• Journal of Korea Multimedia Society
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• v.10 no.7
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• pp.902-911
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• 2007

GSM platform is a hugely successful wireless technology and an unprecedented story of global achievement. In less than ten years since the first GSM network was commercially launched, it became the world's leading and fastest growing mobile standard, using over 1 billion GSM subscribers across more than 200 countries of the world. GSM platform evolved into 3th generation mobile communication which includes not only voice call services but also the international roaming and various kinds of the multimedia services. GSM is an essential element techniques a safe data transmission and a personal private protection while support services. However, a crypto algorithm and a secure protocol for a safe data communication using GSM are indicating various kinds of problems. In this paper, we propose a more safer and more efficient authentication protocol in 3th generation network through analysis of GSM security mechanism of 2th/2.5th generation. This security protocol offers enforced security efficiency by using user verification between SIM/ME and reduction of authentication and key agreement step between SIM/ME/AuC.

• Journal of Advanced Navigation Technology
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• v.12 no.2
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• pp.139-145
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• 2008

There has been lots of studies on communication systems using millimeter wave recently in many countries, specially in newly assigned 57GHz ~ 64GHz ISM band. Among those studies, IEEE 802.15.3c standard proposes OFDM (Orthogonal Frequency Division Multiplexing) systems for high data rate transmission support. But OFDM method has the PAPR (peak-to-Average Power Radio) problem The PAPR problem is to decline the performance of the transmission system due to signals distorted severely when passing through nonlinear components such as ADC/DAC and power amplifiers. In order to solve the problem of P APR, this paper suggests SSC (Sine Soft Clipping) and analyzes the PAPR, CCDF, PSD, BER by applying SAW(Surface Acoustic Wave) filter and power amplifiers to IEEE 802.15.3.c OFDM WPAN systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11B
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• pp.891-899
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• 2004

Ethernet passive optical network (EPON) has drawn many attention as a promising access network technology because it can provide a high bandwidth with a low cost. Since the uplink in the EPON system is shared by many users, it is necessary for an EPON system to have an efficient bandwidth allocation mechanism. In addition, as the users demand more QoS-oriented applications, it is necessary for an EPON system to have an efficient mechanism supporting QoS. In this paper, we propose a variable window dynamic bandwidth allocation (DBA) algorithm for the EPON system. Unlike the previously proposed DBA algorithms, the variable window algorithm guarantees the QoS for the highest priority class, and at the same time provides more enhanced QoS for the lower priority classes by dynamically allocating bandwidth if necessary. It is verified through the simulations that the variable window algorithm can provide more enhanced QoS performance than other DBA algorithms.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.4
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• pp.369-375
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• 2010

The study on the characteristics of nitrous oxide catalytic decomposition was carried out to utilize the nitrous oxide as a propellant. The Pt, Ir and Ru were synthesized to select a high performance catalyst for the nitrous oxide decomposition reaction. The respective catalyst precursors were loaded in the $Al_2O_3$ support using an wet impregnation method. The $N_2O$ conversion as a variation of space velocity and reaction temperature was measured using a tubular reactor. The catalyst loss was measured to evaluate the durability of catalysts after the reaction at $800^{\circ}C$ for 2 hours. The $N_2O$ conversion was increased at the decrease of space velocity and at the increase of temperature. The Ru/$Al_2O_3$ catalyst had the highest $N_2O$ conversion at low temperature and the best durability.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1429-1435
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• 2020

Applying an accurate parametric prediction model to identify abnormal or false pressurizer water levels (PWLs) is critical to the safe operation of marine pressurized water reactors (PWRs). Recently, deep-learning-based models have proved to be a powerful feature extractor to perform high-accuracy prediction. However, the effectiveness of models still suffers from two issues in PWL prediction: the correlations shifting over time between PWL and other feature parameters, and the example imbalance between fluctuation examples (minority) and stable examples (majority). To address these problems, we propose a cost-sensitive mechanism to facilitate the model to learn the feature representation of later examples and fluctuation examples. By weighting the standard mean square error loss with a cost-sensitive factor, we develop a Cost-Sensitive Long Short-Term Memory (CSLSTM) model to predict the PWL of PWRs. The overall performance of the CSLSTM is assessed by a variety of evaluation metrics with the experimental data collected from a marine PWR simulator. The comparisons with the Long Short-Term Memory (LSTM) model and the Support Vector Regression (SVR) model demonstrate the effectiveness of the CSLSTM.

• Research in Community and Public Health Nursing
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• v.8 no.1
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• pp.45-60
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• 1997

Essential hypertension is a typical chronic disease requiring adequate and continuous management. Many studies supported that self-care was the essential factor to promote the wellbeing of hypertensives and self-efficacy increased healthy, behavior. The comprehensive self-regulation program was conducted as a nursing intervention on the promotion self-care performance for hypertensives in company. And this self-regulation program was recommended to apply for hypertensives in rural area. The purpose of this study is to identify the general characteristics affecting self-care and interrelationship among the factors including self-care, self-efficacy, HLOC, perceived benefits, barriers and family support. 40 subjects were interviewed from Dec. 1996 to Jan. 1997 and the data was analyzed by the SPSS PC+ program with t-test and multiple correlation to determine the variables affecting the self-care behavior. The results were as follows: 1) Level of self-care was significant difference according to sex(t= -2.27, p=.0l9). religion (t=1.57, p=.055) and smoking habit (t=4.42, P=.000). Perceived self-efficacy was more significantly high among the non-smoking group (t=3.25, P=.000) and female group (t=-2.534, p=.0l3). 2) There were significant positive correlation among the variables: self-care and self-efficacy (r=.5460, p=.000), external-LOC and self-care(r=.2548, p=.056), external-LOC and self-efficacy(r =. 2901, p=.035), self-efficacy and perceived benefits (r=3307, p=.019). And there were significant negative correlation between self-care and barriers (r=-.5438, p=. 000), self-efficacy and barriers (r= - .4153, p=.004). From the above results, it can be concluded that the self-care is more required in male hypertensives and self-efficacy is one of the important factors to increase healthy behavior in cluding self-care. Thus self-regulation program can be recommended in the management of the hypertensives in community settings.

• Journal of Navigation and Port Research
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• v.38 no.2
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• pp.141-146
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• 2014

NIR(New Inspection Regime, hereinafter NIR) relating to the PSC(Port State Contorl, hereinafter PSC) has implemented in Asia-Pacific region under Tokyo-MOU from last January 2014. The most noticable difference between NIR and existing TF(Target Factor, hereinafter TF) is to evaluate company performance and to conduct PSC with flexible inspection interval on the basis of Ship Risk Profile; High Risk Ship, Standard Risk Ship and Low Risk Ship. Particularly deficiencies related to ISM Code, more than 5 deficiencies and detention record have a serious effect on the evaluation of Ship Risk Profile. Therefore ship and company are requested to ensure proper implementation of Safety Management System for the changed PSC tendency. Also RO(Recognized Organization, hereinafter RO) and Administration respectively should take suitable actions different to previous measures, such as implementation of cooperation and support system between vessel and company, changing subject and object for avoiding Mannerism in SMS audit, strengthening supervision on RO by Administration and establishment of private-public Partnership network.

• The KIPS Transactions:PartA
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• v.9A no.3
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• pp.317-326
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• 2002

The mobile telecommunication system has been growing exponentially after 1990s due to the high population in a city and the growth of mobile user. In this time, the current mobile system mainly concentrates on the voice communication. However, in the next generation, mobile users want to get very diverse services via mobile terminal such as the Internet access, web access, multimedia communication, and etc. For this reason, the next generation system, such as the UMTS system, has to support the packet data service and it will play the major role in the system. In different from the voice service, the packet data service should store packet data in a buffer at base station before it forwards. Consequently, the performance closely related to the buffer management and its operation. However, until now, there are rare study on the buffer behavior and management. In this paper, we will observe the buffer behavior in the UMTS systems by using simulation and analyze the results. For this research, we generate packet data traffics and model the UMTS system for a simulation. Then we analyze the buffer state by a simulation and calculate the buffer overflow probability by mathematical methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.377-386
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• 2008

In this paper, a new handover management scheme has been proposed to reduce handover latency and to support fast handover without packet losses, so that it may be applicable to the wireless mobile Internet system such as IPv6-based WiBro system. To minimize the handover latency in processing of movement detection, we propose the handover management scheme which simplifies the handover message exchanging procedure between mobile subscriber station (MSS) and network by integrating layer 2 and layer 3 handovers efficiently based on the layer2 information. To reduce the processing delay from new care-of-address (NCoA) configuration during handover, we propose that NCoA is created, distributed and managed by new access control router (NACR). In addition, in order to minimize the packet transmission delay and eliminate the packet losses, the proposed scheme employs a crossover router (CR) which is upper network located over PACR and NACR and employs the packet buffering for MSS. The simulation study shows that the proposed scheme achieves loss-free packet delivery and low latency in the environment of narrow overlapped cell area or high velocity of the MSS, comparing the performance with the conventional schemes.

• Journal of Korean Public Health Nursing
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• v.12 no.2
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• pp.107-121
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• 1998

The purpose of this study was to test the revised Health Promotion Model of Pender and to determine the factors to promote health behavior for adolescents' smoking behavior. The subjects of the study was 783 boys of 4 high school students. among 39. schools locating in Daejeon metropolitan city. The data was collected from July 1st to 15th. 1997 by school health nurse The research tool were HPLP of Walker. Pender. General self-efficacy scale of Sherer. control scale was measured by subconcept of hardiness scale of Pollock. and perceived barrier. perceived benefit. activity-related-affect tool were made by researcher via literature review The data were analyzed by SAS program using frequency. t-test. ANOVA. Schefee test. regression. The results were as follows 1. The mean of total health promoting behavior was $2.27\pm.35$. Among sub domain of health promoting behavior, the highest score was interpersonal support$(2.72\pm.60)$. and the lowest was health responsibility $(1.58\pm.44)$. 2. There were statistically significant difference in total health promoting behavior according to religion. parenting style. school performance. girl friend. father's smoking of individual characteristics. 3. The socioeconomic status. smoking, parent pattern. family structure of individual characteristics and experience domain associated with perceived benefit. perceived barrier. activity-related affect. interpersonal influence of behavior-specific cognition and affect domain. The perceived barrier. self-efficacy. girl friend and father's smoking of interpersonal influence. and control explained $25.8\%$ of variance of health promoting behavior. From above results school health nurse has to emphasize on health responsibility for health promotion of adolescent. But they couldn't intervene for parent pattern. socioeconomic status. family structure of individual characteristics and experience domain. it could be possible for school health nurse to promote health of adolescents through improving perceived barrier. also develop program to increase self-efficacy and through parent health class for fathers. Above results point to the importance of including parents in smoking prevention effort targeting adolescents. Because increasing control also promotes health of adolescents. it should be studied further about the specific measure. To verify the variables for increasing the fitness of health promoting model. it needs further replication of the research.