• Proceedings of the Korean Operations and Management Science Society Conference
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• 1993.04a
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• pp.49-56
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• 1993

We consider a B/G/1 queueing system 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. This system finds an application in the performance evaluation of the DQDB protocol which has been adopted as the standard protocol for IEEE 802.6 MAN.

• 순환기질환의공학회:학술대회논문집
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• 2002.11a
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• pp.50-51
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• 2002

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1999.04a
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• pp.536-536
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• 1999

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.2
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• pp.89-98
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• 2005

In this study, indoor VOCs concentration emitted from floor and furniture was measured after the installation of floor and furniture in a real residence. With the measured data, prediction method and predication equations for indoor concentration of each VOCs and BTEX were developed. The following conclusions were drawn from this study. First, according to the predicted results of concentration decrease of BTEX (benzene, toluene, ethylbenzene, m,p,o-xylene) after the installation of floor in a real residence, prediction equation can be expressed using exponential function. Second, in case of floor, more reliable prediction equation can be obtained by using cumulative value of indoor concentration than by using just hourly measured value directly. Indoor concentration of benzene can be expressed as $y=408.52(1­e^{-00031{\times}time})$ with $R^2$ of 0.94 which is significantly high value. Third, toluene showed the highest concentration in case of furniture installation indoors, and it needed the longest time for concentration decrease. However, other substances except toluene showed constant concentration throughout the measurement period. Fourth, in case of furniture installation indoors, prediction equation of toluene concentration decrease is estimated to be $y= 3616.3{\times}e^{(-0.1091{\times}time)}+513.96{\times}e^{(-0.0006{\times}time)}\;with\; R^2$ of 0.95 which is significantly high value.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.4061-4076
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• 2017

With the development of high-speed railway technologies, train velocities can now reach speeds up to 350 km/h, and higher in the future. In high-speed railway systems (HSRs), loss of communication can result in serious accidents, especially when the train is controlled through wireless communications. For to this reason, operators of Long Term Evolution for Railway (LTE-R) communication systems install eNodeBs (eNBs) with high density to achieve highly reliable communications. However, densely located eNBs can result in unnecessary frequent handovers (HOs) resulting in instability because, during every HO process, there is a period of time in which the communication link is disconnected. To solve this problem, in this paper, an HO scheme based on the maximum cell residence time (CRT) and adaptive time to trigger (aTTT), which are collectively called CaT, is proposed to reduce unnecessary HOs (using CRT estimations) and decrease HO failures by improving the handover command transmission point (HCTP) in LTE-R HSR communications.

• Korean Institute of Interior Design Journal
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• v.27 no.1
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• pp.109-116
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• 2018

Prairie style houses in first stages of Frank Lloyd Wright's architecture activity pay a leading role in the process of house modernization as reflecting social and economic circumstances of the time based on traditional house style of the States. Wright's first work after retiring from L. Sullivan's office, Winslow house in 1983 is pioneering work predicting prairie house. This is because this house has only one modern architecture language of Wright and follow no style prevailing of the time. So, a researcher analyse Winslow house within the framework of functional thinking and new formative value creation in the modernization process of western house. Through this, The goal of this study is to find out modern characteristics and the meaning of Winslow house in modernization process prior to the 1900s. Firstly, the followings are modern characteristics of Winslow house. First, Winslow house has original planning breaking from custom based on modern functional and reasonable thoughts, and has practical space reflecting resident's inner demand. Second, Winslow house has modern new plastic value through original exterior breaking from custom and integrated shape of inner-outer space and structure. Secondly, the followings are the meaning of Winslow house in modernization process prior to the 1900s. First, Wright intend to suggest directions of residence modernization through Winslow house before designing Prairie style houses in earnest. Second, mixing of modern vocabulary and eclecticism show a sign of residence modernization process on the time. Third, inner-outer flowing space, opening space concept of Winslow house has innovative meanings predicting spacial characteristics of modern architecture.

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1221-1225
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• 2007

A ${\beta}$-ionone-resistant mutant strain isolated from the red yeast Xanthophyllomyces dendrorhous KCTC 7704 was used for batch and continuous fermentation kinetic studies with glucose media in a 2.5-1 jar fermentor at $22^{\circ}C$ and pH 4.5. The kinetic pattern of growth and carotenoid concentration in the batch fermentations exhibited a so-called mixed-growth-associated product formation, possibly due to the fact that the content of intracellular carotenoids depends on the degree of physical maturation toward adulthood. To determine the maximum specific growth rate constant (${\mu}_m$) and Monod constant ($K_s$) for the mutant, glucose-limited continuous culture studies were performed at different dilution rates within a range of $0.02-0.10\;h^{-1}$. A reciprocal plot of the steady-state data (viz., reciprocal of glucose concentration versus residence time) obtained from continuous culture experiments was used to estimate a ${\mu}_m$ of $0.15\;h^{-1}$ and $k_s$ of 1.19 g/l. The carotenoid content related to the residence time appeared to assume a typical form of saturation kinetics. The maximum carotenoid content ($X_m$) for the mutant was estimated to be $1.04\;{\mu}g/mg$ dry cell weight, and the Lee constant ($k_m$), which was tentatively defined in this work, was found to be 3.0 h.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.6
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• pp.293-299
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• 2015

In Korea, it is the law that an apartment building which consists of over 100 households must have a ventilation system installed, either natural or mechanical. The heat recovery ventilator (HRV) is great way to reduce energy consumption. In this research we confirmed that based on site's construction plan and existing diffuser form, performed purpose CFD which simulates operation in temperatures below $-5^{\circ}C$ to circumstances of installation of an HRV in an apartment. As a result of this research we found that when the diffuser's aperture area was adjusted, the distribution of air temperature and residence time of air was more equally distributed and air temperature was higher, compared to when the diffuser has an identical aperture area. We also found that we are able to increase even more air temperature and air distribution of air temperature and residence time of air was even more equally distributed when run in parallel with a splitter damper.

• The Korean Journal of Food And Nutrition
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• v.29 no.4
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• pp.486-498
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• 2016

This study aimed to examine the health-related lifestyle habits and eating behaviors according to gender, ethnicity, and residence type of university students in Yanbian, China. Self-administered questionnaires were collected from 302 university students. Of the male students, 12.1% and 42.0% were in the underweight and overweight groups, respectively, and of the female subjects, 21.3% and 16.3%, were in those respective groups. More male than female students preferred the overweight body somatotype. In contrast, about 49.4% of female students were hoping to be underweight, and female students had more obvious difficulties with body somatotype perception, whereas their exercise frequency and time spent exercising per day were much less than those of male students. More Chinese than Korean-Chinese subjects exhibited regular eating habits, which included eating at the same time everyday and at the same frequency per day; these habits were, accompanied by generally healthier lifestyle habits regarding regularity of activity and exercise time. Self-boarding students had a significantly higher BMI ($23.7{\pm}5.1kg/m^2$) and were more likely to be overweight (43.5%) as compared to students who lived in a dormitory or with family. Salty taste was preferred by Chinese students more than Korean-Chinese students, and greasy taste was preferred by Korean-Chinese students as compared with Chinese students. This study found that inherent and environmental factors are related with the dietary behaviors of university students in Yanbian, China. Further studies are required to elucidate the structural elements of family life and the sociocultural factors associated with dietary behaviors in Yanbian.

• Clean Technology
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• v.24 no.4
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• pp.365-370
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• 2018

Oil shale is the sedimentary rock containing kerogen, which is one of the abundant unconventional fuel. In the pyrolysis process, oil, gas and coke are produced from the decomposition of oil shale. In this study, TGA and the continuous pyrolysis of oil shale have been investigated for the clean conversion of oil shale. Effects of reaction temperature and residence time on the pyrolysis conversion and oil production rate have been determined. Conversion of oil shale increases with increasing the reaction temperature and residence time. Optimum conditions for oil production were reaction temperature of $450{\sim}500^{\circ}C$ at the residence time of 30 min.