• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6A
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• pp.920-930
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• 1999

Many researches on the multi-level QAM(Quadrature Amplitude Modulation) which is known to be a promising digital data transmission method for efficient use of channel bandwidth have been carried on, and their applications to various real fields are now being in progress. However, in the band-limited communication systems, each transmitted symbols is distorted by the ISI(Intersymbol Interference) and the phase error. Therefore, an equalizer and a carrier recovery must be taken into considerations to attenuate the effects of these distortions in the receiver. This paper presents an effective receiver structures that is applicable to the multi-level QAM. The proposed receiver system is consisted of an equalizer with Godard’s blind algorithm and a carrier recovery circuit. The phase error is estimated with a $\theta$-matching algorithm and is used in the carrier recovery to recover the correct phase. The simulation results are included to evaluate performance of the proposed receiver system for the various channel models.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.302-308
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• 2012

Self-configuration network model is to overcome the limits of data communications at sea. As a research for enhancing the connectivity and scalability of data networks at sea using the diversity and heterogeneity of the data networks on land, in this paper, a routing scheme (NLTCR) based on not conventional hop counts but distances to destination ships is introduced. The NLTCR seeks an optimal route by normalized distances to a destination, and transmission characteristics of applications and carriers. Performance is evaluated and compared with those of the max-win (MWR) and the normalized transmission characteristics (NTCR) based schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11A
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• pp.924-932
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• 2011

In this paper, we propose a possibility of usage of carrier superpositioning scheme for a specific slow frequency hopping(SFH) transmission method for the satellite data link in which all of hopping carriers have to be synchronized to DSM transponder of our previous work and usage of frequency diversity in the saved frequency to overcome the SFH disadvantage against jammer. We have analyzed anti-jamming performance and LPI performance and confirmed that the proposed scheme can support data service with 18.5dB processing gain against the worst case partial band jamming and give 2.5dB gain in the LPI performance against D&M detector which can estimate the data rate of unknown signals.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.830-837
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• 2009

In this thesis, Multi-code/Multi-carrier CDMA(MC/MC CDMA) system which is combination of Multi-code CDMA and Multi-carrier CDMA is analyzed. This system is suitable fur multi-rate services that use multi-codes and high data rate transmission that employ multi-carriers. In addition, the MC/MC CDMA system is robust against frequency selective fading, is good for narrowband interference rejection, and has higher spectral efficiency. In this paper, The users are assigned OVSF codes as a spreading code according to their data rates and divides the active users having different representative code split into a number of groups for effective cancellation. At the receiver, The code grouping interference canceller performs cancellation between the groups. The proposed receiver does not require any information about interference users, such as code, data and amplitude, and has relatively low complexity. The results show the large improvement in performance that can be attained by cancellation scheme.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.1
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• pp.45-55
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• 2018

Concerns are emerging in marine industry on the additional fatigue damages induced by hydroelasticity, and large container carriers, among others, are considered to be susceptible to this hydroelastic response due to its large size, deck openings and high speed. This study focuses on the fatigue damage estimation of 9,400TEU container carrier based on the full scale measurement data via long-base strain gage installed on the ship. Some correlation analyses have been also done to check whether there was significant torsional response during the voyage. Direct cycle counting method was used to derive stress histogram and the long-term fatigue damage was estimated based upon that analyzed data. It turned out that the fatigue damage of this particular ship during the measurement period increased by more than 60% due to the hydroelastic response of the hull, and main contribution is considered to come from vertical bending mode.

• Journal of Genetic Medicine
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• v.13 no.1
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• pp.20-25
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• 2016

Purpose: Xeroderma pigmentosum (XP) is rare autosomal recessive genetic disorder of DNA repair in which the ability to repair damage caused by ultraviolet light is deficient. We reported the first molecularly confirmed Korean patient of XP by targeted exome sequencing. The prevalence of XP included all subtype and carrier frequency of XP-A the using public data were estimated for the first time in South Korea. Materials and Methods: We described a 4-year-old Korean girl with clinical diagnosis of XP. We performed targeted exome sequencing in the patient for genetic confirmation considering disease genetic heterogeneity and for differential diagnosis. We verified a carrier frequency of c.390-1G>C in XPA gene known as mutational hot spot using Korean Reference Genome Data Base. We estimated the period prevalence of all subtypes of XP based on claims data of the Health Insurance Review and Assessment Service in South Korea. Results: We identified homozygous splicing mutation of XPA (c.390-1G>C) in the patient. The carrier frequency of risk for XPA (c.390-1G>C) was relatively high 1.608 e-03 (allele count 2/1244). The prevalence of XP in South Korea was 0.3 per million people. Conclusion: We expect that c.390-1G>C is hot spot for the mutation of XPA and possible founder variant in South Korea. However, the prevalence in South Korea was extremely low compared with Western countries and Japan.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.2
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• pp.199-204
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• 2013

Marine data communications still look for a novel data communication system at sea because of the restriction of bandwidths and costs of current carriers. In order to make the most efficient use of the broadband land carriers at sea, this paper proposes a routing scheme (MCS-NTC) at a marine MANET model. The routing scheme optimizes the route by choosing optimal nodes and carriers among the traditional and land carriers based on normalized transmission characteristics of applications and carriers. The performance is compared with the max-win method (OMH-MW) scheme considering the specific values of transmission characteristics. The result shows that our scheme derives more efficient routes than the previous one in terms of the transmission characteristics such as bandwidth, cost, delay, the number of hops and carriers.

• 한국기계연구소 소보
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• s.9
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• pp.183-191
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• 1982

This report describes the analysis method of the full-scale propulsive performance by using the data of model test and the full-scale speed trial. The model test data were analyzed by the computer program "PPTT" based on "1978 ITTC Performance Prediction Method for Single Screw Ships." Also the full-scale speed trial data were analyzed by the computer program "SSTT" based on the newly proposed “SRS-KIMM Standard Method of Speed Trial Analysis." An analysis of model and full-scale test data was carried out for a 60.000 DWT Bulk Carrier and the correlation between model and full-scale ship was stuied.

• Journal of Distribution Science
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• v.16 no.3
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• pp.69-77
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• 2018

Purpose - As more low cost carriers are introduced, the competition between the low cost carriers to become the nation's leading low cost carrier is also being intensified. The purpose of this study is to select various choice attributes for low cost carrier and figure out important factors that customers take into account for low cost carrier selection. The study also involves in establishing the relationship between perceived value, customer satisfaction, and customer behavior Intention, in an effort to identify choice attributes that are important to customers' low cost carrier. Research design, data, and methodology - To examine these research models, samples were collected from 247 peoples who visited In-Cheon international Airport during June, 2017. Results - The results of the study showed that, 'reservation service', 'airport service', 'in-flight service', and 'price' services have a significant effect on the perceived value of the choice attributes. While 'reservation service', 'airport service', 'in-flight service', and 'flight operation service' have a significant effect on the customer satisfaction of the choice attributes, perceived value has a significant effect on customer satisfaction. Perceived value has a significant effect on customer behavior intention. Finally, customer satisfaction has a significant effect on customer behavior intention. Conclusions - Flight operation service has no significant effect on perceived value of the choice attributes of low cost carriers, which indicates that the low cost carriers have not yet been well-established in the flight operation service sector. It seems likely that low cost carrier will be able to gain a competitive advantage over other companies if they expand their routes and improve the convenience of flight connections. In addition, the results show that the price service does not have a significant effect on customer satisfaction of the choice attributes of low cost carriers. From this, we may assume that the airline ticket prices of low cost carriers are already low, and the price cannot be a deciding factor in the competitive advantage of low cost carriers. To achieve higher customer satisfaction of the choice attributes, companies should strengthen the competitiveness of 'reservation service', 'airport service', 'in-flight service', and 'flight operation service'.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.271-280
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• 2020

Purpose : The purpose of this study examines the mediating effect of women leader's characteristics in the relationship between clan culture and market culture of global companies. In addition, this study attempts to analysis the mediating effect of women leader's position and carrier in the relationship among facilitator, mentor, producer, and director leadership using partial mediation and completed mediation model. Research design, data, methodology : Conceptual research model is designed with three constructs such as clan culture, woemn leader's characteristics, and market culture. Based on five hundred cases with leadership styles and organizational culture of global companies, this study examine the mediating effect of women leader's characteristics in the relationship between clan culture and market culture using structured equation modeling. Results : Facilitator leadership have a significantly positive influence on women leader's position and carrier. Mentor leadership have a significantly positive influence on women leader's carrier while they are not correlated with mentor leadership and women leader's position. Women leader's position and carrier have a significantly positive influence on director leadership while women leader's position and carrier not have a positive influence on procucer leadership. Also facilitator and mentor leadership have a significantly positive on producer and director leadership. Conclusions : By controlling for the mediating effect of women leader's characteristics, this study have improved the academic contributions as well as policy and practical implications through empirical study of clan culture that affect market culture in the filds of leadership style and organizational. In addition, this study means that the mediating effects on the variables of women leader's position and carrier were examined.