio of $O_i$ and $O_e+O_a$ + A horizons in November) values in an equilibrium state in South Korea were within the range of $k{\pm}0.174$ when considering the annual variation of litterfall production. This study also suggests that sampling sites for these types of studies should be in the middle, not at the ends, of steady slopes on the forest floor.

• 신재생에너지
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• 제17권2호
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• pp.40-49
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• 2021

This paper explains the development process of methane decomposition to hydrogen and carbon black using solar thermal energy. It also demonstrates the advantages and disadvantages of five different reactors for each development stage, including the reactor's experimental results. Starting with the initial direct heating type reactor, the indirect heating type reactor was developed through five modifications. The 40-kWth solar furnace installed at the Korea Institute of Energy Research was used for the experiment. In the experiment using the developed indirect heating reactor, an 89.0% methane to hydrogen conversion rate was achieved at a methane flow rate of 40 L/min, obtained at about twice the flow rate compared to previous advanced studies.

• 한국토양비료학회지
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• 제33권4호
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• pp.302-309
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• 2000

미생물제의 퇴비부숙효과를 검토하기 위하여 국내에 유통되고있는 Lacto외 4종 미생물제에 대한 퇴비부숙 촉진 효과를 보면 볏짚에서는 락토 및 천보, 생력등 일부 미생물(微生物)제의 처리에 의하여 초기에 부숙촉진경향이 관찰되었으나 초기에 부숙이 촉진되었던 처리는 후기에 부숙속도가 늦어지고 초기에 부숙속도가 늦었던 처리는 후기에 부숙속도가 빨라짐으로서 결국 미생물제처리 40일경에는 미생물제 사이에 뚜렷한 차이가 인정되지 않았다. 또한 미생물제를 시용하면 볏짚부숙중에 사상균수의 증가가 현저하였으며 볏짚의 부숙과 사상균수의 변동과 일치하는 경향을 보였으나, 계분톱밥부숙에 미치는 미생물제의 영향을 보면 퇴적초기에는 세균, 방선균, 사상균 모두 균수가 극히 적었으며 세균수만이 시간이 경과함에 따라 균수의 증가가 현저한 점으로 미루어 볼 때 세균이 계분톱밥퇴비의 부숙에 밀접한 관련이 있는 것으로 판단되었다.

• The Korean Journal of Ecology
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• 제8권3호
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• pp.163-169
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• 1985

The composition rates of litters were studied at Camellia japonica forests in Koje-Do and Haenam, and at Quercus acuta, Quercus acutissima, Cryptomeria japonica, and Chamaecyparis abtusa forests in Haenam. Total amounts of nitrogen, phosphorus, potassium, calcium, and sodium in litter samples were measured and the relation between these amounts and decomposition rate was studied. Annual litter production were rarely different at each forest in Haenam. The amount of accumulated organic matter was about 4 times greater at C. japonica forest in Koje-Do than at the C. japonica forest in Haenam. These amounts were 5, 282.1 $\pm$ 1, 026.03g/m2 in Koje-Do and 1, 420.7 $\pm$ 384.77g/$m^2$ in haenam. The decomposition rate were rarely differnet at each forest in Haenam, but the rates showed great difference at C. japonica foreests in Koje-Do and Haenam. The rates were 0.093 and 0.313 at C. japonica forests in Koje-Do and in Haenam respectively. The sodium contents were 0.472% and 0.229% on L layer and on Css layer of C. japonica forest in Koje-Do, while they were 0.034% and 0.043% on L layer, and on Css layer of C. jpaonica forest in Haenam. It is sugested that much difference in the salt contents in the forest floor was present from the results of sodium content measured at each site, and that the decomposition rate was affected by the much concentration of salt in Koje-Do.

• 한국음향학회지
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• 제21권3호
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• pp.315-322
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• 2002

본 논문에서는 음성 신호 시간축 분할의 새로운 기법으로, 비트율과 왜곡을 함께 고려한 기법이 제안되었다. 시간축 분할에 필요한 보간 함수는 학습 음성 데이터로부터 얻어진다. 보간 함수는 두 타겟간의 길이에 따라 유일하게 결정되므로 보간 함수는 추가 정보없이 표현된다. 타겟 샘플은 비트율을 최소화시키면서 동시에 최대 스펙트럼 오차가 문턱 치보다 작게 되도록 선택하였다. 제안된 기법은 음성 부호화기의 스펙트럼 변수로 널리 사용되는 LSP계수의 부호화에 적용되었으며, 모의실험 결과 평균적으로 8 bits/Frame의 비트율에서 1.4 dB의 스펙트럼 왜곡이 얻어짐을 알 수 있었다.

• The Korean Journal of Ecology
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• 제24권2호
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• pp.81-85
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• 2001

Decomposition of Zizania latifolia was investigated with litterbag method for 13 months from November in 1998 to December in 1999, at the fringe of stream at Boryeong, Chungnam Province in Korea. After 13 months, remaining mass of leaves, culms and rhizomes was 16.9, 14.7, and 10.1%, respectively. Mass loss of the rhizomes was higher than those of the leaves and culms. The decay rate of leaves, culms and rhizomes was 1.86, 2.00 and 2.36 per year, respectively. Initial concentration of N, P, K, Ca, and Mg of leaves, culms and rhizomes was 18.0, 14.5, 44.0 mg/g for N,0.18, 0.12, 0.67 mg/g for P, 14.1 ,14.2, 14.8 mg/g for K,3.6, 1.5, 0.3 mg/g for Ca, 1.1, 0.5, 0.5 mg/g for Mg, respectively. Concentrations of N and P in rhizomes were higher than those in leaves and culms. Except for Mg in rhizomes, there was no immobilization period during the decomposition. Most of the N, P and Mg were lost during the first 3 months. In case of K and Ca, most were lost within 1 month.