• 한국안전학회지
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• 제31권3호
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• pp.130-135
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• 2016

It is very hard to analyze the train derailment safety quantitatively at the curved section because of the diversified affect parameters including the complex interaction between wheel and rail, the train conditions such as the shape of wheel, suspension system, the track conditions such as the radius of curve, cant, transition curve, and the operation conditions, etc. Two major factors related to the running safety of railway vehicle are classified as the railway vehicle and the track condition. In this study, when the railway vehicle passing through curves of actual track condition of subway line NO.3 in seoul ($Yeonsinnae{\leftrightarrow}Gupabal$), the effect that has influence on running safety depending on rail inclination. The analysis result of 1/40 rail inclination condition is more favorable on running safety than other rail inclination conditions because derailment coefficient and wheel unloading ratio are the lowest.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마
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• pp.50-54
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• 2000

Recently, the HFPD measurement testing is widely used in partial discharge measurement of HV machines because HFPD measurement testing receives less influence of external noise and has a merit of good sensitivity. Also HFPD testing is able to offer the judgement standard of degradation level of HV machine and can detect discharge signals in live-line. Therefore it is very useful method compare to previous conventional PD testing method and effective diagnosis method in power transformer that requires live-line diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In recent, the study of partial discharge is carrying out discover of initial defect of power equipment through condition diagnosis and system development of degradation diagnosis using HFPD(High Frequency Partial Discharge) detection. In this study, simulated transformer is manufactured and HFPD occurred from transformer is measured with broad band antenna in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages.

• 한국정보과학회논문지:소프트웨어및응용
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• 제31권12호
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• pp.1581-1590
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• 2004

본 논문은 한 가지 특징 요소로서 획 방향 코드들만을 사용하는 강건한 오프라인 필기체 숫자 인식 방법을 제안한다. 이 방법은 입력된 숫자 이미지에 대하여 일반적인 8방향 코드를 생성하고 이 코드들의 조합을 다층 신경망에 학습하고 각 숫자를 인식하게 한다. 8방향 코드들은 다양하게 표현된 숫자들의 자기구성 그래프(SOG*:Improved Self-Organizing Graph) 세선화 결과에 의해 만들어지고 이 코드의 사용은 2개 이상의 특징점들을 처리하는 기존의 복합적인 단계들을 단순화시킨다. 실험결과는 모든 숫자 데이타베이스의 어떤 이미지들에 대해서도 인식률이 일관성 있게 98.85% 이상임을 보여준다.

• Journal of Computing Science and Engineering
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• 제1권2호
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• pp.125-160
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• 2007

Data Warehousing and OLAP (On-Line Analytical Processing) have turned into the key technology for comprehensive data analysis. Originally developed for the needs of decision support in business, data warehouses have proven to be an adequate solution for a variety of non-business applications and domains, such as government, research, and medicine. Analytical power of the OLAP technology comes from its underlying multidimensional data model, which allows users to see data from different perspectives. However, this model displays a number of deficiencies when applied to non-conventional scenarios and analysis tasks. This paper presents an attempt to systematically summarize various extensions of the original multidimensional data model that have been proposed by researchers and practitioners in the recent years. Presented concepts are arranged into a formal classification consisting of fact types, factual and fact-dimensional relationships, and dimension types, supplied with explanatory examples from real-world usage scenarios. Both the static elements of the model, such as types of fact and dimension hierarchy schemes, and dynamic features, such as support for advanced operators and derived elements. We also propose a semantically rich graphical notation called X-DFM that extends the popular Dimensional Fact Model by refining and modifying the set of constructs as to make it coherent with the formal model. An evaluation of our framework against a set of common modeling requirements summarizes the contribution.

• 전기학회논문지
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• 제65권2호
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• pp.354-359
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• 2016

Power plants maintenance data is to be sent to management server system via a communication network. In this case, reliable communication network is required. Transmission of the power plants maintenance data is used in the wired communication network or wireless communication network. PLC communication network is a kind of wired communication network. However PLC communication network is easily affected by noise. On the vulnerable areas in power line system, such as a mountain or rural areas, it is difficult to form a power line communication network. For a wireless communication, environment are also influenced factors in wireless communication. Harsh environmental factors are bring the communication characteristic degradation. In such areas it can be used a combination of two networks and in this way the complementary function can be achieved. Power plants are distributed in various regions across the country. The appropriate communication network is needed to maintain the power plant.This study investigated the effect of environment on the wired communication and wireless communication. It would examine a variable factor which is affect to the communication characteristic. We used PLC communication for wired communication network and ZigBee communication for wireless communication network. We investigated the characteristics of a single communication network and it raised the need for a complex communication technology to complement a single communication network.

• 천문학회보
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• 제43권2호
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• pp.45.3-46
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• 2018

Oscillations in a sunspot are easily detected through the Doppler velocity observation. Although the sunspot oscillations look erratic, the wavelet analysis show that they consist of successive wave packets which have strong power near three or five minutes. Previous studies found that 3-min oscillation at the chromosphere is a visual pattern of upward propagating acoustic waves along the magnetic field lines. Resent multi-height observations help this like vertical study, however, we also focus on horizontal facet to extend three dimensional understand of sunspot waves. So, we investigate a fragmented sunspot expected to have complex wave profiles according to the positions in the sunspot observed by the Fast Imaging Solar Spectrograph. We choose 4 points at different umbral cores as sampling positions to determine coherence of oscillations. The sets of cross-correlation with three and five minutes bandpass filters during a single wave packet reveal interesting results. Na I line show weak correlations with some lags, but Fe I and Ni I have strong correlations with no phase difference over the sunspots. It is more remarkable at Ni I line with 3-min bandpass that all sets of cross-correlation look like the autocorrelation. We can interpret this as sunspot oscillations occur spontaneously over a sunspot at photosphere but not at chromosphere. It implies a larger or deeper origin of 3-min sunspot oscillation.

• 천문학회보
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• 제44권1호
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• pp.42.3-42.3
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• 2019

The high-resolution near-infrared (NIR) spectroscopy can reveal the evidence of the accretion burst (e.g., the broadened absorption features produced by the Keplerian disk motion) although the moment of the outburst was not caught. The embedded protostar IRAS 16316-1540 observed with the Immersion Grating Infrared Spectrograph (IGRINS, $R={\Delta}{\lambda}/{\lambda}{\sim}45000$) shows the broad absorption features in atomic and CO transitions, as seen in FU Orionis objects (FUors), indicative of an outburst event. We examine whether the spectra of IRAS 16316-1540 arise from the rotating inner hot gaseous disk. Using the IGRINS spectral library, we show that the line profiles of IRAS 16316-1540 are more consistent with an M1.5 V template spectrum convolved with a disk rotation profile than the protostellar photosphere absorption features with a high stellar rotation velocity. We also note that the absorption features deviated from the expected line profile of the accretion disk model can be explained by a turbulence motion generated in the disk atmosphere. From previous observations that show the complex environment and the misaligned outflow axes in IRAS 16316-1540, we suggest that an impact of infalling clumpy envelope material against the disk induces the disk precession, causing the accretion burst from the inner disk to the protostar.

• 천문학회보
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• 제44권2호
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• pp.36.2-36.2
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• 2019

Fe II emission is a prominent and ubiquitous feature in the spectra of broad-line Active Galactic Nuclei (AGN) by producing a pseudo-continuum from UV to optical with complex and strong blends of the numerous emission lines themselves, other emission lines, and continuum. Since theoretical modeling of such intricate Fe II emission is very difficult and still far from able to reproduce observed data in detail, an empirical iron emission template, derived from observations of a narrow-line Seyfert 1 galaxy, is an essential and practical tool to obtain accurate measurements of all the emission lines and continuum in AGN spectra. However, the existing iron templates, based on the single prototypical strong Fe II emitter I Zw 1, are suffering from inadequate S/N and non-simultaneous, inconsistent data with limited wavelength coverage, which consequently limit the accuracy of all the spectral measurements. To overcome the limitations and construct an improved iron template with wide spectral coverage, high-quality UV and optical spectra for the new and better identified template galaxy, Mrk 493, were successfully obtained from our HST STIS program (GO-14744). We will show the preliminary results for multicomponent spectral decomposition of the data and template construction with application tests to various AGN spectra and comparison with previous templates.

• 한국전자통신학회논문지
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• 제19권1호
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• pp.181-188
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• 2024

정밀 설비 기술의 발전으로 4축 CNC 정밀 가공 기술의 중요성이 증대되고 있다. 그러나, 복잡한 형상 가공으로 인해 시스템 구동은 어려운 실정이다. 본 논문은 이러한 문제를 해결하기 위해 4축 제어 구조물을 제작하고, 상용 프로그램을 이용없이 Bresenham's Line Algorithm과 Runspeed Algorithm을 구현하여 정밀 제어 및 효율성을 비교하였다. Runspeed를 적용할 경우 Bresenham 대비 약 12.03%의 오차 개선과 곡률 정밀도 향상이 있었으며, 회전축 A모터를 구동하여 입체 구조물에도 정밀한 가공이 가능함을 확인하였다.

• 한국시뮬레이션학회논문지
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• 제29권1호
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• pp.57-69
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• 2020

DBR(Drum-Buffer-Rope)은 하나의 병목공정이 존재하는 생산라인을 드럼, 버퍼 그리고 로프로 구성하여 제약설비인 병목공정을 중심으로 효과적인 스케줄링을 수립하는 데 좋은 전략으로 알려져 있다. 하지만 최근 제품의 다양성이 증가되면서 공정의 복잡성이 높아지고, 자재 및 중간재의 재투입을 요구하는 공정이 많아지고 있다. 재투입 공정은 원자재가 완제품으로 생산될 때까지 동일한 설비에서 반복적으로 작업처리가 되어야 하므로 복잡한 작업환경을 가지게 된다. 본 연구는 기존의 흐름공정에서 우수한 성능을 보인 DBR 기반의 스케줄링 방법이 재투입이 있는 공정에서도 효과적으로 적용 가능한지 여부와 이를 위해서 추가적으로 검토되어야 할 전략들을 다루었다. 본 연구의 핵심은 재투입 공정에 DBR 방법을 적용하기 위하여 재투입 공정을 여러 개로 쪼개어 하나의 병목공정을 갖는 임의의 흐름공정(루프)으로 재구성한다는 점이다. 이러한 구조를 기반으로 본 연구에서는 두 가지 의사결정에 초점을 맞추어 생산 스케줄링 전략을 구성하였다. 첫째, 흐름공정마다 적정 수준의 재고수준과 안정적 생산성을 유지하기 위해 자재 투입시점과 적절한 투입량을 결정한다. 둘째는 각 공정별 상이한 작업 우선순위를 결정하는 방법이다. 본 연구는 실험을 위해 HP사의 TRC(Technology Research Center) 공정에 대한 시뮬레이션 모델을 설계하였고, DBR 기반 루프 스케줄링을 적용한 결과, cycle time의 감소 및 재공품재고의 루프 간 균형을 유지하는 것을 확인하였다.