• Journal of Internet Computing and Services
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• v.5 no.1
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• pp.25-32
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• 2004

Mobile computing environment makes it possible for computing activities to be maintained during movement even if a user changes its network point of attachment. Mobile IP is a standard protocol designed to be used in such mobile computing environment. However, Mobile IP has a drawback to incur a lot of handoff delays and waste network resources, since CoA(Care of Address) registration packets need to go through a HA(Home Agent) first whenever a mobile node moves. To solve this long-standing problem, this paper proposes a new scheme that, for infra-domain movement, efficiently performs local handoff without notifying the HA Specifically, based on the notion of load balance, the proposed scheme allows every FA(Foreign Agent) in a domain to become the root FA(also known as domain FA) dynamically, thus distributing the registration task into many other foreign agents. The dynamic root assignment through load balancing ultimately leads to fast network response due to less frequent transmission of registration packets.

• Journal of Society of Preventive Korean Medicine
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• v.1 no.1
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• pp.137-148
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• 1997

The Serial Securities and the Social Welfare, as the national policy aimed at securing generals' lives, are the policies or systems for the stabilization in lift; especially of law-incomers and workers, for which the povernment has to establish the Social Security System. No wonder the Social Insurance System is a part of the Social Security System and the most important. The Social Insurance System, along with Public Assistance, is underlying the Social Security System. Social Security System includes medical insurance, industrial accident Compensation insurance, national pention insurance and employment insurance. The study is on 'The Oriental Medical Insurance and the Industrial Accident Compensation in the Social Security System' . The rate of industrial accident in Korea marks the highest rank in the world. for laborer, industrial accident do not merely mean the loss of health but the question of the right to live in terms of their loss of opportunity of life. The industrial accident compensation system should be established as the es post facto remedy system to guarantee the injured worker and his/her family's life. The oriental medical insurance system which began to operate in 1987 in Korea is based on unionism and divided into 3 parts; one part for the worker, a second part for the community inhabitants, and a third part for the public service personnel and private school personnel. Today the medical problem must be the most important social assignment to be considered. The medical system of contemporary industrial society has began greatly stood out in relief as a part of social welfare not emphasized on gainings of physicians. Accordingly systematization of the oriental medical insurance was strongly Pursued and it was developed to to the extent of entire nation insurance. Though the history of it is very short, most of the people are getting benefit from the insurance system by the social security system method. This study develops the Oriental Medical Insurance, the Workmen's Accident Compensation Insurance, the Pension System in relation to the industrial accident compensation of Employees, along with the ideas and principles of social insurance.

• Journal of the Korean Society of School Health
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• v.22 no.2
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• pp.157-167
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• 2009

Purpose : The purpose of this study is to explore the students injuries by analyzing the data which has been inputted by the emergency center of the cooperated hospitals and the 119 rescue party through the injury surveillance system in Cheonan city. Method : Students were divided into the elementary, middle, high school students with the 776 cases of children and teenagers(7-19years old) of injury surveillance system in Cheonan area from january to june in 2009. Frequency analysis and $x^2$-test was done to recognize the features of students injuries among the groups. The program to be used for the statistical analysis is SPSS 17.0. Result : Out of the injury incidence rate, the elementary school students(52.1%) are first, the high school students (24.9%) are second, the middle school students appear to be 23.1%. Male is about two times higher than female by 66.6% in the injury incidence. In terms of the injury mechanism, the injury(22.2%) by hit is the first, the traffic accident(21.5%) is the second, the slippery(16.8%) is followed. The injuries were occurred most largely at 16:00-20:00(33.4%), and the 33.6% of injury by daily leisure activity occurs at 16:00-20:00 chiefly. Conclusion : Analysis using the data of the injury surveillance system has some advantages compared to the previous research such as reliability and specification. To prevent the students injuries, not the individual problem but the social dimension should be acknowledged so that we can secure and promote the safety from the risk. Therefore, we must organize the role assignment and the cooperative network in the school, home and community.

• Journal of Engineering Education Research
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• v.19 no.5
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• pp.13-24
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• 2016

The purpose of this research is to examine the characteristics of team interaction according to the creativity of team members. Research subjects to achieve this purpose included 28 students who are in engineering education in the College of Education at A University in Daejeon and have taken robot-related courses. Through first and second MBTI, and TTCT tests, the final homogeneous and heterogeneous teams were formed, and an experimental study was conducted by developing team design activity assignment. The major research results were as follows. In terms of a comprehensive view on interaction frequency, both homogeneous team and heterogeneous team suggested had the highest frequency in suggesting opinions. However, each of the team members in the homogeneous team had different communication frequency among each other while each team member in the heterogeneous team had almost similar frequency. A microscopic analysis of the communication process of homogeneous team showed that the team members' roles were divided among each other in communication. Next, according to the microscopic analysis of the heterogeneous team's communication process, the team members exchanged opinions in the beginning, talked to themselves in words that were hard to understand the meanings, and they stopped having conversations in the end. Due to such decrease in communication, two team members could not solve the confusing state of being unable to understand each other's opinions and failed to complete their assignments. The microscopic analysis demonstrated that the homogeneous team had a smooth interaction, because when one team member suggested an opinion during a conversation, other team members agreed with it through a discussion. However, the members in the heterogeneous team experienced confusion as they could not understand each other's conversation and could not overcome this problem, leading to lack of conversations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.10
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• pp.593-600
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• 2014

OFDMA systems solves frequency selective fading problem and provides improved performance by optimal allocation of subcarriers and transmit power. Two-way relay systems provide improved spectral efficiency compared to that of the conventional half-duplex relay using bidirectional communications. In legacy OFDMA system such as WiBro, two-way DF relay utilization causes pilot re-assignment and impossibility of channel estimation and decoding at relay nodes by self-interference. In this paper, resource allocation schemes for legacy OFDMA systems with two-way DF relay are proposed. The proposed schemes allocate subcarriers considering destinations nodes which are connected to relay nodes as individual nodes which are directly connected to a base station. Subsequently, the proposed schemes compensate bandwidth loss due to orthogonal allocations by overlapped allocating unused subcarriers at other noes. Numerical simulations show that the proposed resource allocation schemes provide improved performance compared with orthogonal allocation.

• Structural Engineering and Mechanics
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• v.37 no.6
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• pp.671-684
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• 2011

Deciding on an optimal sensor placement (OSP) is a common problem encountered in many engineering applications and is also a critical issue in the construction and implementation of an effective structural health monitoring (SHM) system. The present study focuses with techniques for selecting optimal sensor locations in a sensor network designed to monitor the health condition of Dalian World Trade Building which is the tallest in the northeast of China. Since the number of degree-of-freedom (DOF) of the building structure is too large, multi-modes should be selected to describe the dynamic behavior of a structural system with sufficient accuracy to allow its health state to be determined effectively. However, it's difficult to accurately distinguish the translational and rotational modes for the flexible structures with closely spaced modes by the modal participation mass ratios. In this paper, a new method of the OSP that computing the mode shape matrix in the weak axis of structure by the simplified multi-DOF system was presented based on the equivalent rigidity parameter identification method. The initial sensor assignment was obtained by the QR-factorization of the structural mode shape matrix. Taking the maximum off-diagonal element of the modal assurance criterion (MAC) matrix as a target function, one more sensor was added each time until the maximum off-diagonal element of the MAC reaches the threshold. Considering the economic factors, the final plan of sensor placement was determined. The numerical example demonstrated the feasibility and effectiveness of the proposed scheme.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.1
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• pp.91-103
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• 2006

Given a bill of materials (BOM) tree T labeled by the breadth first search (BFS) order from node 0 to node n and a general network ${\Im}=(V,A)$, where V={1,2,...,m} is the set of production facilities and A is the set of arcs representing transportation links between any of two facilities, we assume that each node of T stands for not only a component. but also a production stage which is a possible stocking point and operates under a periodic review base-stock policy, We also assume that the random demand which can be achieved by a suitable service level only occurs at the root node 0 of T and has a normal distribution $N({\mu},{\sigma}^2)$. Then our integrated model of facility location problems and safety stock optimization problem (FLP&SSOP) is to identify both the facility locations at which partitioned subtrees of T are produced and the optimal assignment of safety stocks so that the sum of production cost, inventory holding cost, and transportation cost is minimized while meeting the pre-specified service level for the final product. In this paper, we first formulate (FLP&SSOP) as a nonlinear integer programming model and show that it can be reformulated as a 0-1 linear integer programming model with an exponential number of decision variables. We then show that the linear programming relaxation of the reformulated model has an integrality property which guarantees that it can be optimally solved by a column generation method.

• The KIPS Transactions:PartD
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• v.8D no.5
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• pp.516-572
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• 2001

Geographic Information System(CIS) deal with data which can potentially be useful for a wide range of applications. The information needed by each application can be vary, specially in resolution, detail level, application view, and representation style, as defined in the modeling phase of the geographic database design. To be able to deal with such diverse needs, GIS must offer features that allow multiple representation for each geographic entity of phenomenon. This paper addresses on the problem of formal definition of the objects and their relationships on the geographical information systems. The geographical data is divided into two main classes : geo-objects and geo-fields, which describe discrete and continuous representations of spatial reality. I studied the attributes and the relationship roles over geo-object and nongeo-object. Therefore, this paper contributed on the efficient design of geographical class hierarchy schema by means of formalizing attribute-domains of classes.

• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.35-44
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• 2007

Work-related musculoskeletal disorders (WMSDs) are a major problem in industries in which manual materials handling is performed by workers. To prevent these WMSDs, it is necessary to understand the muscular strength capability and use this knowledge to design job and selection and assignment of workers. Even though two-hands lifting activity of manual materials handling tasks are prevalent at the industrial site, many manual materials handling tasks which require the worker to perform one-hand lifting are also very common at the industrial site and forestry and farming. However, a few researches have been done for one-hand lifting activity of manual materials handling tasks. The objective of this study is to compare one-hand and two-hands lifting strength in terms of static and dynamic strength of the lifting activity for the ranging from the height of knuckle to elbow. It is shown in this study that the isometric lifting strength of one-hand is ranging from 54.7 to 63.3% of the one of two-hands. However, it is found that there is no significant difference between a person's isometric lifting strength for left-hand and right-hand. It is also shown that there is no significant difference between the peak force under the dynamic sub-maximal loading with one-hand and two-hands lifting activity. Similar results were obtained for the peak acceleration and peak velocity under the dynamic sub-maximal loading with one-hand and two-hands lifting activity. Isometric lifting strength at the height of knuckle was ranging from 2 to 3 times of the dynamic peak force during sub-maximal lifting. It is concluded that the dynamic peak forces under the sub-maximal loading are not highly correlated with the isometric lifting strength in similar postures.

• Journal of Korea Society of Industrial Information Systems
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• v.4 no.2
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• pp.62-72
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• 1999

We consider a Direct Input Output Manufacturing System(DIOMS) which has a munber of machine centers placed along a built-in Automated Storage/Retrieval System(AS/RS). The Storage/Retrieval(S/R) machine handles parts placed on pallets for the machine centers located at either one or both sides of the AS/RS. This paper deals with the operational aspect of DIOMS and determines the optimal operating policy by combining computer simulation and genetic algorithm. The operational problem includes: input sequencing control, dispatching rule of the S/R machine, machine center-based part type selection rule and storage assignment policy. For each operating policy, several different policies are considered based on the known research results. In this paper, using the computer simulation and genetic algorithm we suggest a method which gives the optimal configuration of operating policies within reasonable computation time.