• 한국경영과학회:학술대회논문집
• /
• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
• /
• pp.841-844
• /
• 2002

Recently there has been an increasing interest in queueing models with disasters. Upon arrival of a disaster, all the customers present are noshed out. Queueing models with disasters have been applied to the problems of failure recovery in many computer networks systems, database systems and telecommunication networks in this paper, we suffest the steady state and sojourn time distributions of the M/G/l model with disaster and mass alway when the system is empty.

• 한국수산과학회지
• /
• 제32권4호
• /
• pp.399-403
• /
• 1999

우리나라 인근 해역에서 가장 쉽게 채취할 수 있는 해조류 중의 하나인 S. sagamianum을 이용한 Pb 및 Cr의 생체흡착 실험을 수행하였다. Pb 및 Cr은 15분 안에 흡착 평형에 도달하였으며, 평형흡착량은 각각 224.5mg Pb/g biomass 및 77.5mg Cr/g bio-mass로서 Pb의 흡착량이 Cr보다 약 3배정도 높았다. 또한 pH가 감소할수록 Pb 및 Cr의 홉착량은 감소하였으나 Pb가 상대적으로 많은 영향을 받는 것으로 나타났다. Pb, Cr, Cu 및 Cd 혼합용액에서는 Pb>Cu>Cr>Cd 순으로 흡착하였으며, Pb 및 Cr 이온이동량 존재하는 용액에서의 흡착은 거의 1 : 1로 흡착이 이루어졌다. Pb 및 Cr흡착 후에 0.1 M HCl, 0.1 M $HNO_3$ 및 0.1 M EDTA으로 탈착 실험을 수행하니, Pb는 의 경우에는 $95\%$이상 탈착되었으나 Cr의 경우 S. sagamianum와의 결합력이 상대적으로 강하여 탈착율이 $51\%$이하로 낮았다.

• Journal of Information Processing Systems
• /
• 제7권4호
• /
• pp.679-690
• /
• 2011

In this paper we consider a local area network (LAN) of dual mode service where one is a token bus and the other is a carrier sense multiple access with a collision detection (CSMA/CD) bus. The objective of the paper is to find the overall cell/packet dropping probability of a dual mode LAN for finite length queue M/G/1(m) traffic. Here, the offered traffic of the LAN is taken to be the equivalent carried traffic of a one-millisecond delay. The concept of a tabular solution for two-dimensional Poisson's traffic of circuit switching is adapted here to find the cell dropping probability of the dual mode packet service. Although the work is done for the traffic of similar bandwidth, it can be extended for the case of a dissimilar bandwidth of a circuit switched network.

• Journal of the Korean Statistical Society
• /
• 제30권4호
• /
• pp.661-666
• /
• 2001

In this paper we consider an M/G/1 queue where the server of the system has a vacation time and the service policy is limited-1. In this system, upon termination of a vacation the server returns to the queue and serves at most one message in the queue before taking another vacation. We consider two models. In the first, if the sever finds the queue empty at the end of a cacation, then the sever immediately takes another vacation. In the second model, if no message have arrived during a vacation, the sever waits for the first arrival to serve. The analysis of this system is particularly useful for a priority class polling system. We derive Laplace-Stieltjes transforms of the waiting time for both models, and compare their mean waiting times.

• 한국식품영양학회지
• /
• 제25권4호
• /
• pp.713-718
• /
• 2012

향나무 에탄올 추출물에 대한 암 전이 억제 효과를 측정하기 위하여 세포 수준에서 암 전이에 밀접히 관련되어 있는 galectin-3에 대한 억제 효과를 colon 26-M3.1 lung carcinoma에서 측정하였다. 향나무 추출물 $5{\mu}g/m{\ell}$, $50{\mu}g/m{\ell}$ 및 $500{\mu}g/m{\ell}$ 처리 시, 농도 의존적으로 galectin-3에 대한 저해 효과를 나타내었다. 한편, 암 전이 관련 있는 또 다른 단백질로 MMP 효소에 대한 직접적인 억제효과를 측정한 결과, 향나무 추출물 $5{\mu}g/m{\ell}$, $50{\mu}g/m{\ell}$ 및 $500{\mu}g/m{\ell}$ 처리 시 직접적으로 MMP-1, MMP-2 및 MMP-9 효소에 대해서 농도의존적인 저해 효과는 나타났으나, 강한 활성으로 평가되지는 못하였다. Colon 26-M3.1 lung carcinoma을 이용한 in vivo mouse 모델에서 향나무 추출은 농도 의존적으로 전이 억제 효과를 나타내었고, MMP-2 활성화 물질인 relaxin과 병용투여 시, relaxin의 기능에 영향을 받지 않는 것으로 나타났다. 따라서 in vivo mouse 모델에서 나타난 암 전이 억제 효과는 galectin-3 저해로 인한 효과로 사료된다.

• 한국물환경학회지
• /
• 제27권4호
• /
• pp.516-522
• /
• 2011

This study was performed to investigate the removal characteristics of phosphate by adsorption on olivine, which is generated as industrial by-products from quarry. The adsorption of phosphate on olivine was significantly achieved within 1 hour and equilibrated after 3 hours. The adsorption capacity of phosphate was enhanced with decreasing pH. The maximum adsorption capacity was observed to be 0.463 mg/g in the condition of pH 3. The $Ca^{2+}$ and $Mg^{2+}$ ion amount per adsorbent eluted from olivine was increased with decreasing pH. The precipitation test showed that phosphate in aqueous phase under the condition of pH 3 ~ 9 could be eliminated largely by adsorption on olivine, not precipitation. Freundlich adsorption model were successfully applied to describe the adsorption behavior of phosphate on olivine. The $q_m$ of Langmuir adsorption model were 1.3369 mg/g, 1.0544 mg/g, 1.0288 mg/g at pH 3, 6 and 9, respectively. The $K_F$ of Freundlich adsorption model were 0.4247 mg/g, 0.3399 mg/g, 0.2942 mg/g at pH 3, 6 and 9, respectively. The olivine showed high feasibility as a adsorbent for the removal of $PO_4$-P.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제11권1호
• /
• pp.72-79
• /
• 2006

Kojic acid production by Aspergillus flavus strain S44-1 using sucrose as a carbon source was carried out in a 250-mL shake flask and a 2-L stirred tank fermenter. For comparison, production of kojic acid using glucose, fructose and its mixture was also carried out. Kojic acid production in shake flask fermentation was 25.8 g/L using glucose as the sole carbon source, 23.6 g/L with sucrose, and 6.4 g/L from fructose. Reduced kojic acid production (13.5 g/L) was observed when a combination of glucose and fructose was used as a carbon source. The highest production of kojic acid (40.2 g/L) was obtained from 150 g/L sucrose in a 2 L fermenter, while the lowest kojic acid production (10.3 g/L) was seen in fermentation using fructose as the sole carbon source. The experimental data from batch fermentation and resuspended cell system was analysed in order to form the basis for a kinetic model of the process. An unstructured model based on logistic and Luedeking-Piret equations was found suitable to describe the growth, substrate consumption, and efficiency of kojic acid production by A. flavus in batch fermentation using sucrose. From this model, it was found that kojic acid production by A. flavus was not a growth-associated process. Fermentation without pH control (from an initial culture pH of 3.0) showed higher kojic acid production than single-phase pH-controlled fermentation (pH 2.5, 2.75, and 3.0).

• 수산해양교육연구
• /
• 제26권2호
• /
• pp.316-321
• /
• 2014

The pharmacokinetics of erythromycin (EM) after oral administration was studied in the cultured olive flounder, Paralichthys olivaceus, using LC/MS/MS. After single- or multiple-dose administration of EM (50, 100, 200 mg/kg body weight and 50 mg/kg for 5 days) by oral route in olive flounder ($350{\pm}40g$, $22{\pm}0.5^{\circ}C$), the concentration in the serum was determined at 1, 3, 6, 9, 24, 72, 120, 168, 264, 360, 504 and 720 h post-dose. The kinetic profile of absorption, distribution and elimination of EM in serum were analyzed fitting to a two-compartment model by WinNonlin program. The area under the concentration-time curve (AUC), maximum concentration ($C_{max}$), time for maximum concentration ($T_{max}$) following oral administration of 50, 100 and 200 mg/kg b.w. and 50 mg for 5 days. EM was $165.3hr^*{\mu}g/m{\ell}$ ($C_{max}$, $34.63{\mu}g/m{\ell}$; $T_{max}$, 1.56 hr), $212.8hr^*{\mu}g/m{\ell}$ ($C_{max}$, $60.38{\mu}g/m{\ell}$; $T_{max}$, 3.99 hr), and $592.37hr^*{\mu}g/m{\ell}$ ($C_{max}$, $63.01{\mu}g/m{\ell}$; $T_{max}$, 4 hr), respectively. The results of this study related to dosage and ${\mu}{\cdot}$withdrawal times could be used for prescription of EM in field for the treatment of bacterial diseases in olive flounder.

• 한국식품영양과학회지
• /
• 제30권3호
• /
• pp.500-504
• /
• 2001

Gamma irradiation was applied to reduce egg allergy. Ovalbumin (OVA), an egg white protein, was used as model allergen and was gamma-irradiated at 3, 5, or 10 kGy in an aqueous state (2.0 mg/mL). The changes in allergenic and antigenic properties of OVA resulted from gamma irradiation were monitored by ELISA with serum from egg-hypersensitive patients (H-IgE), and mouse monoclonal IgG (M-IgG) or rabbit polyclonal IgG (R-IgG). The binding ability of H-IgE to irradiated OVA was dose-dependently reduced. However, IgGs from animal did better recognize 3 or 5 kGy-irradiated OVA. In the evaluation of immune reactivity using blind test, the reactivity of H-IgE rapidly decreased depending upon the irradiation dose. However, the reactivities of M-IgG and R-IgG was higher at 5 and 3 kGy-irradiated OVA than non-irradiated control. The results provide a new possibility to use irradiation process for reducing the allergenicity of egg white.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제6권2호
• /
• pp.683-701
• /
• 2012

IEEE 802.11 standard has achieved huge success in the past decade and is still under development to provide higher physical data rate and better quality of service (QoS). An important problem for the development and optimization of IEEE 802.11 networks is the modeling of the MAC layer channel access protocol. Although there are already many theoretic analysis for the 802.11 MAC protocol in the literature, most of the models focus on the saturated traffic and assume infinite buffer at the MAC layer. In this paper we develop a unified analytical model for IEEE 802.11 MAC protocol in ad hoc networks. The impacts of channel access parameters, traffic rate and buffer size at the MAC layer are modeled with the assistance of a generalized Markov chain and an M/G/1/K queue model. The performance of throughput, packet delivery delay and dropping probability can be achieved. Extensive simulations show the analytical model is highly accurate. From the analytical model it is shown that for practical buffer configuration (e.g. buffer size larger than one), we can maximize the total throughput and reduce the packet blocking probability (due to limited buffer size) and the average queuing delay to zero by effectively controlling the offered load. The average MAC layer service delay as well as its standard deviation, is also much lower than that in saturated conditions and has an upper bound. It is also observed that the optimal load is very close to the maximum achievable throughput regardless of the number of stations or buffer size. Moreover, the model is scalable for performance analysis of 802.11e in unsaturated conditions and 802.11 ad hoc networks with heterogenous traffic flows.