• Title/Summary/Keyword: elapsed time

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Analysis of a Controllable M/G/1 Queueing Model Operating under the (TN) Policy ((TN) 운용방침이 적용되는 조정가능한 M/G/1 대기모형 분석)

  • Rhee, Hahn-Kyou
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.37 no.1
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    • pp.96-103
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    • 2014
  • A steady-state controllable M/G/1 queueing model operating under the (TN) policy is considered where the (TN) policy is defined as the next busy period will be initiated either after T time units elapsed from the end of the previous busy period if at least one customer arrives at the system during that time period, or the time instant when Nth customer arrives at the system after T time units elapsed without customers' arrivals during that time period. After deriving the necessary system characteristics such as the expected number of customers in the system, the expected length of busy period and so on, the total expected cost function per unit time in the system operation is constructed to determine the optimal operating policy. To do so, the cost elements associated with such system characteristics including the customers' waiting cost in the system and the server's removal and activating cost are defined. Then, the optimal values of the decision variables included in the operating policies are determined by minimizing the total expected cost function per unit time to operate the system under consideration.

The EMG Measurement of Simple and Iterative Worker′s Muscle Fatigue (단순반복 근로자의 근육피로도에 관한 EMG분석)

  • 서승록;임완희
    • Journal of Korea Society of Industrial Information Systems
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    • v.6 no.3
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    • pp.79-86
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    • 2001
  • The CTD(Cumulative Trauma Disorder) as a new kind of occupational disease occurs mainly to workers on handling line under the highly-specialized industrial environments. This study took into account their exposure to Cumulative Trauma Disorders(CTD) by the utilization of EMG system, with respect to worker's muscle fatigue test according to fulfillment of iterative and simple task. The findings of this study were as follows : From the result of AEMG test analysis, worker's fatigue extent according to elapsed time of task was inclined to be increased continually. On the other hand, after its task ending, their fatigue extent was inclined to be decreased than before-circumstance of refractory brick lifting. The transference of MF(Median Frequency) and MPF(Mean Power Frequency) had highly significant difference between muscle fatigue and the elapsed time of work. Especially, their fatigue extent to erectorspinae and multifidus to lift firebrick was increased in the mean time. The transference of ZCR(Zero Crossing Rate) had considerable significant difference between muscle fatigue and the elapsed time of work. In short, as the work went of the muscle fatigue extent increased gradually. Thus, it can be concluded that the fatigue of erectorspinae and multifidus extent according to fulfillment of iterative and simple task is gradually being increased.

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Structural Safety Analysis on Car Body at Overturn (전복시 차체에 대한 구조 안전 해석)

  • Cho, Jae-Ung;Kim, Key-Sun;Lee, Eun-Jong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.1
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    • pp.32-37
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    • 2011
  • In this study, the changes of displacement and stress are investigated by structural analysis according to the thickness of car body in case of overturn. In case of 5 mm thickness, the maximum displacement of 7.5024 mm at its right ceiling and the maximum equivalent stress of 113.69 MPa at the left lower part are occurred on the elapsed time of 2 second. In case of 10 mm thickness, the maximum displacement of 1.2557 mm at its right ceiling and the maximum equivalent stress of 15.134 MPa at the left lower part are occurred on the elapsed time of 2 second. In case of 15 mm thickness, the maximum displacement of 0.426067 mm at its right ceiling and the maximum equivalent stress of 4.4842 MPa at the left lower part are occurred on the elapsed time of 2 second. As stress and displacement are uniformly distributed according to time in this case, the design of car body can be stabilized.

Dynamics of Nutrient and KDICical Constituents during Litter Decomposition (낙엽의 분해과정에 따른 영양염류 및 화학적 구성원의 동태)

  • Mun, hyeibg-Tae;Jae-Hoon Pyo
    • The Korean Journal of Ecology
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    • v.17 no.4
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    • pp.501-511
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    • 1994
  • Dynamics of nutrients, non-polar, water solubles, acid solubles and acid insolubles (lignin) in decomposing litter were investigated for 2 years in the oak, Quercus acutissima, and the pitch pine, Pinus rigida, stands in the vicinity of Kongju, Chungnam Province. Nitrogen and phosphorus conetrations in decomposing litter increased with time elapsed, however, potassium decreased rapidly within three months and then remined constant with time elapsed. Calcium concentration in needle litter during experimental period was lower than that of initial concentration in needle litter during experimental period was lower than that of initial concentration, and showed no significant variation with time elapsed. Calcium concentration in oak litter during the experimental period, however, were higher than that of initial concentration. Magnesium concentration in oak litter decreased repidly during six months, and then remaines constant thereafter. Annual amount of nitrogen, phosphorus, potassium, calcium and magnesium which returned to soil via litter decomposition in the oak and the pitch pine stands was $3.3g/m^2$ and $0.9g/m^2$ for N, $0.03g/m^2$ and $0.01g/m^2$ for P, $1.3g/m^2$ and $0.7g/m^2$ for K, $0.7g/m^2$ and $1.2g/m^2$ for Ca, $0.9g/m^2$ and $0.4g/m^2$ for Mg, respectively. Non-polar, and water- and acid-soluble fractions in decomposing litter decreased and lignin increased with time.

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Dose-Response Relationship between Catalase and Superoxide Dismutase Activity in Testes of Acutely Intoxicated Rats by Cadmium (급성 카드뮴중독시 랏트의 고환조직내 Catalase 및 Superoxide Dismutase 활성도와의 양-반응관계)

  • Park, Bo-Young;Park, Jung-Duck;Chung, Kyou-Chull
    • Journal of Preventive Medicine and Public Health
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    • v.21 no.2 s.24
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    • pp.295-306
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    • 1988
  • Dose-response relationship among blood cadmium concentrations, catalase and superoxide dismutase activities were studied with acutely intoxicated rats by cadmium. The Sprague-Dawley male rats to which single dose of $1{\sim}32mg/kg\;CdCl_2$ were administered into peritoneal cavity were sacrificed by decapitation at $3{\sim}36$ hours after the administration. Cadmium concentrations in blood increased significantly with dose of $CdCl_2$ administered and reached peak level at 3 hours later. Catalase activities in rats' testes were not correlated with esposure time elapsed after the administration in rats to which $1{\sim}2mg/kg\;of\;CdCl_2$ were administered, but they showed linear relationship with time in groups to which $4{\sim}32mg/kg\;of\;CdCl_2$ were administered. Cu, Zn-SOD activities in testes of acutely intoxicated rats by cadmium were not altered either by dosage or by time elapsed after the administration. Mn-SOD activities in the testes were also not influenced by dosage of $1{\sim}2mg/kg\;CdCl_2$, but remarkably inactivated by dosage of $4{\sim}32mg/kg\;CdCl_2$ with time elapsed after the administration. Neither catalase, Cu, Zn-SOD nor Mn-SOD activities of testes were correlated with blood cadmium concentrations in acutely intoxicated rats by cadmium.

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A Study on the Fluidity Retention of Cement Paste Added by Naphthalene Sulfonated Condensate and Polycarboxylic Acid Admixture (나프탈렌술폰산축합물과 폴리카르본산계 혼화제가 첨가된 시멘트 페이스트의 유동성 유지에 관한 연구)

  • 노재성;홍성수;김도수
    • Magazine of the Korea Concrete Institute
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    • v.7 no.5
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    • pp.189-199
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    • 1995
  • Naphthalene sulfonated condensate has been widely used as a superplasticizer for cement and concrete, but the application was limited due to its large slump loss with elapsed time. To complement this demerit of NSF, polycarboxylic acid copolymer from nlaleic anhydride and acryl~c acid(MA) was synthesized to retain the mobility of cement and concrete, and then mixed with NSF. The physical properties, such as fluidity, fluidityretention and rheology, were measured by applying these admixtures to cement paste as a function of elapsed time. And also compressive strength of mortar was measured with curing time. NIv-l and NM-2 containing 10, 20 wt% of MA respectively had a excellent fluidity and a fluidity- retention. In rheological property, the increases of shear stress and viscosity with elapsed time were delayed with the increasing of shear rate in cornparision with NSF only. The marked slump loss of cement paste could be controlled by these admixture. Also the added ainount of admixture and the ratio of water to cement affected these properties.

The Effects of Optical Cable Fault on Customer Complaints (광케이블 고장이 고객 불만에 미치는 영향 연구)

  • Jung, So-Ki;Cha, Kyoung Cheon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.2
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    • pp.325-333
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    • 2015
  • In this paper, we are aim to analysis the effects of optical cable fault on customer complaints. We considered several causes: the elapse time to allow repair from the optical cable fault, whether working day or not, seasonality and human error, external construction, optical cable cutting or core banding that is controllable causes and natural disasters, vehicle crash, fire that is uncontrollable causes. The results of analysis are as follows: First, customer complaints increase through indifferencial relationship when using the production function for the number of expected victims and elapsed time due to the optical cable fault. Second, not only the elapsed time but also controllable variables, human error, external construction, the core cut occurs, increased customer complaints due to optical cable faults.

Context Prediction Using Right and Wrong Patterns to Improve Sequential Matching Performance for More Accurate Dynamic Context-Aware Recommendation (보다 정확한 동적 상황인식 추천을 위해 정확 및 오류 패턴을 활용하여 순차적 매칭 성능이 개선된 상황 예측 방법)

  • Kwon, Oh-Byung
    • Asia pacific journal of information systems
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    • v.19 no.3
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    • pp.51-67
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    • 2009
  • Developing an agile recommender system for nomadic users has been regarded as a promising application in mobile and ubiquitous settings. To increase the quality of personalized recommendation in terms of accuracy and elapsed time, estimating future context of the user in a correct way is highly crucial. Traditionally, time series analysis and Makovian process have been adopted for such forecasting. However, these methods are not adequate in predicting context data, only because most of context data are represented as nominal scale. To resolve these limitations, the alignment-prediction algorithm has been suggested for context prediction, especially for future context from the low-level context. Recently, an ontological approach has been proposed for guided context prediction without context history. However, due to variety of context information, acquiring sufficient context prediction knowledge a priori is not easy in most of service domains. Hence, the purpose of this paper is to propose a novel context prediction methodology, which does not require a priori knowledge, and to increase accuracy and decrease elapsed time for service response. To do so, we have newly developed pattern-based context prediction approach. First of ail, a set of individual rules is derived from each context attribute using context history. Then a pattern consisted of results from reasoning individual rules, is developed for pattern learning. If at least one context property matches, say R, then regard the pattern as right. If the pattern is new, add right pattern, set the value of mismatched properties = 0, freq = 1 and w(R, 1). Otherwise, increase the frequency of the matched right pattern by 1 and then set w(R,freq). After finishing training, if the frequency is greater than a threshold value, then save the right pattern in knowledge base. On the other hand, if at least one context property matches, say W, then regard the pattern as wrong. If the pattern is new, modify the result into wrong answer, add right pattern, and set frequency to 1 and w(W, 1). Or, increase the matched wrong pattern's frequency by 1 and then set w(W, freq). After finishing training, if the frequency value is greater than a threshold level, then save the wrong pattern on the knowledge basis. Then, context prediction is performed with combinatorial rules as follows: first, identify current context. Second, find matched patterns from right patterns. If there is no pattern matched, then find a matching pattern from wrong patterns. If a matching pattern is not found, then choose one context property whose predictability is higher than that of any other properties. To show the feasibility of the methodology proposed in this paper, we collected actual context history from the travelers who had visited the largest amusement park in Korea. As a result, 400 context records were collected in 2009. Then we randomly selected 70% of the records as training data. The rest were selected as testing data. To examine the performance of the methodology, prediction accuracy and elapsed time were chosen as measures. We compared the performance with case-based reasoning and voting methods. Through a simulation test, we conclude that our methodology is clearly better than CBR and voting methods in terms of accuracy and elapsed time. This shows that the methodology is relatively valid and scalable. As a second round of the experiment, we compared a full model to a partial model. A full model indicates that right and wrong patterns are used for reasoning the future context. On the other hand, a partial model means that the reasoning is performed only with right patterns, which is generally adopted in the legacy alignment-prediction method. It turned out that a full model is better than a partial model in terms of the accuracy while partial model is better when considering elapsed time. As a last experiment, we took into our consideration potential privacy problems that might arise among the users. To mediate such concern, we excluded such context properties as date of tour and user profiles such as gender and age. The outcome shows that preserving privacy is endurable. Contributions of this paper are as follows: First, academically, we have improved sequential matching methods to predict accuracy and service time by considering individual rules of each context property and learning from wrong patterns. Second, the proposed method is found to be quite effective for privacy preserving applications, which are frequently required by B2C context-aware services; the privacy preserving system applying the proposed method successfully can also decrease elapsed time. Hence, the method is very practical in establishing privacy preserving context-aware services. Our future research issues taking into account some limitations in this paper can be summarized as follows. First, user acceptance or usability will be tested with actual users in order to prove the value of the prototype system. Second, we will apply the proposed method to more general application domains as this paper focused on tourism in amusement park.

Physicochemical Factors for Evaluating Freshness of Apple and Tomato (사과 및 토마토의 신선도 평가를 위한 물리화학적 인자 탐색)

  • 조용진;황재관
    • Journal of Biosystems Engineering
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    • v.23 no.5
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    • pp.473-480
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    • 1998
  • This study was performed to analyze the variation of various physicochemical factors related to the freshness of apple and tomato during post-harvest period. The total soluble solids content, uronic acid content, cell surface roughness. density, rupture deformation and rupture force were measured for 39 days at 7-day intervals for apple and for 11 days at 2-day intervals for tomato. respectively. The cell surface roughness of apple increased with the elapsed time, while the rupture force decreased. In case of tomato, uronic acid content, density and rupture deformation increased with the elapsed time whereas the rupture force decreased. Both apple and tomato exhibited the significant correlations among those physicochemical factors.

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Estimation of Seroconversion Dates of HIV by Imputation Based on Regression Models

  • Lee, Seungyeoun
    • Communications for Statistical Applications and Methods
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    • v.8 no.3
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    • pp.815-822
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    • 2001
  • The aim of this study is to estimate the seroconversion date of the human immunodeficiency virus(HIV) infection for the HIV infected patients in Korea. Data are collected from two cohorts. The first cohort is a group of "seroprevalent" patients who were seropositive and AIDS-free at entry. The other is a group of "seroincident" patients who were initially seronegative but later converted to HIV antibody-positive. The seroconversion dates of the seroincident cohort are available while those of the seroprevalent cohort are not. Estimation of seroconversion date is important because it can be used to calculate the incubation period of AIDS which is defined as the elapsed time between the HIV infection and the development of AIDS. In this paper, a Weibull regression model Is fitted for the seroincident cohort using information about the elapsed time since seroconversion and the CD4$^{+}$ cell count.The seroconversion dates for the seroprevalent cohort are imputed on the basis of the marker of maturity of HIV infection percent of CD4$^{+}$cell count.unt.

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