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        검색결과 52

        21.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In recent years, imbalanced data is one of the most important and frequent issue for quality control in industrial field. As an example, defect rate has been drastically reduced thanks to highly developed technology and quality management, so that only few defective data can be obtained from production process. Therefore, quality classification should be performed under the condition that one class (defective dataset) is even smaller than the other class (good dataset). However, traditional multi-class classification methods are not appropriate to deal with such an imbalanced dataset, since they classify data from the difference between one class and the others that can hardly be found in imbalanced datasets. Thus, one-class classification that thoroughly learns patterns of target class is more suitable for imbalanced dataset since it only focuses on data in a target class. So far, several one-class classification methods such as one-class support vector machine, neural network and decision tree there have been suggested. One-class support vector machine and neural network can guarantee good classification rate, and decision tree can provide a set of rules that can be clearly interpreted. However, the classifiers obtained from the former two methods consist of complex mathematical functions and cannot be easily understood by users. In case of decision tree, the criterion for rule generation is ambiguous. Therefore, as an alternative, a new one-class classifier using hyper-rectangles was proposed, which performs precise classification compared to other methods and generates rules clearly understood by users as well. In this paper, we suggest an approach for improving the limitations of those previous one-class classification algorithms. Specifically, the suggested approach produces more improved one-class classifier using hyper-rectangles generated by using Gaussian function. The performance of the suggested algorithm is verified by a numerical experiment, which uses several datasets in UCI machine learning repository.
        4,000원
        22.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of the study was to investigate the effects of incentive spirometry and Ujjayi breathing technique on the pulmonary function of smokers. Subjects were individuals who had a smoking habit of at least a year. Subjects were randomly divided into 3 groups: the incentive spirometry group (n=8), Ujjayi breathing technique (n=9), and a group applying both incentive spirometry as well as Ujjayi breathing technique (n=8). Each intervention was performed twice a day, 5 times a week, for a total of 8 weeks whereupon the change in pulmonary function was evaluated. A spirometer was used to measure FVC, FEV1, and FEV1/FVC. The survey used for this study included the Fagerström Test of Nicotine Dependence (FTND) and the Shortness of Breath Questionnaire (SOBQ). Study results for the comparison within groups showed that in the group that performed both the incentive spirometry and Ujjayi breathing technique, FEV1 improved with statistical significance (p<.05). Furthermore, within this comparison the FEV1/FVC improved with statistical significance. Comparison amongst the groups showed no statistically significant differences in all areas. Following, to effectively increase pulmonary function in young adult smokers, both incentive spirometry and Ujjayi breathing technique should be employed together.
        4,000원
        23.
        2017.10 구독 인증기관·개인회원 무료
        In the painting process of automotive factory, color changeover cost is incurred every time the color of vehicle is changed. To solve this problem, automotive company usually uses storage space such as Selectivity Banks(SB) or Car Rescheduling Storage and carries out sequence planning so that vehicles of the same color are consecutive, which is called Car Resequencing Problem (CRP). So far, research works for CRP has focused on algorithms finding optimal or approximated optimal solutions under the condition that the number of vehicles is fixed in SB. However, these results cannot be directly applied to the actual automotive paint shops since they have continuous flows of cars into SB to be handled in a day. Therefore, in this paper, we propose an efficient cyclic scheduling method that starts the painting process using the result of Accelerated Dynamic Programming (ADP) and then reapplies the ADP to the vehicles in SB for renewing the painting schedule whenever a certain number of vehicles is painted, represented as a threshold. To show the effectiveness of the proposed method, we performed a numerical experiment by designing system configurations, based onthe actual vehicle painting process, and proposed a good threshold that can reduce overall color changeover cost.
        24.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The global small and mid-sized display market is changing from thin film transistor-liquid crystal display to organic light emitting diode (OLED). Reflecting these market conditions, the domestic and overseas display panel industry is making great effort to innovate OLED technology and incease productivity. However, current OLED production technology has not been able to satisfy the quality requirement levels by customers, as the market demand for OLED is becoming more and more diversified. In addition, as OLED panel production technology levels to satisfy customers’ requirement become higher, product quality problems are persistently generated in OLED deposition process. These problems not only decrease the production yield but also cause a second problem of deteriorating productivity. Based on these observations, in this study, we suggest TRIZ-based improvement of defects caused by glass pixel position deformation, which is one of quality deterioration problems in small and medium OLED deposition process. Specifically, we derive various factors affecting the glass pixel position shift by using cause and effect diagram and identify radical reasons by using XY-matrix. As a result, it is confirmed that glass heat distortion due to the high temperature of the OLED deposition process is the most influential factor in the glass pixel position shift. In order to solve the identified factors, we analyzed the cause and mechanism of glass thermal deformation. We suggest an efficient method to minimize glass thermal deformation by applying the improvement plan of facilities using contradiction matrix in TRIZ. We show that the suggested method can decrease the glass temperature change by about 23% through an experiment.
        4,000원
        25.
        2016.04 구독 인증기관·개인회원 무료
        Parasitism of horsehair worm in mantids were investigated for two years, from 2012 and 2013. The mantids were collected from forty-nine sites from August to November. Twenty-one sites (42.9%) of the collected mantids were parasitized by horsehair worms. C. japonensis was recorded from T. angustipennis, T. aridifolia and C. fukuii. The C. japonensis parasitism of T. angustipennis and T. aridifolia were 27.0% and 10.7%, respectively. The infested number of C. japonensis was 1-9 per host. The body length of C. japonensis showed tendency to decrease with number of parasites, but not significantly different. Horsehair worms did not affect body, abdomen length and digestive system of host. However, egg possession of host was different, unparasitized T. angustipennis and T. aridifolia had more eggs (63.7%) than parasitized ones (2.6%). C. japonensis was parasitized as immature stage in late Aug. immature and adult stage in early Sept. and only adult in late Oct. Parasitism was the highest in late Sept.
        26.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, we consider curriculum mining as an application of process mining in the domain of education. The basic objective of the curriculum mining is to construct a registration pattern model by using logs of registration data. However, subject registration patterns of students are very unstructured and complicated, called a spaghetti model, because it has a lot of different cases and high diversity of behaviors. In general, it is typically difficult to develop and analyze registration patterns. In the literature, there was an effort to handle this issue by using clustering based on the features of students and behaviors. However, it is not easy to obtain them in general since they are private and qualitative. Therefore, in this paper, we propose a new framework of curriculum mining applying K-means clustering based on subject attributes to solve the problems caused by unstructured process model obtained. Specifically, we divide subject’s attribute data into two parts : categorical and numerical data. Categorical attribute has subject name, class classification, and research field, while numerical attribute has ABEEK goal and semester information. In case of categorical attribute, we suggest a method to quantify them by using binarization. The number of clusters used for K-means clustering, we applied Elbow method using R-squared value representing the variance ratio that can be explained by the number of clusters. The performance of the suggested method was verified by using a log of student registration data from an ‘A university’ in terms of the simplicity and fitness, which are the typical performance measure of obtained process model in process mining.
        4,200원
        27.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, scheduling problems with position-dependent processing times have received considerable attention in the literature, where the processing times of jobs are dependent on the processing sequences. However, they did not consider cases in which each processed job has different learning or aging ratios. This means that the actual processing time for a job can be determined not only by the processing sequence, but also by the learning/aging ratio, which can reflect the degree of processing difficulties in subsequent jobs. Motivated by these remarks, in this paper, we consider a two-agent single-machine scheduling problem with linear job-dependent position-based learning effects, where two agents compete to use a common single machine and each job has a different learning ratio. Specifically, we take into account two different objective functions for two agents: one agent minimizes the total weighted completion time, and the other restricts the makespan to less than an upper bound. After formally defining the problem by developing a mixed integer non-linear programming formulation, we devise a branch-and-bound (B&B) algorithm to give optimal solutions by developing four dominance properties based on a pairwise interchange comparison and four properties regarding the feasibility of a considered sequence. We suggest a lower bound to speed up the search procedure in the B&B algorithm by fathoming any non-prominent nodes. As this problem is at least NP-hard, we suggest efficient genetic algorithms using different methods to generate the initial population and two crossover operations. Computational results show that the proposed algorithms are efficient to obtain near-optimal solutions.
        4,300원
        28.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we propose an efficient two-phase heuristic policy, called an acceptance tolerance control policy, for Infrastructure as a Service (IaaS) cloud services that considers both the service provider and customer in terms of profit and satisfaction, respectively. Each time an IaaS cloud service is requested, this policy determines whether the service is accepted or rejected by calculating the potential for realizing the two performance objectives. Moreover, it uses acceptance tolerance to identify the possibility for error with the chosen decision while compensating for both future fluctuations in customer demand and error possibilities based on past decisions. We conducted a numerical experiment to verify the performance of the proposed policy using several actual IaaS cloud service specifications and comparing it with other heuristics.
        4,000원
        29.
        2014.06 구독 인증기관 무료, 개인회원 유료
        This study was carried out to analyze cone and seed developmental characteristics of the Pinus densiflora community distributed in the entire area of Mt. Gwanggyo in Suwon. As survey areas, the P. densiflora communities of two regions, which are 400 meters and 550 meters in altitudes above the sea level, were selected, and cone collection was conducted 10 times in total from April 12 to October 11, 2012. The result of cone and seed development survey showed that the size and growth rate of cone and seed was larger and faster in individuals of the community situated at an altitude of 400 meters than those at an altitude of 500 meters. The water content of the cone collected from at an altitude of 400 meters on October 11 was 35.9%, which is 38.3% lower than that of the cone at an altitude of 500m, but more rapid decrease in water was found. The number of cone opening days was 7.3 days in the community at an altitude of 400 meters, and 8.1 days at an altitude of 500 meters, showing that of the cone at an altitude of 400 meters is shorter. The seed separation from the cone showed the same pattern as in the reduction rate from the water content of the inner cone. The number of seeds in the cone and percentage of sound seeds was also greater and higher in th cone at an altitude of 400 meters than that at an altitude of 500 meters. Meanwhile, the maturation of the embryo, a part of seed of the cone between the two communities was observed to be similar to each other. The external size of the seed has hardly changed since July 10th, but the embryo inside the seed was found to be mature until August 7th.
        4,000원
        30.
        2014.04 구독 인증기관·개인회원 무료
        Horsehair worm parasitism of mantids was investigated for two years, 2012 and 2013. The mantids were collected from forty-nine sites from August to November. Mantids collected from twenty-one sites (42.9%) including Amur silver grass plantation at Samjang-myeon in Sancheong, Gyeongnam province were parasitized by horsehair worms. C. japonensis was recorded from T. angustipennis and T. aridifolia and C. fukuii, a newly recorded species in Korea, was isolated from T. aridifolia. C. japonensis was found from T. angustipennis and T. aridifolia collected from Gyeongnam province (Jinju, Sancheong, Sacheon, Uiryeong, Hapcheon, and Goseong) and Sangju, Gyeongsbuk province. C. fukuii was isolated from T. aridifolia collected from Gunwi, Gyeongbuk province and Yangpyeong, Gyeonggi province. The C. japonensis parasitism of T. angustipennis and T. aridifolia was 27.0% and 10.7%, respectively. The number of C. japonensis in a host was from one to nine, but most was one from a host. The body length of C. japonensis showed tendency to decrease with number of parasites, but not significantly different. Horsehair worms did not affect body and abdomen length and digestive system of host. However, egg possession of host was different, that is, unparasitized T. angustipennis and T. aridifolia. had more eggs (63.7%) than parasitized ones (2.6%).
        31.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, we consider a two-agent scheduling with sequence-dependent exponential learning effects consideration, where two agents A and B have to share a single machine for processing their jobs. The objective function for agent A is to minimize the total completion time of jobs for agent A subject to a given upper bound on the objective function of agent B, representing the makespan of jobs for agent B. By assuming that the learning ratios for all jobs are the same, we suggest an enumeration-based backward allocation scheduling for finding an optimal solution and exemplify it by using a small numerical example. This problem has various applications in production systems as well as in operations management.
        4,000원
        32.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, we propose a logical control-based actor-critic algorithm as an efficient approach for the approximation of the capacitated fab scheduling problem. We apply the average reward temporal-difference learning method for estimating the relative
        4,000원
        33.
        2010.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, we suggest a PLCS-based architecture and operation method for providing interoperability in SBA integrated collaborative environment. Specifically, the suggested architecture is based on the distributed collaborative environment which emplo
        4,000원
        35.
        2009.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        참기름은 높은 항산화활성 및 항암작용 등의 우수한 영양학적 가치를 지니는 반면 비싼 가격으로 인하여 가짜 참기름의 유통이 범람하여 이를 판별할 수 있는 분석 방법의 확립이 요구되는 실정이다. 따라서 본 연구에서는 질량분석기를 바탕으로 한 전자코를 이용하여 대두유가 혼합된 참기름을 제조하여 진위 판별을 시도하기위하여 각각의 유지를 전자코를 이용하여 분석, 통계처리하였다. 혼합 참기름의 휘발성 향기성분으로부터 생성되는 ion fragment 중 40-160 amu에서 각 시료 간에 차별성이 높은 fragment (m/z)를 선택하여 해당 intensity값을 판별 분석한 결과, 참기름 및 대두유는 뚜렷하게 구분되었다. 참기름 및 대두유, 옥수수유, 들기름을 각각의 순수한 상태로 향기성분 분석을 한 결과 서로 다른 위치에서 정확하게 분리됨을 알 수 있었고, 대두유와 옥수수유의 경우 타 기름과는 달리 순수한 공기 성분과 비슷한 위치에서 확인되는 것으로 휘발성 향기성분의 감응도가 상대적으로 낮은 것으로 판단된다. 미량의 대두유가 혼합된 참기름은 첨가된 대두유의 농도에 비례하여 제1판별함수값(DF1)과 높은 상관관계를 나타내었다. 참향후 참기름의 위조 여부를 검증하는 방법에 하나로 활용될 수 있을 것이다.
        4,000원
        37.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 유한용량 재진입 생산라인에서의 스케쥴링 문제에 대한 유전자적 접근 방법을 제안하였다. 알고리즘에서 사용되는 염색체의 구조는 워크스테이션의 버퍼레벨에 대한 모든 가능한 경우를 고려하여 정의되었으며, 염색체의 각 유전자에는 그에 대응되는 시스템 상태에서 우선 순위를 갖는 작업 단계의 값이 할당되도록 하였다. 또한, 제안된 알고리즘의 구현 방법으로서 워크스테이션의 버퍼와 프로세싱 자원을 할당할 때 작업 간 우선 순위를 고려하는 동시에 각 워크스
        4,000원
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