• 전자공학회논문지D
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• 제34D권9호
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• pp.72-79
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• 1997

The dominant physical process repsonsible for the nonlinear gain is from spectral-hole burning with the time constant fo about 50fs and the contribution to the nonlinea rgain form hot carriers effect is determined to be about 15% of the contribution due to spectral-hole burning. To prove the above results we fit the data of hall and found that hot carriers have a profound effect on their experimental data despite the fact that the magnitude of hot carriers effect is only 15% of spectral-hole burning. We suggest that the experimenta with a pump pulse width of 180 fs is very sensitive in detecting the effect of hot carriers, but is not sensitive in detecting much faster process associated with spectral-hole burning.

• 임산에너지
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• 제22권1호
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• pp.24-29
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• 2003

낙엽송 간벌재 톱밥보드로 우드세라믹을 제조한 후 수지함침율 및 소성온도에 따른 우드세라믹의 표면온도 변화를 조사하였다. 히터의 표면온도가 증가함에 따라 우드세라믹의 표면온도도 급속히 증가하였으며 수지함침율 70∼80%, 소성온도 800∼1000℃ 조건으로 제조된 우드세라믹의 표면 온도가 상대적으로 높았다. 히터의 표면온도보다 우드세라믹 표면온도의 하강속도가 느려 우드세라믹이 오랜 시간 열을 유지하고 있음을 알 수 있었다.

• 한국안전학회지
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• 제8권1호
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• pp.35-46
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• 1993

This paper was concerned with the risk assessment about oxidizing substances as dangerous goods by burning test method. The sample. which was formed with the heaped cone-shape. was composed of solid oxidant and sawdust. The burning time of each sample was measured under the following various conditions circumstance temperature. mixing ratio of oxidizing substance and sawdust. particle size of sawdust and kinds of sawdust. As a results. the effective combustibility was gained when the sawdust content was 20∼30 wt.% in the sample and the lauan with -30+50 mesh was used. But. although the circumstance temperature increased. burning efficiency of the samples wet$.$e not affect by it. Finally. the average burning times were obtained by considering the weighting factors related on the mixing ratio and the circumstance temperature. And then. it were compared with the combustion risk level and the effects of cation and anion of oxidizing substances as dangerous goods.

• 한국안전학회지
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• 제11권3호
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• pp.137-142
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• 1996

Combustion characteristics of immobilized methyl, ethyl and propyl alcohols on sands were studied. Experiments were performed by burning methyl, ethyl and propyl alcohols Immobilized on sands (particle size 0.1~5mm) and ceramic balls(particle size 5mm) to measure mass burning rate, height burning rate and combustion temperature. It was concluded that the longer time from ignition to extinguishment was resulted from the larger particle size of sands and the smaller size of sands exhibited the higher mass burning rate. Of alcohols tested the relative magnitude of facilitation of combustion was methyl>ethyl>propyl alcohol. Combustion temperature of alcohols, without regard to the types of alcohols, was not increased with smaller sands. However, with larger sands, combustion temperatare of alcohols was increased with the larger particle.

• 한국세라믹학회지
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• 제44권9호
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• pp.517-523
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• 2007

For the preparation of tricalciumaluminate $(C_3A)$ clinker, in traditional clinkering method using oxides and carbonates as a raw material, uneconomical repetition of burning have been necessary to avoid the melting of clinker by eutectic reaction in the system $CaO-Al_2O_3$. In this study, special starting raw materials for the clinker burning were prepared from a mixture of oyster shell and aluminium hydroxide by heating to $1100^{\circ}C$ and hydrating at $30^{\circ}C$. The starting raw materials, hardened body with weak hydraulic strength, were mainly composed of $C_3AH_6$ formed by resolution-precipitation mechanism of the system $CaO-Al_2O_3-H_2O$. By heating them, relatively pure $C_3A$ clinker could be obtained by one-time burning at the fairly lower temperature than that of conventional method. The easier formation of $C_3A$ clinker seemed to be caused by higher compositional homogeneity and stoichiometry of the starting materials, high surface area and crystallographic instability of the thermally decomposed products, and the catalytic effect of decomposed moisture on the early-stage crystallization of calciumaluminates. The basic hydration behavior of the clinker was also confirmed.

• Journal of the Korean Wood Science and Technology
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• 제31권1호
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• pp.41-45
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• 2003

MDF를 재료로 600, 800, 1,000, 1,200℃에서 소성 하여 우드세라믹을 제조한 후 소성 전 수지 함침율과 소성온도에 따른 우드세라믹의 표면온도를 조사하였다. 함침율, 소성온도 및 시간의 경과에 따라 표면온도가 증가하였으며, 1,200℃ 시료의 온도가 가장 높게 나타났다. 시간의 경과에 따른 표면온도의 하강은 800℃ 시료의 온도가 가장 빨리 감소하였다.

• 한국자동차공학회논문집
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• 제3권5호
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• pp.122-134
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• 1995

The present study was investigated combustion characteristics of methane-air mixtures at stratified charge in a constant volume combustion chamber. The main results obtained from this study can be summarized as follows. In case of ${\phi}_s=1.0$, total burning times greatly affected rather than initial time of pressure increase and maximum combustion pressure. In case of ${\phi}_t=1.0$, initial time of pressure increase and total burning times were affected considerably in comparison with the case of ${\phi}_s=1.0$. Also, even the very lean mixture which total equivalence ratio is ${\phi}_t=0.69$(${\phi}_s=1.0$, ${\phi}_m=0.65$), by changing configuration of the critical passage-hole and using a stratified mixture, it is possible to decrease substantially the initial time of pressure increase. total burning times and NOx concentration without deteriorating combustion characteristics such as maximum combustion pressure, rate of heat release etc. in comparison with the use of single chamber(in case of ${\phi}=1.0$) only. Specifically, our trends were revealed remarkably in the case of Type D which is reduced a flame contact area of sub-chamber side of the passage-hole.

• 한국수산과학회지
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• 제8권3호
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• pp.150-156
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• 1975

Diesel 기관의 연소는 매우 복잡한 현상이다. 이 복잡한 연소과정을 각운전조건하에서 구한 열발생율에 의해 해석했으며 그 결과 다음 사항이 밝혀졌다. 1. Diesel기관의 연소기간은 예혼합기연소기관과 황산연소기관으로 나누어 생각할 수 있다. 2. 예혼합기연소부분이 클수록 효율은 양호하나 최고압력이 높아져 정숙한 운전이 되지 못하고 확산연소기간이 길수록 운전은 정숙하나 효율은 떨어지고 배기온도는 상승한다. 3. 예혼합기 연소부분은 주로 발화지연에 지배되나 확산연소기간은 산소의 확산에 지배된다. 4. 실험범위내에서 기관의 효율은 분사량과 회전수가 일정하면 분사시기가 빠를수록 효율은 증가했으나 압력의 상승은 효율의 증가보다 높았다.

• 한국제4기학회지
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• 제16권2호
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• pp.1-8
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• 2002

본 연구에서는 1995-2001년에 고성지방의 산불 다발생지 10개 지역을 대상으로, 산불발생의 인위적 요인과 기상요인을 파악하였다. 그 결과를 요약하면 다음과 같다. 같은 곳에서 산불이 3회 이상 발생한 곳은 거진읍 거진리, 간성읍 선유실리, 죽왕면 마좌리 등이고, 인접지역에서 계속, 산불이 3회 이상 발생한 곳은 토성면의 학야리, 성대리, 인흥리 등이다. 1995-2001년에 산불발생 퐁 46회 중, 3월 11회, 4일 11회, 11월 7회, 1월 6회, 2일 6회, 12일 3회, 10일 2회 등이고, 산불발생이 많은 시간은 11-18시이다. 산불 발생원인은 군사훈련, 논.밭두렁소각, 쓰레기소각, 농산물폐기물 소각, 성묘객실화, 담뱃불, 방화 등인데, 군사훈련과 군부대내의 쓰레기 소각으로 인한 산불발생이 제일 많았다. 산불이 제일 많은 3,4월, 산불 발생 22일의 일평균 최고기온은 일평년값보다 $5^{\circ}C$높았고, 일평균상대습도는 23% 낮았으며, 일평균풍속은 0.8m/s강했다. 그리고 3,4월에는 퓐의 특성을 가진 강풍이 자주 나타난다. 이때, 한반도 중심의 기압배치는 $\ulcorner$남고북저$\lrcorner$형이다.

• Journal of the Korean Wood Science and Technology
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• 제15권3호
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• pp.56-67
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• 1987

Plywoods used for construction as a decorative interior material are inflammable and can make fire accidents, causing destruction of human life and property. Therefore, it is indeed required to make fire-retardant treated plywood. In this study, 3.7mm yellow meranti plywoods were soaked in 18% boric acid solutions and tap water by hot-cold bath for 1/2, 2/2, 4/2, 6/2 hours and redrying of treated plywoods was carried out by press drying at the platen temperature of 110, 130, 160, $180^{\circ}C$ and then it was conducted to investigate solution absorption, drying rates, dynamic young's modulus. specific gravity and fire-retardant factors such as burning point, flame spread length. flame exhausted time, back side carbonized area and weight loss by treating time, treating solutions and platen temperature. The results are as follows; 1. When plywood was impregnated with the hot bath temperature of $70^{\circ}C$ for 1. 2, 4, 6 hours and the cold bath temperature of $15^{\circ}C$ for 2 hours respectively, retentions of boric acid were 1.565, l.597, 1.643, 1.709kg/$(30cm)^3$ and all of them exceeded the minimum retention [1.125kg/$(30cm)^3$] even in the shortest treatment. 2. In hot-cold bath method for 1/2 hours, the drying rates of treated plywood remarkably increased with the extension of platen temperature of 110, 130, 160, $180^{\circ}C$ and the values of boric acid treated plywood were 5.900, 10.196, 45.42, 54.958m.c%/min and the values of water treated plywood were 6.014, 12.373, 46.520, 55.730m.c%/min and drying rates of water treated plywood were faster than those of boric acid treated plywood. 3. The values of boric acid treated plywoods in dynamic young's modulus were widely higher than those of water treated plywoods. And it can be observed that there were highly significant differences for treating time between dynamic young's modulus, and the values of boric acid plywoods increased with the extension of treating time but on the contrary water treated plywoods were decreased values with prolonged time 4. It was observed that there were highly significant differences for platen temperature between dynamic young's modulus. When the values of water treated plywoods in dyna nic young's modulus were abruptly decreased according to the rise of platen temperature. boric acid treated plywoods showed rather increased values at $160^{\circ}C$ of platen temperature. And in 2- way interactions, there were also highly significant for dynamic young's modulus between treating time x treating solutions and platen temperature x treating solutions. 5. Correlation coefficients of fire-retardant factors were shown in table 5. It could be recognized that there were close correlations between the treating solutions and burning point, flame spread length, back side carbonized area, flame exhausted time and weight loss, but there was no correlation between fire-retardant factors and treating time and platen temperature. 6. From table 6, it can be observed that there were highly significant differences for burning point, flame spread length, flame exhausted time, back side carbonized area, weight loss between treating solutions. And in 2-way interactions, there were highly significant for burning point, flame spread length, weight loss between treating time $\times$ treating solutions.