• Journal of the Korean Operations Research and Management Science Society
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• v.18 no.1
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• pp.119-126
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• 1993

We study a manufacturing process that is quite common in semiconductor wafer fabrication of semiconductor chip production. A machine is used to process a job consisting of J wafers. Each job requires a setup, and the i$_{th}$ setup for a job is sucessful with probability P$_{i}$. The setup is prone to failure, which results in the loss of expensive wafers. Therefore, a tiral run is first conducted on a small batch. If the set up is successful, the test is passed and the balance of the job can be processed. If the setup is unsuccessful, the exposed wafers are lost to scrap and the mask is realigned. The process then repeats on the balance of the job. We call this as send-ahead policy and consider general policies in which the number of wafers that are sent shead depend on the cost of the raw wafer, the sequence of success probabilities, and the balance of the job. We model this process and determine the expected number of good wafers per job,the expected time to process a job, and the long run average throughput. An algorithm to minimize the cost per good wafer subject to a demand constraint is provided.d.d.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.3
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• pp.289-300
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• 2003

Traditional kernel-level communication systems for clusters are dependent upon computing platforms. Futhermore, they are not easy to use and do not provide various functions for clusters. This paper presents an architecture and various implementation issues of a kernel-level communication system, KCCM(Kernel level Cluster Communication Module), for linux cluster. The KCCM provides asynchronous communication services as well as standard synchronous communication services using send and receive. The KCCM also automatically detects and recovers connection failures at runtime. This allows programmers to use KCCM when they build mission critical applications over TCP-based connection-oriented communication environments. Having developed using standard socket interfaces, it can be easily ported to various platforms. The experimental results show that the KCCM provides good performance for asynchronous communication patterns.

• Journal of Computing Science and Engineering
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• v.5 no.4
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• pp.324-330
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• 2011

To avoid collisions, IEEE 802.11 medium access control (MAC) uses predetermined inter-frame spaces and the random back-off process. However, the retransmission strategy of IEEE 802.11 MAC results in considerable time wastage. The hidden node problem is well known in wireless networks; it aggravates the consequences of time wastage for retransmission. Many collision prevention and recovery approaches have been proposed to solve the hidden node problem, but all of them have complex control overhead. In this paper, we propose a fast retransmission scheme as a recovery approach. The proposed scheme identifies collisions caused by hidden nodes and then allows retransmission without collision. Analysis and simulations show that the proposed scheme has greater throughput than request-to-send and clear-to-send (RTS/CTS) and a shorter average waiting time.

• Journal of Arbitration Studies
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• v.9 no.1
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• pp.367-390
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• 1999

The basic requirements for conducting electronic commerce include confidentiality, integrity, authentication and authorization. Cryptographic algorithms, make possible use of powerful authentication and encryption methods. Cryptographic techniques offer essential types of services for electronic commerce : authentication, non-repudiation. The oldest form of key-based cryptography is called secret-key or symmetric encryption. Public-key systems offer some advantages. The public key pair can be rapidly distributed. We don't have to send a copy of your public key to all the respondents. Fast cryptographic algorithms for generating message digests are known as one-way hash function. In order to use public-key cryptography, we need to generate a public key and a private key. We could use e-mail to send public key to all the correspondents. A better, trusted way of distributing public keys is to use a certification authority. A certification authority will accept our public key, along with some proof of identity, and serve as a repository of digital certificates. The digital certificate acts like an electronic driver's license. The Korea government is trying to set up the Public Key Infrastructure for certificate authorities. Both governments and the international business community must involve archiving keys with trusted third parties within a key management infrastructure. The archived keys would be managed, secured by governments under due process of law and strict accountability. It is important that all the nations continue efforts to develop an escrowed key in frastructure based on voluntary use and international standards and agreements.

• Convergence Security Journal
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• v.6 no.3
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• pp.37-47
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• 2006

In this research, We connect the terrestrial magnetism sensor of the Philips to a bluetooth communication system and measured 360 degree of the azimuth change the angle with an incline of 5 degrees to an order direction. The value of the azimuth to be measured sent to the Bluetooth communication system and analyzed the measuring value in the 100m as moved. Using the bluetooth, we could send the measuring value of the azimuth without the bearing error in the plain without an electric wave obstacle within a distance in straight line 100M. We got the value of the azimuth have 98% reliability to maintain at a level with the terrestrial magnetism sensor. Based on this research. We send the measuring value of the azimuth which the accuracy is improved to a mobile intelligent robot moving a land inclined equipped with this system and can track the azimuth of it.

• The Journal of Information Technology
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• v.4 no.2
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• pp.1-23
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• 2001

The purpose of this paper is to study the send and receive of the Message in the Bolero System. Bolero System is the business processes and methods, together with the digital information system, which are provided by Bolero International for communicating Messages and Documents and facilitating business transactions, as well as the Bolero Rulebook and Operating Rules governing their use. The advantage of bolero.net include speed, cost and efficiency. First, bolero.net moves cirtical information and transactions more quickly than paper can move. Second, a message costs much less to transmit through bolero.net than via couriers and other paper means. Third, because bolero.net logs and tracks all transactions centrally, less data gets lost and fewer data entry errors occur. Bolero International is the certifier for all certificates used in the Bolero System at present. It takes significant responsibility and liability for the certificates that it issues in each Operational Service Contract. In the future, Bolero International may devolve the task of serving as certifier to one or more other qualified institutions.

• Journal of Mechanical Science and Technology
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• v.20 no.7
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• pp.972-980
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• 2006

In general, to send out natural gas via a pipeline network across the nation in LNG terminal, high-pressure cryogenic pump supply highly compressed LNG to high-pressure vaporization facilities. The Number of cryogenic pumps determined the send-out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high vibration at cryogenic pumps-motor system in LNG terminal, vibration spectrum analysis and motor current signature analysis have been performed together. Through the analysis, motor rotor bar problems are estimated by the vibration analysis and confirmed by the current analysis. So, it is demonstrated through the case study in this paper, how performing vibration analysis and current signature analysis together can reliable diagnosis rotor bar problems in pump-motor system.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.1
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• pp.37-45
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• 2015

As of June 2014, the rate of mobile internet users aged 6 and over is estimated at 98.3% (up by 2.8%p from the previous year). The vast majority of the teens (99.7%), the 20s (99.8%), the 30s (99.8%), and the 40s (98.1%) answer they use the smart phone. The existing notice methods have utilized noticeboard in the apartment. It is difficult to support real-time notice. The App has a merit to be accessed in anywhere, so that it is quite suitable for services requiring real-time support. This paper describes a development of apartmenrt notice and decision-making service using smart phone. We study previous researches about apartmenrt notice Apps. Then, we described the notice flow diagram and decision-making flow diagram. Apt admin sends the important notice message to residents using apt notice app in real-time. Apt admin writes the decision item in the admin web site. It pushes decision item to residents using apt notice app in real-time. The residents vote and send it to Apt admin. Apt admin counts the votes and send the collect the vote result to to residents.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.33-40
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• 2004

IPv6 defines relation between surrounding node using Neighbor Discovery protocol. Used Neighbor Discovery messages, grasp surrounding node, include important informations about network. These network information outcrops can give rise in network attack and also service that use network will paralysis. Various kinds of security limitation was found in Present Neighbor Discovery protocol therefore security function to supplement this problem was required. In this thesis, Secure Neighbor Discovery protocol that add with suity function was design and embody by CGA module and SEND module.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.51-53
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• 2006

This paper proposes a portable ECG monitoring system, which integrates uptodate PDA and RF communication technology. The aim of the study is to acquire the subject's biomedical signal without any constraint. It has two types of transmission mode, which are total signal transmission mode and HR(heart rate)/SC(step count) transmission mode. In audition, wireless communication technology uses Zigbee Wireless PAN and can work in low-power mode, which is one of the advantages of ZiBbee communication technology. The developed system is composed of a transmitter and a receiver. The transmitter has three-axial acceleration sensor. ECG amplifier and Zigbee communication controller. In total signal transmission mode, it can send data 50 packets per second whose transmission speed corresponds to 300 ECG samples and 60 acceleration samples. In HR/SG transmission mode, it can calculate heart rate from EEG data with 216 samples per second and step count from acceleration data and send a packet every cardiac cycle. The receiver forwards the received data to PDA, where the data can be stored and displayed. Therefore, the developed device enables to continuous monitoring for Activities of Daily Living(ADL). Also, this method will reduce medical costs in the aged society.