• 한국정보처리학회논문지
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• 제7권2S호
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• pp.649-655
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• 2000

Real-time application programs have constraints which need to be met between media-data. These constraints represents the delay time ad quality of service between media-data to be presented. In order to efficiently describe the delay time and quality of service, a new synchronization mechanism is needed. Proposed paper is a dynamic synchronization that minimized the effects of adaptive transmission delay time. That is, the method meets the requirements of synchronization between media-dat by handling dynamically the adaptive waiting time resulted from variations of delay time. In addition, the mechanism has interval adjustment using maximum delay jitter time. This paper decreases the data loss resulted from variation of delay time and from loss time of media-data by means of applying delay jitter in order to deal with synchronization interval adjustment. Plus, the mechanism adaptively manages the waiting time of smoothing buffer, which leads to minimize the gap from the variation of delay time. The proposed paper is suitable to the system which requires the guarantee of high quality of service and mechanism improves quality of services such as decrease of loss rate, increase of playout rate.

• 대한전자공학회논문지TC
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• 제44권10호
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• pp.99-109
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• 2007

무선랜에서 QoS를 지원하기 위해 제안된 IEEE 802.l1e의 HCCA (HCF Controlled Channel Access)는 폴링에 의한 채널 제어 방식이다. 즉 HCCA는 중앙 제어 방식이기 때문에 자원을 분배하기 위한 스케줄링 알고리즘이 필요하며 IEEE 802.11e 표준에는 Reference 스케줄러가 제시되어 있다. Reference 스케줄러븐 폴링 리스트에 있는 모든 스테이션들을 동일한 주기로 폴링하기 때문에 잦은 폴링으로 인해 오버헤드 면에서 비효율적이며, TXOP (Transmission Opportunity)의 활용률 면에서도 낮다. 본 논문에서는 이러한 단점을 극복하고자 스테이션들의 MSI (Maximum Service Interval)에 따라 폴링 주기를 단계별로 나누어서 스케줄링하기 위한 트래픽 스케줄링 및 수락 제어 (admission control) 알고리즘을 제안한다. 제안하는 알고리즘에서는 스테이션들이 자시의 MSI와 가능한 비슷한 주기로 폴링되기 때문에 Reference 스케줄러에 비해 폴링 오버헤드가 감소하게 되며, TXOP 활용률도 증가하게 된다. 시뮬레이션을 통한 Reference 스케줄러와의 성능 비교는 제안된 알고리즘이 전체적인 전송률 면에서 더 높은 성능을 보이고 더 많은 수의 스테이션이 서비스가 가능함을 보여준다.

• Asian-Australasian Journal of Animal Sciences
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• 제19권1호
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• pp.26-30
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• 2006

The study was undertaken to investigate the validity of milk urea concentration as an index of the reproductive performances in crossbred Karan-Fries (Holstein Friesian${\times}$Tharparkar) cows under farm condition. Milk urea was analysed in noon milk samples (1200 to 1300 h) to interrelate with the interval from parturition to first service, number of insemination per conception, first service conception rate and service period. Milk progesterone (P4) was analysed in noon milk samples on the day 1, 10, 20 and 30 post insemination to study the effect of milk urea concentration on early embryonic mortality. The interval from parturition to first service was found significantly (p<0.01) higher ($77.2{\pm}5.5$ days) when milk urea concentration was ${\geq}63.4mg/dl$. The average milk urea concentrations (mg/dl) were found $42.1{\pm}2.5$, $47.9{\pm}1.5$ and $50.3{\pm}3.1$, respectively in cows that conceived at $1^{st}$, $2^{nd}$ and $3^{rd}$ insemination. However, the variation was not statistically significant. The first insemination conception rate was found significantly (p<0.05) higher (68.8%) when milk urea level was ${\leq}32.4mg/dl$. The service period was found significantly (p<0.05) higher ($125.4{\pm}8.8$ days) when milk urea concentration was ${\geq}45.1mg/dl$. The milk P4 level indicated that the cows, those were detected as non-pregnant on day 60 post insemination were initially pregnant but the pregnancy was terminated sometime during the day 30 to 60 post insemination. The study indicates that the milk urea values may be used as an index of reproductive performances in dairy herd when individual animals are not being monitored for nutritional status. The altered milk urea values may be utilised by the farmers as ready reference to rectify the protein and energy nutrition in cows to achieve the better reproductive performances in herd.

• 정신신체의학
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• 제29권1호
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• pp.11-16
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• 2021

연구목적 항정신병약물로 인한 QTc간격연장은 심각한 심실성 부정맥을 초래할 가능성 때문에 주의가 필요한 부작용이다. 하지만 현재까지 국내에서 항정신병약물에 의한 QTc간격연장에 대한 연구는 많지 않았다. 본 연구는 조현병 환자에서 QTc간격연장에 영향을 주는 인구학적 및 임상적 변수를 알아보고자 한다. 방 법 일 병원에 입원치료를 받았던 441명 조현병 환자들의 의무기록을 후향적으로 검토하여 QTc간격과 인구학적 및 임상적 변수들을 파악하였다. QTc간격에 영향을 주는 변수를 알아보기 위해 QTc간격을 종속변수로 하여 위계적 중다회귀분석을 수행하였다. 결 과 평균 QTc간격은 417.2±28.4 ms였다. 위계적 중다회귀분석 결과 항정신병약물 단기작용주사제의 사용이 QTc간격연장의 가장 강한 예측인자였다. 결 론 본 연구는 조현병 환자에서 항정신병약물 단기작용주사제 사용이 QTc간격연장에 영향을 줄 수 있으며 조현병 환자의 치료 시 항정신병약물 단기작용주사제 사용에 보다 주의를 기울여야 함을 시사한다.

• 한국국방경영분석학회지
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• 제12권2호
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• pp.68-81
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• 1986

This thesis studies the estimation from interarrival and service time data of the mean number of customers in service at time t for an $M/G/{\infty}$ queue. The assumption is that the parametric form of the service time distribution is unknown and the empirical distribution of twe service time is used in the estimate the mean number of customers in service. In the case in which the customer arrival rate is known the distribution of the estimate is derived and an approximate normal confidence interval procedure is suggested. The use of the nonparametric methods, which are the jackknife and the bootstrap, to estimate variability and construct confidence intervals for the estimate is also studied both analytically and by simulation.

• Journal of Information Processing Systems
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• 제15권2호
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• pp.440-448
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• 2019

The Internet of Things (IoT) is one of the main enablers for situation awareness needed in accomplishing smart cities. IoT devices, especially for monitoring purposes, have stringent timing requirements which may not be met by cloud computing. This deficiency of cloud computing can be overcome by fog computing for which fog nodes are placed close to IoT devices. Because of low capabilities of fog nodes compared to cloud data centers, fog nodes may not be deployed with all the services required by IoT devices. Thus, in this article, we focus on the issue of fog service placement and present the recent research trends in this issue. Most of the literature on fog service placement deals with determining an appropriate fog node satisfying the various requirements like delay from the perspective of one or more service requests. In this article, we aim to effectively place fog services in accordance with the pre-obtained service demands, which may have been collected during the prior time interval, instead of on-demand service placement for one or more service requests. The concept of the logical fog network is newly presented for the sake of the scalability of fog service placement in a large-scale smart city. The logical fog network is formed in a tree topology rooted at the cloud data center. Based on the logical fog network, a service placement approach is proposed so that services can be placed on fog nodes in a resource-effective way.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.222-231
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• 2003

After the reform of rail industry, a system to evaluate service qualities is required for the continuous improvement of railway service and the strength of competitiveness. This research provides evaluation categories and indices which are considered to be suited to the evaluation of rail service qualities. This study provides 4 categories and 11 indices to assess the rail service qualities: provision-operation interval/average operation speed, reliability-regularity/operation cancellation rate, safety- train usage term/facilities for the weak, client satisfaction- easiness of reserving and purchasing of tickets/comfort of queuing facilities/ kindness of train crews/ pleasantness of trains/provision of information, etc.

• Journal of Animal Science and Technology
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• 제44권2호
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• pp.191-200
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• 2002

본 연구는 1986년부터 1995년도 사이에 한우개량단지의 한우 암소에 대하여 조사된 번식성적에 근거하여 한우의 번식형질에 미치는 환경요인의 효과를 추정하기 위하여 실시하였으며, 분석된 결과를 요약하면 다음과 같다. 1) 평균능력에서 초종부일령은 466.11${\pm}$5.72일, 초임일령은 480.10${\pm}$6.15일, 초산일령은 742.79 ${\pm}$7.48일, 분만후 초종부일령은 64.97${\pm}$1.42일, 공태일수는 72.06${\pm}$1.73일, 번식간격은 355.93 ${\pm}$1.92일, 임신기간은 285.38${\pm}$0.42일 및 수태당 종부회수는 1.21${\pm}$0.02회였다. 2) 지역별 각 형질에 대한 범위는 초종부일령은 447.62${\pm}$5.94-490.72${\pm}$5.94일, 초임일령은 464.27${\pm}$6.38-505.20${\pm}$6.39일, 초산일령은 721.91 ${\pm}$ 7.85-772.75${\pm}$7.80일, 분만 후 초종부일령은 62.27${\pm}$1.55～68.97${\pm}$1.74일, 공태일수는 69.74${\pm}$ 1.97-74.36${\pm}$2.27일, 번식간격은 352.71${\pm}$2.18-359.64${\pm}$2.09일, 임신기간은 284.52${\pm}$0.42-286.04 ${\pm}$0.47일 및 수태당 종부회수는 1.11${\pm}$0.02-1.30 ${\pm}$0.02회였다. 3) 초종부일령은 혈통등록우가 가장 길었고 상위등록일수록 일령이 빨라지는 경향이 있 었다. 수태당 종부회수는 상위등록우로 갈수록 종부회수가 많게 추정되었다. 4) 분만후 초종부일수는 2산차에서 가장 길었으며 산차가 진행될수록 줄어드는 경향을 보였다. 수태당 종부회수는 산차가 진행될수록 적어지는 경향을 보였다. 5) 분만년도가 1987년부터 1995년까지 경과할수록 분만후 초종부일수, 공태일수 및 번식 간격이 길어지고 수태당 종부회수는 많아지는 경향이 있었다. 6) 분만후 초종부 일수, 공태일수 및 번식간격은 봄과 여름에 분만한 소들에서 가을과 겨울에 분만한 소들에 비하여 다소 짧게 추정되었다. 수태당 종부회수는 봄과 여름에 분만한 소들에 비하여 가을과 겨울에 분만한 소들에서 더 많은 경향이 있었다.

• 대기
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• 제24권2호
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• pp.197-206
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• 2014

The effects of different averaging operators and atmospheric stability on the turbulent fluxes are investigated using the vertical velocity, air temperature, carbon dioxide concentration, and absolute humidity data measured at 10 Hz by a 3-dimensional sonic anemometer and an open-path $CO_2/H_2O$ infrared gas analyzer installed at a height of 18.5 m on the rooftop of the Jungnang KT building located at a typical residential area in Seoul, Korea. For this purpose, 7 different averaging operators including block average, linear regression, and moving averages during 100 s, 300 s, 600 s, 900 s, and 1800 s are considered and the data quality control procedure such as physical limit check and spike removal is also applied. It is found that as the averaging interval becomes shorter, turbulent fluxes computed by the moving average become smaller and the ratios of turbulent fluxes computed by the 100 s moving average to the fluxes by the 1800 s moving average under unstable stability are smaller than those under neutral stability. The turbulent fluxes computed by the linear regression are 85~92% of those computed by the 1800 s moving average and nearly the same as those computed by 900 s moving average, implying that the adequate selection of an averaging operator and its interval will be very important to estimate more accurate turbulent fluxes at urban area.

• Asian-Australasian Journal of Animal Sciences
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• 제32권4호
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• pp.519-526
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• 2019

Objective: We determined the risk factors limiting first service conception (FSC) rate in dairy cows and their economic impact. Methods: Data were collected from 790 lactations regarding cow parity, peri- and postpartum disorders, body condition score (BCS), reproductive performance, and expenses associated with reproductive management (treatment, culling, and others). Initially, we identified the risk factors limiting FSC rate in dairy cows. Various biological and environmental factors, such as herd, cow parity, BCS at 1 month postpartum and first artificial insemination (AI), resumption of cyclicity within 1 month of calving, year, AI season, insemination at detected estrus or timed AI, peri- and postpartum disorders, and calving to first AI interval, were evaluated. Next, we evaluated the economic impact of the success or failure of FSC by comparing the expense associated with reproductive management until conception between cows that did or did not conceive at their first service. Results: Cows with BCS <3.0 had a lower probability of conceiving at first insemination (odds ratio [OR] = 0.64, p<0.05) than cows with $BCS{\geq}3.0$. Cows inseminated during summer were less likely to conceive (OR = 0.44, p<0.001) than cows inseminated during spring. Cows with peri- or postpartum disorders were less likely to conceive (OR = 0.55, p<0.001) than cows without disorders. Survival curves generated using MedCalc showed an 81 day extension in the mean interval between calving and conception in cows that failed to conceive over those that did conceive at first insemination. Cows failing conceive required additional expenditure on reproductive treatment ($55.40) and other management ($567.00) than cows that conceived at first insemination. Conclusion: Lower BCS, hot weather at first insemination, and peri- and postpartum disorders are risk factors limiting FSC, which result in an economic loss of $622.40 per dairy cow.