• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.361-370
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• 2004

All active nudes which have no physically direct connection with each other in If network must be able to compose and manage network topology Informations. Besides one active program can be performed by the active nodes when every active packet for this program is transmitted without any loss of packets. Also the active packets should be transmitted effectively to minimize the transmission delay and securely from threatens. In this thesis, the discovery scheme of active nodes is adapted for active nodes in IP networks to compose and manage the topology information. The scheme for the efficient, reliable and secure transmission of active packets is also proposed. The sequence number is assigned to every active packet. If a receiver detects the loss of active packet checking the sequence number, the receiver requests the retransmission of the lost packet to the previous active node. kiter receiving an active packet and adapting security and reliability schemes, intermediate active nodes not only copy and send the Packet Instantly but also apply some suity mechanisms to it. And the active packet transmission engine is proposed to provide these transmission schemes The simulation of the adapted active node discovery scheme and the proposed active packet transmission engine is performed. The simulation results show that the adapted active node discovery scheme is efficient and the proposed active engine has the low latency and the high performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.96-103
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• 2000

The voice traffic is one of the most important real-time objects in WATM(Wireless Asynchronous Transfer Mode) networks. In this paper, we propose a new MAC(Medium Access'Control) protocol for the efficienttransmission of voice traffic over WATM networks in the multimedia environment and compare the performanceto existing similar protocols. The new protocol separates the reservation slot period for voice and that for data toguarantee some level of QoS(Quality of Service) in voice traffic. This is denoted by a slot assignment functiondepending on the frame size. According to the characteristics of voice traffic which is repeatedly in silent states,the protocol allocates voice reservation request slots dynamically with respect to the number of silent(off state)voice sources and also sends the first block of talkspurt restarted after silent period with a reservation requestslot to reduce the access delay.The simulation results show that the proposed protocol has better performance than Slotted Aloha in bandwidthefficiency, and can serve a certain level of QoS by the given slot assignment function even when the number ofvoice terminals varies dynamically. This means we can observe that the new MAC protocol is much better thanthe NC-PRMA(None Collision-Packet Reservation Multiple Access) protocol.

• Journal of the Korea Society of Computer and Information
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• v.16 no.6
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• pp.165-178
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• 2011

A gigantic ship is constructed by assembling various types of ship blocks, each block being made by cutting and piecing the steel-plates together. The steel-plate piling process as the initial stage of ship construction sorts and manages the steel-plates according to the ship blocks that the steel-plates are used to make. The steel-plate piling process poses some problems such as process delay due to piling errors, safety vulnerability due to the handling of extra heavy-weight objects, and the uncertainty of work plan due to lack of information management in the pile spaces. We constructed a steel-plate piling process system based on the context-aware computing to resolve such problems. We built simulation system that can simulate the piling process and then established a smart space within the system by using tags, sensors and a real-time location system in order to collect context information. Workers receive an appropriate or intelligent service from the system.

• Sleep Medicine and Psychophysiology
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• v.6 no.1
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• pp.46-51
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• 1999

Objectives: Patients with premenstrual dysphoric disorder(or PMDD) have impairments of the social, occupational or academic function due to psychological or somatic symptoms, which have the characteristic pattern of symptom exacerbation in the week before menses begin and remission shortly after the onset of menses. In the chronobiological view, many researchers have assumed that the etiology of PMDD is the advanced circadian rhythm. It has been suggested that light has a therapeutic effect on PMDD, because evening light results in phase delay of circadian rhythm through the biochemical changes including melatonin. Methods: The authors investigated the therapeutic effect of light therapy on four patients with prospectively diagnosed PMDD by DSM-IV criteria using clinical psychiatric interview, Premenstrual Assessment Form(PAF) and Daily Rating Form(or DRF). In the evening(6:30pm-8:00pm), the 2,500 lux light administered for seven consecutive days during the symptomatic late luteal phase of menstrual cycle. Beck Depression Inventory(or BDI), Hamilton Rating Scale for Depression(or HAM-D), Spielberg State Anxiety Inventory(or SA), and DRF were evaluated before and after seven days of light therapy. Results: Premenstrual symptoms of PMDD could be effectively treated with the evening bright light therapy, especially in PMDD patients with atypical symptoms. In addition, the light therapy seemed to more effective on the psychologic symptoms than the somatic symptoms of PMDD. There was no significant side-effect of light therapy, except the transient and mild eye-strain in one case. Conclusions: In spite of the results of limited data from our clinical trial, the authors suggest that the potential use of light therapy as an alternative to the pharmacological management of patients with PMDD.

• The Journal of the Korean dental association
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• v.53 no.1
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• pp.36-46
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• 2015

Objectives: The objective of this work was to investigate the hospital nursing care of oral and maxillofacial health in jeju province. Methods: 438 Registered nurses(RN) who were working at each of secondary hospitals in Jeju province had responded to the questionnaire. The data were analyzed via frequency analyses and one-way ANOVA to assess the state of RN on hospital nursing care of oral and maxillofacial health. Results: The class of education on density in formal density that marked '0 hour' and '1-3 hours' were 73.5% and 19.9%, respectively. The class of refresher training on density that marked '0 hours' and '1-3 hours' were 92.9% and 6.6%, aggregately 99.5%. The nursing education on appearance after tumor of maxillofacial area that marked 'formal education' and 'none' were 45.2% and 52.1%, respectively. The score of question 'function, effect and side effect of hexamedin gaggle' was $2.68{\pm}0.95$ by Likert 5-point scale. Likewise, the scores were $2.82{\pm}0.88$ on question 'management of removal denture', $2.83{\pm}0.95$ on question 'preventive dental treatment before anticancer therapy', $2.88{\pm}0.86$ on question 'function of saliva', $2.96{\pm}0.99$ on question 'oral management of tube feeding patient', $3.13{\pm}1.00$ on question 'bacterial endocarditis from oral microflora', $3.36{\pm}0.89$ on question 'dysphagia' and $3.62{\pm}1.03$ on question 'aspiration pneumonia'. RN replied that 'lack of knowledge' and 'delay of cooperation' formed 53.7% and 33.3% respectively, on question 'problem in dental consultation other diseased patient'. Conclusions: From this study, it is necessary for RN and student of nursing science to be educated on the oral and maxillofacial nursing. Authors suggest further co-study and nation-wide research.

• Journal of Biomedical Engineering Research
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• v.21 no.3 s.61
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• pp.261-271
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• 2000

The present study investigated flow dynamics of a two-dimensional abdominal aortic bifurcation model under sinusoidal flow conditions considering wall motion. impedance phase angle(time delay between pressure and flow waveforms), and non-Newtonian fluid using computational fluid dynamics. The wall shear stress showed large variations in the bifurcated region and the wall motion reduced amplitude of wall shear stress significantly. As the impedance phase angle was changed to more negative values, the mean wall shear stress (time-averaged) decreased while the amplitude (oscillatory) of wall shear stress increased. At the curvature site on the outer wall where the mean wall shear stress approached zero. influence of the phase angle was relatively large. The mean wall shear stress decreased by $50\%$ in the $-90^{\circ}$ phase angle (flow wave advanced pressure wave by a quarter period) compared to the $0^{\circ}$ phase angle while the amplitude of wall shear stress increased by $15\%$. Therefore, hypertensive patients who tend to have large negative phase angles become more vulnerable to atherosclerosis according to the low and oscillatory shear stress theory because of the reduced mean and the increased oscillatory wall shear stresses. Non-Newtonian characteristics of fluid substantially increased the mean wall shear stress resulting in a less vulnerable state to atherosclerosis.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.1
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• pp.123-133
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• 2018

Cyber-Physical System (CPS) is a system in which a physical system and a cyber system are strongly integrated. In order to operate the target physical system stably, the CPS constantly monitors the physical system through the sensor and performs control using the actuator according to the current state. If a malicious attacker performs a forgery attack on the measured values of the sensors in order to conceal their attacks, the cyber system operated based on the collected data can not recognize the current operation status of the physical system. This causes the delay of the response of the automation system and the operator, and then more damage will occur. To protect the CPS from increasingly sophisticated and targeted attacks, countermeasures must be developed that can detect stealthy deception attacks. However, in the CPS environment composed of various heterogeneous devices, the process of analyzing and demonstrating the vulnerability to actual field devices requires a lot of time. Therefore, in this study, we propose a method of constructing the experiment environment of the PLCitM (PLC in the middle) which can verify the performance of the techniques to detect the CPS stealthy deception attack and present the experimental results.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.457-463
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• 2015

A gas turbine engine plays an important role as a prime mover that is used in the marine transportation field as well as the space/aviation and power plant fields. However, it has a complicated structure and there is a time delay element in the combustion process. Therefore, an elaborate mathematical model needs to be developed to control a gas turbine engine. In this study, a modeling technique for a gas generator, a PLA actuator, and a metering valve, which are major components of a gas turbine engine, is explained. In addition, sub-models are obtained at several operating points in a steady state based on the trial running data of a gas turbine engine, and a method for controlling the engine speed is proposed by designing an NPID controller for each sub-model. The proposed NPID controller uses three kinds of gains that are implemented with a nonlinear function. The parameters of the NPID controller are tuned using real-coded genetic algorithms in terms of minimizing the objective function. The validity of the proposed method is examined by applying to a gas turbine engine and by conducting a simulation.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.363-372
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• 2000

The present study investigated flow dynamics of a straight elastic blood vessel under sinusoidal flow conditions in order to understand influence of wall motion and impedance phase angle(time delay between pressure and flow waveforms) on wall shear stress distribution using computational fluid dynamics. For the straight elastic tube model considered in the our method of computation. The results showed that wall motion induced additional terms in the axial velocity profile and the pressure gradient. These additional terms due to wall motion reduced the amplitude of wall shear stress and also changed the mean wall shear stress. Te trend of the changes was very different depending on the impedance phase angle. As the wall shear stress increased. As the phase angle was reduced from 0$^{\circ}$to -90$^{\circ}$for ${\pm}$4% wall motion case, the mean wall shear stress decreased by 10.5% and the amplitude of wasll shear stress increased by 17.5%. Therefore, for hypertensive patients vulnerable state to atherosclerosis according to low and oscillatory shear stress theory.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.100-109
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• 2019

Maintainability indicates the extent to which maintenance can be done easily and quickly. The consideration of maintainability is crucial to reduce the operation and support costs of weapon systems, but if the maintainability is evaluated after the prototype production is done and necessitates design changes, it may increase the cost and delay the schedule. The evaluation should verify whether maintenance work can be performed, and support the designers in developing a design to improve maintainability. In previous studies, the maintainability index was calculated using the graph theory at the early design phase, but evaluation accuracy appeared to be limited. Analyzing the methods of evaluating the maintainability using fuzzy logic and 3D modeling indicate that the design of a system with good maintainability should be done in an integrated manner during the whole system life cycle. This paper proposes a method to evaluate maintainability using SysML-based modeling and simulation technique and fuzzy logic. The physical design structure with maintainability attributes was modeled using SysML 'bdd' diagram, and the maintainability was represented by an AHP matrix for maintainability attributes. We then calculated the maintainability using AHP-based weighting calculation and fuzzy logic through the use of SysML 'par' diagram that incorporated MATLAB. The proposed maintainability model can be managed efficiently and consistently, and the state of system design and maintainability can be analyzed quantitatively, thereby improving design by early identifying the items with low maintainability.