• 한국경영과학회지
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• 제19권3호
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• pp.235-241
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• 1994

We consider a B/G/1 queueing with vacations, where the server closes the gate when it begins a vacation. In this system, customers arrive according to a Bernoulli process. The service time and the vacation time follow discrete distributions. We obtain the distribution of the number of customers at a random point in time, and in turn, the distribution of the residence time (queueing time + service time) for a customer. It is observed that solutions for our discret time B/G/1 gated vacation model are analogous to those for the continuous time M/G/1 gated vacation model.

• 대한수학회보
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• 제33권2호
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• pp.205-211
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• 1996

Throughout this paper, we will work in the category of compact connected manifolds and continuous maps. If $X_1, X_2$ are manifolds, $f, g: X_1 \to X_2$ are maps, then a point $x \in X_1$ is a coincidence of f and g iff f(x) = g(x) ; the set of all such points is denoted by Coin(f,g).

• 한국재료학회:학술대회논문집
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• 한국재료학회 1992년도 추계학술발표강연 및 논문개요집
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• pp.9-9
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• 1992

• 대한수학회보
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• 제46권2호
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• pp.347-358
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• 2009

In [8], the author decomposed the Dirichlet form associated to a bounded generator G of a $weakly^*$-continuous, completely positive, KMS-symmetric Markovian semigroup on a von Neumann algebra M. The aim of this paper is to extend G to the unbounded generator using the bimodule structure and derivations.

• 대한수학회논문집
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• 제10권2호
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• pp.393-400
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• 1995

We define a group extension and characterized some properties of the group extension. In particular, we show that the quotient map $\nu$ is a continuous group isomorphism and subgroup $H_1(H_2)$ is normal in $G_1(G_2)$.

• 유기물자원화
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• 제23권1호
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• pp.45-51
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• 2015

본 연구에서는 비귀금속 촉매인 iron(II) phthalocyanine (FePc)와 cobalt tetramethoxyphenylporphyrin(CoTMPP)를 환원전극촉매로 이용하여 미생물연료전지의 연속운전을 진행하였다. 연속운전은 유기물 부하 (0.5~3 g COD/L/d)와 HRT (0.25~1 day)의 조건을 달리 운전하여 미생물연료전지의 성능을 평가하였다. 미생물연료전지의 전력밀도는 환원전극의 성능에 크게 영향을 받았으며, 최대전력밀도는 $3.3W/m^3$로 백금을 사용한 미생물연료전지에서 나타났다. 하지만, HRT의 조건을 달리 한 실험에서 FePc를 사용한 미생물연료전지가 백금을 사용한 미생물연료전지와 유사한 성능을 나타냈으며, 연속운전에서 백금 촉매를 대체할 수 있는 적합한 물질로 나타났다. 반면에 CoTMPP를 사용한 미생물연료전지는 연속운전에서 내부 저항의 급격한 증가로 전력밀도가 급격히 감소하였다.

• Mycobiology
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• 제42권3호
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• pp.249-255
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• 2014

We evaluated a more practical and cost-effective immobilization carriers for ethanol production using the yeast Saccharomyces cerevisiae. Three candidate materials-rice hull, rice straw, and sawdust-were tested for their cell-adsorption capacity and operational durability. Derivatizations of rice hull, rice straw, and sawdust with the optimal concentration of 0.5 M of 2-(diethylamino)ethyl chloride hydrochloride (DEAE HCl) resulted in > 95% adsorption of the initial yeast cells at 2 hr for DEAE-rice hull and DEAE-sawdust and in only approximately 80% adsorption for DEAE-rice straw. In addition, DEAE-sawdust was found to be a more practical carrier for immobilizing yeast cells in terms of operational durability in shaking flask cultures with two different speeds of 60 and 150 rpm. Furthermore, the biosorption isotherms of DEAE-rice hull, -rice straw, and -sawdust for yeast cells revealed that the $Q_{max}$ of DEAE-sawdust (82.6 mg/g) was greater than that of DEAE-rice hull and DEAE-rice straw. During the 404-hr of continuous column reactor operation using yeast cells immobilized on DEAE-sawdust, no serious detachment of the yeast cells from the DEAE-sawdust was recorded. Ethanol yield of approximately 3.04 g/L was produced steadily, and glucose was completely converted to ethanol at a yield of 0.375 g-ethanol/g-glucose (73.4% of the theoretical value). Thus, sawdust is a promising practical immobilization carrier for ethanol production, with significance in the production of bioethanol as a biofuel.

• 대한환경공학회지
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• 제39권9호
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• pp.505-512
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• 2017

NaA 제올라이트 분말(Z-PA) 및 펠렛(Z-BA)를 이용하여 수중의 Sr 이온의 흡착특성을 검토하였다. 회분식 실험에서 Z-BA와 Z-PA에 의한 Sr 이온의 흡착은 유사 1차식보다는 유사 2차식에 잘 부합되었고, 등온 흡착실험 결과는 Langmuir 등온식에 잘 부합하였으며, 이 등온식으로부터 구한 최대 흡착량은 Z-PA는 233.32 mg/g, Z-BA는 164.60 mg/g이었다. 연속식 실험에서 Sr 이온의 농도가 증가함에 따라 Sr 이온의 총 흡착량(q)는 증가하였으나 파과시간, 처리 부피($V_{eff}$) 및 총 제거율(R)은 감소하였다. 실험으로부터 구한 파과곡선은 Thomas 모델식에 의해 잘 모사되었다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.60-60
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• 2017

It is important to measure the gas exchange activity of the crops in canopy scale to understand the process of biomass production and yield formation. Thermal imaging of the canopy surface temperature is a powerful tool to detect the gas exchange activity of the crop canopy. The simultaneous measurement of the canopy temperature and the meteorological data enables us to calculate the canopy diffusive conductance ($g_c$) based on the heat flux model (Monteith et al. 1973, Horie et al. 2006). It is, however, difficult to realize the long-term and continuous monitoring of $g_c$ due to the occurrence of the calculation error caused by the fluctuation of the environmental condition. This is partly because the model assumption is too simple to describe the meteorological and aerodynamic conditions of the crop canopy in the field condition. Here we report the novel method of the direct measurement of the aerodynamic resistance ($r_a$) of the crop canopy, which enables us the stable and continuous measurement of the gas exchange capacity of the crop plants. The modified heat balance model shows the improved performance to quantify $g_c$ under the fluctuating meteorological condition in the field. The relationship between $g_c$ and biomass production of rice and soybean varieties is also discussed in the presentation.

• 한국연초학회지
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• 제31권1호
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• pp.39-44
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• 2009

Hydrogen cyanide (HCN) is present in both the particulate and vapor phase of cigarette mainstream smoke. It is one of the 44 harmful substances on Hoffmann's list and is known to be a major ciliatoxic agent in cigarette mainstream smoke. Typically the determination of HCN in cigarette mainstream smoke has been done through colorimetric and electrochemical techniques, such as UV-spectrophotometry (UV), continuous flow analyzer (CFA), ion chromatography (IC) and capillary GC-ECD. In particular, CFA commonly has been using analysis hydrogen cyanide in cigarette smoke and the basic principle is pyridine-pyrazolone reaction. In this study, the more optimized analytical method is suggested isonicotinic acid-pyrazolone reaction method than previous pyridine-pyrazolone reaction method, a commonly used method for the determination of cyanide in water and air, by CFA. Sample collection was optimized by trapping particulate and vapor phase of smoke separately. The optimum NaOH concentration of the trapping solution was shown to be 0.2 M. HCN was stable up to 6 hours in this concentration but only 3 hours in 0.1 M solution. The sensitivity of this method was fairly good and it might be used in analysis of HCN in cigarette mainstream smoke.