• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.341-348
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• 2009

Various types of micro cone penetrometers have been developed by using strain gages for the layered soil detection. Strain gages, however, are affected by several factors such as temperature, self heating and lead wire length. In this study, micro cone penetrometers with 3~7mm in diameter, are developed by using FBG sensor to overcome the defects of the strain gage, and compensate the effect of temperature during penetration. In order to verifiy the accuracy and reliability of the developed FBG cone, the cone penetration test is performed on the layered soil. The tip resistance of FBG snesor shows excellent sensitivity, and can detect the interface of the layered soils with higher resolution. In addition, the 3mm micro cone penetrometer which is impossible cone diameter by using strain gages presents much higher sensitivity than the 7mm cone penetrometer. This study suggests that FBG sensor is a useful sensor for manufaturing the ultra small sized cone, and effectively detects the interface of the layered soil.

• Journal of Families and Better Life
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• v.32 no.5
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• pp.207-219
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• 2014

The purpose of this study was to examine the characteristics of suicide attempts and non-attempts of the elderly living alone and the subjects in this study were 690 elderly persons living alone in Seoul and Gyeonggi Province. For data analysis, this study used descriptive analysis, mean comparison correlation analysis, and binominal logistic regression analysis using PASW 20.0. To explain the suicide attempts of elderly persons who live alone, variables such as sex, age education level, monthly household income, religion, subjective economic status, subjective health status, ADL/IADL, depression, hopelessness, social support, and stress were used. The findings of the study were as follows: First, 9.2 percent(64) of the elderly living alone had attempted suicide and 90.8 percent(626) had never attempted suicide. Second, monthly household income, hopelessness, and social support were identified as the factors that affected their suicide attempts. In other words, the elderly living alone who had lower monthly household income, less social support, and greater feelings of hoprlessness had made more suicide attempts. As it is a cross-sectional research using data from non-probability sampling, this has a limitation in generality sampling, this has a limitation in generalizing the study results. To overcome this limitation, longitudinal research using data from probability sampling is necessary.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1817-1823
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• 1998

V.42bis, a type of LZW(Lempel-Ziv-Welch) code, is well-known as theinter national standard is asynchronous data compression. In this paper, we analyze several undesirable phenomena arising from the application of v.42bis to high speed data transmission, and we propose a modified technique to overcome them. the proposed technique determines the proper size of the dictionary, one of important factors affecting the compression ratio, and improves the method of dictionary generation for a higher compression ratio. Furthermore, we analyze the problem of excessive mode changes and solve it to a certain degree by adjusting the threshold for mode change. By doing this, we can achieve smiller variation of the compression ratio in time. This improvement chtributes to easier and better design and control of the buffer in high speed data transmission.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.515-518
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• 1998

This paper proposes a new hybrid algorithm for auto-tuning fuzzy controllers improving the performance. The presented algorithm estimates automatically the optimal values of membership functions, fuzzy rules, and scaling factors for fuzzy controllers, using a genetic-MGM algorithm. The object of the proposed algorithm is to promote search efficiency by a genetic and modified gradient optimization techniques. The proposed genetic and MGM algorithm is based on both the standard genetic algorithm and a gradient method. If a maximum point don't be changed around an optimal value at the end of performance during given generation, the genetic-MGM algorithm searches for an optimal value using the initial value which has maximum point by converting the genetic algorithms into the MGM(Modified Gradient Method) algorithms that reduced the number of variables. Using this algorithm is not only that the computing time is faster than genetic algorithm as reducing the number of variables, but also that can overcome the disadvantage of genetic algorithms. Simulation results verify the validity of the presented method.

• Journal of Korea Port Economic Association
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• v.17 no.1
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• pp.3-26
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• 2001

Competitive and reliable maritime transport services benefit the economy as a whole, and are key efficiency factors for the production of both goods and services. Although maritime transport sector is very liberalized compared to many other service sectors, certain obstacles must be overcome before full liberalization of the maritime transport can be realized. Particularly, maritime transport services in Northeast Asia are regulated by a complicated and outdated system. To remove these barkers two approaches can be used: a regional trading arrangement approach and a multilateral approach via WTO. However, multilateral efforts are not likely to be successful in achieving any concrete progress towards maritime transport liberalization in the short- to medium-term in Northeast Asia. Consequently, it may be the best to take the following two progressive approaches and to make them work towards liberalization of the maritime transport market: a bilateral approach and a trilateral approach. A gradual process of liberalization would expand the market, help operators achieve economies of scale, promote the international division of labor and specialization, enhance the effective management of shipping services, and promote the long-term interests and welfare of the user by improving service quality and diversifying services. A liberalized and integrated maritime transport market in Northeast Asia should achieve both of these long-run policy objectives by benefiting both the transport service users and the transport service providers. In order to move the maritime transport liberalization programs as quickly as possible, it is desirable to establish a "Regional Maritime Transport Liberalization Committee." We suggest it to be a Tripartite (China, Japan and Korea) Committee initially, which can later expand its membership to include other Northeast Asian countries.

• Korean System Dynamics Review
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• v.4 no.1
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• pp.69-91
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• 2003

Using qualitative methods hinged on urban dynamics models, the paper addresses major issues concerned with new administrative capital construction. It tries to summarize the existing debates on new administrative capital construction and reinterpret diverse interacting factors in terms of reinforcing or balancing feedback structure. The paper suggests that understanding up on the dynamic mechanism imbedded in circular causal loop diagrams is the key to set up appropriate proposals and action plans for the new administrative capital, as they would reveal complicated linkages between the Capital Region and the rest, in addition to the urban dynamic of new administrative capital. In the same context, the paper can confirm similar features reflected in the relocation of capital functions at Canberra, Australia and Berlin, Germany. It has paid special attention to the fact that both Australian and German governments altogether stress the positive feedback loops as they have overcome unprecedented political confrontation among rival cities: Basically, they have encouraged gives-and-takes among major stake-holders. These research findings indicate that the future of new administrative capital construction depends on consensus buildings that can accommodate socio-economic and territorial changes between pros and cons. Although further researches and validations are needed, the system approach presented in this paper could assist Korean decision-makers in developing robust and responsive policy initiatives under uncertainties.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1878-1885
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• 2009

The railway advance policy from Korea government, KORAIL have to reduce a half of his railway business loss until 2010 and turnout railway business black ink until 2012. To overcome this difficult management situation, KORAIL has been set up new marketing organization in Seoul station which is necessary and venerable. According to the leadership of Seoul station master, Seoul station's marketing team was launched at April 2008. The marketing team will introduce total marketing for KORAIL corporation in their marketing activity such as advertisement, B to B railway tickets, railway travel package sales and customer satisfaction event with other corporations, and so on. After automated ticket system(SMS and Home-printed ticket) will lead to existing ticket sales persons to become activating marketing team members. In the organization case study in Seoul station, this study how to manage new marketing team have a great performance last 8 months and analysed what was a successful factors and principals, and also their team limits within KORAIL's organization structure. In the long run, we suggest that how can be this team to be support within KORAIL system such as incentive system, payment system, and marketing budgets etc.

• Journal of Digital Contents Society
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• v.8 no.1
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• pp.9-15
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• 2007

Smoothing is a transmission plan where variable rate video data is converted to a constant bit rate stream. Among them are CBA, MCBA, MVBA, e-PCRTT and others. e-PCRTT algorithm, which was improved from PCRTT, restricts the number of rate changes with fixed-size run. This causes unnecessary rate changes when run size is small and buffer size is large. In this paper, to overcome a shortcoming of e-PCRTT algorithm, a smoothing algorithm is proposed, which is improved from e-PCRTT, where a transmission rate transmits more intervalsl as possible. Experiments demonstrated that the proposed algorithm outperformed e-PCRTT algorithm. In order to show the performance, various evaluation factors were used such as the number of transmission rate changes, peak rate, transmission rate variability and so on.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.459-465
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• 2014

Visible light communications (VLC) using the intensity modulation of light-emitting diodes (LEDs) provides a new communication medium to overcome the shortage of radio spectrum, and allows reuse of LED lighting infrastructures. Orthogonal frequency-division multiplexing (OFDM) was introduced to VLC for its merits in mitigating the fading effects resulting from delay spread, and in avoiding low-frequency ambient interference. Noise and clipping are two major factors that degrade the performance of OFDM in VLC. A larger signal easily overcomes noise, but experiences impairment by clipping. Therefore, degradation due to clipping has a trade-off relationship with that due to noise, depending on the signal amplitude of OFDM. In this paper, the optimal signal amplitude in the trade-off is obtained by simulation when the dimming and LED intensity are given. The former indicates a user's requirement for lighting, and the latter represents the channel quality. The required LED intensity-to-noise ratio, as the channel quality that guarantees dimming as well as an adequate bit-error rate (BER), is also discussed.

• Current Optics and Photonics
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• v.1 no.4
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• pp.402-411
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• 2017

Combined LIBS-Raman spectroscopy has been widely studied, due to its complementary capabilities as an elemental analyzer that can acquire signals of atoms, ions, and molecules. In this study, the classification of polymorphs was performed by laser-induced breakdown spectroscopy (LIBS) to overcome the limitation in molecular analysis; the results were verified by Raman spectroscopy. LIBS signals of the $CaCO_3$ polymorphs calcite and aragonite, and $CaSO_4{\cdot}2H_2O$ (gypsum) and $CaSO_4$ (anhydrite), were acquired using a Nd:YAG laser (532 nm, 6 ns). While the molecular study was performed using Raman spectroscopy, LIBS could also provide sufficient key data for classifying samples containing different molecular densities and structures, using the peculiar signal ratio of $5s{\rightarrow}4p$ for the orbital transition of two polymorphs that contain Ca. The basic principle was analyzed by electronic motion in plasma and electronic transition in atoms or ions. The key factors for the classification of polymorphs were the different electron quantities in the unit-cell volume of each sample, and the selection rule in electric-dipole transitions. The present work has extended the capabilities of LIBS in molecular analysis, as well as in atomic and ionic analysis.