• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.9-14
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• 2008

Intentional city bands and public radio frequencies could reduce the internet transmission speed on the wired lines because AM and HF band are overlapping on the xDSL up and down data steam by way of the wired transmission lines. We were designed the adaptive common mode rejection circuit with 2 way amplifier against public radio frequency. Specially our circuits were applied for power and signal lines. We could reduced the common mode rejection up to 30dB and increased the up stream speed around 1.8 times using a our developed equipments. Also it could expanded the transmission distance up to 1.7 times than old lines.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.2
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• pp.63-70
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• 2017

Clinically, the fit of fixed prosthesis is an essential element for successful restoration. The fit of prosthesis is largely classified into marginal fit and internal fit, and various methods to assess these have been introduced including microscopic margin measurement, cross-sectional measurement, silicone replica technique, 3-dimensional scanning data superposition, weight technique and micro CT scanning. Thus, this study is aimed at proposing a more convenient and accurate measurement method of fits in a digital environment by comparatively analyzing the advantages and disadvantages of each known method based on existing literature.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.3
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• pp.273-281
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• 2001

The landslide occurrence in Sam-Chuck area was analyzed through Geo-Spatial Information System and AHP(Analytic Hierarchy Process). Among many factors which causes landslide, terrain slope, terrain aspect, lithology, soil texture and vegetation arc taken as input data from existing maps and constructed as a database. These factors are determined by each environmental factor by environmental and geological characters in the study area, and the rating and weight about factor are input using AHP. Possible areas for landslide have been extracted by overlaying each layers. Finally, the estimated results are compared with real landslide sites to know which factor is the most effective for landslide. The results showed that lithology and soil factor have high susceptibility in Sam-Chuck area.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.407-413
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• 2008

This paper investigates the dynamics of a HDD spindle system due to the change of FDBs. Flying height of the HDD spindle system is determined through the static analysis of the FDBs, and the stiffness and damping coefficients are calculated through the dynamic analysis of the FDBs. Free vibration characteristics and shock response of the HDD spindle system are analyzed by using the finite element method and the mode superposition method. Experimental modal test is also performed to verify the accuracy of the proposed method. This research shows that the stiffness coefficients of journal heating mostly affect the rocking frequencies because their magnitude are within the range of the stiffness of supporting structure. It also shows that the damping coefficients of thrust bearing mostly affect the axial frequency because the stiffness of thrust bearing is much smaller that that of supporting structure.

• The Korean Journal of Financial Management
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• v.11 no.2
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• pp.131-159
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• 1994

주가과잉반응(overreaction)이라 함은 투자자들이 특정 투자정보를 과대평가하여 주가에 반응하는 현상인데, 본 연구는 우리나라 주식시장에서의 주가과잉반응가설(株價過剩反應假說)(overreaction hypothesis)을 여러 가지의 대체적 방법을 사용하였으며, 따라서 우리나라 주식시장의 주가반전현상에 대하여 보다 체계적인 결론을 얻는데 목적을 두었다. 특히 위험요소를 고려하기 위하여 시장조정수익률모형, 위험조정수익률모형을 이용하였으며, 규모차이를 고려하기 위하여 자기자본총액에 따라 각각의 포트폴리오를 재구성하여 분석하였다. 그리고 초과수익률 산출시 대용되는 시장포트폴리오수익률을 종합주가수익률(KCI)과 동일가중주가지수수익률(EWI)을 이용하여 분석하였다. 본 연구의 분석기간은 1980년에서 1992년까지의 월별개별주가수익률을 이 용하였으며, 연구방법론에 있어서 국내의 기존연구에서 사용된 연구방법을 이용하였는데 이는 방법론차이로 인해 분석 결과가 상이해질 우려를 배제하고 일관성 있는 결론을 내림과 동시에 비교측면을 제고시키기 위한 배려였다. 이와 같은 여러 대체적 분석방법을 사용하여 얻은 결과에 따르면 국내외 여러 연구와는 달리 우리나라 주식시장에서의 주가과잉반응현상(株價過剩反應現象)은 투자자들이 입수한 정보에 대해 과민반응함으로써 주가가 본질적(本質的) 가치(價値)로부터 이탈되는 것이 아니고, 주로 기업규모효과(企業規模效果)(firm-size effect)와 신년효과(新年效果)(turn-of-the-year effect)등이 중첩(重疊)되어 나타나는 이례적(異例的) 현상(現象)(anomalies)으로 인한 주가반전현상(株價反轉現象) 이라고 말할 수 있겠다.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.25-31
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• 2004

This paper describes a new vibration-suppression technique for flexible cantilevered structures by using a pipe containing an internal flow. The stability and dynamic response are analyzed based on the finite element method. The flutter limit and optimum stabilizing fluid velocity are determined in root locus diagrams. The impulse responses of the system are studied by the mode superposition method to observe the damping rate of the motion. The stabilizing effect of an internal flow is demonstrated by impulse responses of the structures with and without an material damping. It is found that the response of the pipe with flow of liquid has a larger effect of, stabilizing than that with flow of gas.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8B
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• pp.609-614
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• 2008

Upstream data frame of TDM-PON includes various types of overheads, and there exist guard bands between consecutive frames from different ONUs. Although they are indispensible in synchronization and performance, they cause bandwidth waste at the same time. To solve this problem, a new TDM-PON that uses two types of wavelengths in upstream transmission is suggested. By even distribution of two wavelengths among ONUs and overhead overlap between frames that use different wavelengths, almost 100% bandwidth efficiency could be achieved. A serializer that multiplexes signals from two wavelengths is implemented for this purpose.

• Spatial Information Research
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• v.8 no.1
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• pp.31-50
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• 2000

In establishing the NGIS (The National Geographic Information System) , the Korean Government has been computerizing maps such as topographical maps as well as thematic maps. If the digital maps are mapped according to their use purpose, they can be efficiently used. The goals of this study is to describes the reasonable inspection process of digital maps. For these goals, quality controls and test processes of digital maps are investigated and then the error types of digital maps are analyzed. Nine standards which are data lineage, data format, positional accuracy, attribute accuracy, topology, logical consistency, edge-matching , completeness, outline range are established and nine steps, multi steps, which are making a work plan, analysing error types of digital maps, inspection with the naked eyes, a computerized inspection , a automatic inspection, the judge of results, the analysis of results are proposed.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.89-96
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• 2007

Finite failure NHPP models presented in the literature exhibit either constant. monotonic increasing or monotonic decreasing failure occurrence rates per fault. Accurate predictions of software release times. and estimation of the reliability and availability of a software product require quality of a critical element of the software testing process : test coverage. This model called Enhanced non-homogeneous Poission process(ENHPP). In this paper, exponential coverage and S-type model was reviewed, proposes modified(the superosition and mixture) model, which make out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method. model selection based on SSE statistics for the sake of efficient model, was employed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.29-37
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• 2005

One of the principal disadvantages of multicarrier modulation technique is the sensitivity to the frequency offset introduced by Doppler shift. This frequency offset introduces inter-carrier interference (ICI) among the multiplicity of carriers in the multicarrier modulated signal. However, Doppler spread induced by temporal channel variations can Provide another means for diversity. In this paper, we propose a modified multicarrier code division multiple access (CDMA) system to exploit Doppler diversity as well as multipath diversity. The key work of our framework is a canonical time-frequency-based decomposition of the mobile wireless channel into series of independent fading channel. The decomposition naturally leads to a time-frequency generalization of the Rake receiver that exploits both multipath and Doppler diversity.