• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.165-172
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• 2015

The class of Dynamic Positioning System is divided in 3 classes depending on its redundancy and reliability according to IMO and classification society. There are 3 DP classes such as DP Class 1, 2 and 3 according to IMO MSC/Circ. 645. Higher DP class vessel has higher reliability, since redundancy concept is applied to the DP vessel depending on its DP class and can operate more safely. There are not enough information about DP class notation, which are needed when a company builds a new or buys second hand DP vessel or modifies DP classes, even the Korean shipyard is building a lot of DP vessels now. Also, the practical case of DP vessel modification, which had been done in Korea, to meet DP notation of IMO and classification society, will be helpful for DP vessel modification and sales industry development in Korea as a new business. As such this research identified what kind of requirements need to be taken into account to be from DP class 1 to DP class 2. The real DP class modification case is used to identify the requirements of DP class upgrade. Through the FMEA the redundancy concept on power system, thruster system and DP control system need to apply for DP class upgrade. The power system have to keep its DP function even if just a single fault happens on the generator or switchboard. Also, the PMS is required to monitor and control power system. Ship's Surge, Sway and Yaw movements can be controlled by the remaining thruster system after a single thruster fails. Lastly, multiple installation of PRS, sensors and DP control system are required to keep DP ability after a single fault on the DP control systems.

• Journal of the Korean Institute of Rural Architecture
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• v.13 no.2
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• pp.47-54
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• 2011

According to the master plan of the Ministry of Education, Science and Technology, departmentalized class system will be extended to all general middle & high schools by 2014 with the exception only of those having less than 6 classes located in small cities in rural areas. Under departmentalized class system, according to class timetable, students need to move from classroom to another classroom and areas where homebases, lounges, media spaces, rest places, and etc. This study has been undertaken to provide architectural data required in planning for student & learning support space for schools operating departmentalized class system, by investigating and analyzing cases in use at schools operating the system in Chungbuk area. As departmentalized class system is increasingly introduced, student & learning support space should be understood newly as spaces indispensable for students.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.185-192
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• 2012

It is the concept of this paper to build up the convergence type of the total class service system, and the goal is to develop the education services, which are differentiated from existing digital textbooks and development tools. We establish developmental programs and convergence strategies from market analyses related to apps and digital education. Then this paper proposes 'E-Class Author Service System (ECA)' as an education service system based on the tablet PC. It is the convergence system of the app type of textbook development tool and class management system. Teachers can produce and develop class materials and textbooks using the app type of textbook development tool in ECA service system. They can also add necessary functions from the class management system for efficient class progress. ECA improves the interaction and communication between a teacher, student and parents in the sever-based network. This study expects that ECA will achieve prior occupation of the app market as an educational app development tool and reduce private education expenses.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.4
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• pp.820-822
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• 2010

Mobile WiMAX system provides various classes of traffic such as real-time and non-realtime services. These services have different QoS requirements and the QoS aware scheduling has been an important issue. Although many of scheduling algorithms for various services in OFDMA system have been proposed, it is needed to be modified to be applied to Mobile WiMAX system. Since Mobile WiMAX supports five kinds of service classes, it is important to take QoS characteristics of each class into consideration. In this paper, we propose an efficient packet scheduling algorithm to support QoS of each class. Proposed scheme selects a service class first considering QoS Characteristics of each class and choose an appropriate user in the selected class. Simulation results show that the proposed algorithm has better performance than the other algorithm.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.12-22
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• 1999

Operation of an electromagnetic shaker system using a Class-D amplifier may cause unacceptable electromagnetic interference to another electronic system, requiring the user to take whatever steps are necessary to correct the interference. A differential amplifier in a Class-D amplifier is used to decrease the effect of a common-mode noise voltage in a shaker system. To prevent a ground loop, a transformer is inserted in another shaker system. These methods show reduction of the unwanted vibration which has occurred before. A transformer in a charge amplifier was used to prevent a ground loop in a shaker system using a Class-AB amplifier a few years ago, but it was susceptible of noise in a shaker system using a Class-D amplifier. Hence we corrected a ground loop between a charge amplifier and a vibration control/analysis system without a transformer. The usefulness of this approach is illustrated by the results of experiments.

• Journal of the Korean Institute of Educational Facilities
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• v.2 no.3
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• pp.31-38
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• 1995

The paper is to evaluate existing school building system with respect to students' comforts in the class room in Korea. This paper compared three styles of different school building system builted during last 20 years. Using statistical analysis, at first, the paper found that box-style structure is efficient for sustaining heat in the class room because it is compactly constructed. Secondly, air conditioning in the class room is important factor affected students' comforts in the summer time and for the smog occurring in the heating class room. Thirdly, we should compactly construct school building because the compactiveness of building components is important factor for student comforts. Fouthly, heating system in the class room should be changed. The system using gas or electricity insteded of coals should be introduced in the class room for the smog of the stove in winter time and for freshness in summer time.

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.505-516
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• 2007

In this paper, we provide some fundamental properties and basic theoretical results of K-class-based dedicated storage policy in a unit load system assuming the constant-space assumption that the number of storage locations for a class is not the maximum aggregate inventory position for a class but the sum of space requirement for products assigned to the class. The main theorem is that there exists a (K+1) -class-based storage layout whose expexted single command (SC) travel time is not greater than that of a K-class-based storage layout, i.e, $E(SC^*_{K+1}){\leq}E(SC^*_K)\;for\;K=1,{\cdots}$, (n-1).

• Journal of Engineering Education Research
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• v.8 no.4
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• pp.5-19
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• 2005

Computer based teaming system has considerable influence upon teaching technique and teaming efficiency. It is possible to make a learner-oriented teaching in the online learning system. In this case, it can provide easily and immediately learner with various information that relate to class status, for example, attendance, examination score and so on. In the case of conventional off-line education, however, it is inefficient to provide the information of class status for learners compared with on-line system. In this paper, we propose a monitoring system of class status which can provide various information of teaming status for learners, instructors and advisors. It is useful to advise student's course work and job. The main purpose of this system is to prepare a monitoring system of class status on a web based e-class system. It achieves self-monitoring systems which provide a feedback data as a result of class for students.

• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.133-138
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• 2002

In this paper, we model a two-server queueing system with priority, to which we put a restriction of the number of servers for each customer class. A group of customers is divided into two different classes. The class 1 customers has non -preemptive priority over class 2 customers. We use the method of PGF depending on the state of server We find the PGF of the number of customers in queue, server utilization, mean queue length and mean waiting time for each class of customers.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.5
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• pp.31-38
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• 2002

In this paper, we model a two-server queueing system with priority, to which we put a restriction on the number of servers for each customer class. customers are divided into two different classes. Class 1 customers have non-preemptive priority over class 2 customers. They are served by both servers when available but class 2 customers are served only by a designated server. We use a method of generating function depending on the state of servers. We find the generating function of the number of customers in queue, server utilization, mean queue length and mean waiting time for each class of customers.