• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.951-957
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• 2003

The analysis of RF performance requirement conditions on communication system is critical indicator to predict the performance of system. UWB(Ultra Wide Band) system which the standard is not established yet is difficult to derive the precise system performance requirement condition. Also, there are differences between conventional UWB system and multi-band system about RF performance requirement condition. In this thesis, the differences are analyzed and performance requirement conditions of multi-band UWB system are described on the basis of the differences. Throughput, maximum transmit power, and sensitivity of multi-band UWB system is varied with respect to the number of Sub-Bands. In addition, because of Multi-path effect, if PRF(Pulse Repetition Frequency) is changed, the Multi-path link margin is happened to compensate for Multi-path Energy Loss which is contributed by increasing of the Link Margin. According to Multi-path Margin, the variation of the resistance with respect to sensitivity and interference signal is observed and analyzed through the simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.577-580
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• 2005

This paper reports the high sensitivity actuator for flexible disk. The air stabilized flexible optical disk has very small axial runout. Therefore, It is proper to develop an actuator which has high sensitivity in tracking direction rather than in focusing direction. In order to maximize driving force in radial direction, we present an efficient design of magnetic circuit with simple multi-polarized magnets and auxiliary magnets. Designed magnetic circuit has big force in tracking direction. And we shift 2$^{nd}$ resonance frequency of moving parts Into high frequency band, not causing increase of mass and discord between force and mass centers to secure high sensitivities and sufficient control bandwidth. Finally, experimental results show that designed actuator has superior sensitivity in tracking direction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.512-514
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• 2008

In this paper, a new electromagnetic circuit is proposed for an optical pickup actuator with high sensitivity. Contrary to those of conventional actuators, the proposed circuit has two focusing coils which are diagonally placed at the front and rear of a moving part. The configuration which makes the effective length of the focusing coil longer and the moving part lighter, is helpful in increasing the sensitivity of the actuator. However, the asymmetry of the moving part by two focusing coils causes flexible node vibrations in quite low frequency range. This paper shows that the design modification of the moving part for the reconfiguration of mass moment of inertia can reduce the mode vibrations.

• Journal of Aerospace System Engineering
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• v.16 no.2
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• pp.39-48
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• 2022

The purpose of this paper was to study how to improve the occurrence of abnormal altitude values of radio altimeter, due to RF interference signals during the flight of aircraft. In flight missions, since it performs a roll-out after several high maneuvers, accurate altitude must be displayed to effectively perform flight missions. Thus, a root cause analysis and trouble shooting were performed for the display of abnormal altitude values of radar altimeters, and a method of reducing RF interference signals by installing an attenuator was examined. Additionally, the verification results for the improvements are also described.

• Journal of Global Scholars of Marketing Science
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• v.6
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• pp.93-110
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• 2000

본 연구에서는 지방 중소형 백화점이 왜 서울의 대형백화점과의 경쟁에서 뒤질 수밖에 없는지를 규명하고자 노력하였다. 특히, 유통시장개방 이후, 곧바로 닥친 환란 등의 여파로 지방의 중소형 백화점들이 우후죽순 거의 몰락의 수순을 거쳤다. 따라서, 늦은 감은 있지 만, 현재 지방의 중소형 백화점이 왜 몰락의 길을 걷게 되었는지 규명하는 노력이 필요하 기 때문에 이를 위한 분석을 하였다. 본고는 이중에서 피상적으로 나타나지 않은 매우 중요한 문제, 즉, 중간관리의 존재에 대하여 논하고자 하였다. 먼저, 중간관리의 문제점을 도출하면, 거래처의 수도권 집중현상, 마진률저하의 문제, 이 노베이션 동기유발 저해환경, 채산성악화로 인한 경영악화 심화 등의 문제를 들 수 있겠다. 이를 통하여 대응방안을 모색하면 다음과 같다. 첫째, 매입형태를 특정매입에서 상품특성 에 맞는 직매입등으로의 전환이 필요하다 둘째, 지방의 중소형 백화점은 대형백화점과 영 업시스템이나 상품가격, 품목이 비슷하다. 그렇다면 상품의 구색이나, 특성을 강는 자사(PB) 상품 개발 촉진이 필요하다. 셋째, 중소형 백화점에 대한 인식을 새롭게 하고 자금 및 정책 지원의 확대가 필요하다 넷째, 조직화 협업화 협동화가 필요하다. 다섯째, 지방의 유망 브랜드를 개발하고, 육성하는 노력, 즉, 지방 산업 육성책이 필요하다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1086-1090
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• 2011

This paper presents a method to evaluate generation rescheduling priority using transient energy margin sensitivity for power system operation. A change in any of the functional parameters obviously causes a change in the energy margin. Especially the energy margin sensitivity is evaluated for change with respect to generation. For a given contingency, the energy margin is computed and the respective sensitivities are also computed. It is possible to rank the sensitivities and thereby determine the generators which will affect the energy margin most and hence affect the stability (instability) of the system. The sign of the sensitivity indicates the direction of change in generation for a given change in energy margin.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.159-170
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• 1998

Man-made noise in PCS frequency range are measured using the three axis antennal with common port and the measured data are statistically treated for modeling. The can optimal parameters of the measured APD curves can be calculated fast by using the Composite Approximation Algorithm. The calculated APD parameters can reduce the EM-environments Data Base memory and also be applied to determine the output and sensitivity margin of the transmitter and the receiver.

• Radiation Oncology Journal
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• v.20 no.1
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• pp.41-52
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• 2002

Purpose : 3D conformal radiotherapy, the optimum dose delivered to the tumor and provided the risk of normal tissue unless marginal miss, was restricted by organ motion. For tumors in the thorax and abdomen, the planning target volume (PTV) is decided including the margin for movement of tumor volumes during treatment due to patients breathing. We designed the respiratory gating radiotherapy device (RGRD) for using during CT simulation, dose planning and beam delivery at identical breathing period conditions. Using RGRD, reducing the treatment margin for organ (thorax or abdomen) motion due to breathing and improve dose distribution for 3D conformal radiotherapy. Materials and Methods : The internal organ motion data for lung cancer patients were obtained by examining the diaphragm in the supine position to find the position dependency. We made a respiratory gating radiotherapy device (RGRD) that is composed of a strip band, drug sensor, micro switch, and a connected on-off switch in a LINAC control box. During same breathing period by RGRD, spiral CT scan, virtual simulation, and 3D dose planing for lung cancer patients were peformed, without an extended PTV margin for free breathing, and then the dose was delivered at the same positions. We calculated effective volumes and normal tissue complication probabilities (NTCP) using dose volume histograms for normal lung, and analyzed changes in doses associated with selected NTCP levels and tumor control probabilities (TCP) at these new dose levels. The effects of 3D conformal radiotherapy by RGRD were evaluated with DVH (Dose Volume Histogram), TCP, NTCP and dose statistics. Results : The average movement of a diaphragm was 1.5 cm in the supine position when patients breathed freely. Depending on the location of the tumor, the magnitude of the PTV margin needs to be extended from 1 cm to 3 cm, which can greatly increase normal tissue irradiation, and hence, results in increase of the normal tissue complications probabiliy. Simple and precise RGRD is very easy to setup on patients and is sensitive to length variation (+2 mm), it also delivers on-off information to patients and the LINAC machine. We evaluated the treatment plans of patients who had received conformal partial organ lung irradiation for the treatment of thorax malignancies. Using RGRD, the PTV margin by free breathing can be reduced about 2 cm for moving organs by breathing. TCP values are almost the same values $(4\~5\%\;increased)$ for lung cancer regardless of increasing the PTV margin to 2.0 cm but NTCP values are rapidly increased $(50\~70\%\;increased)$ for upon extending PTV margins by 2.0 cm. Conclusion : Internal organ motion due to breathing can be reduced effectively using our simple RGRD. This method can be used in clinical treatments to reduce organ motion induced margin, thereby reducing normal tissue irradiation. Using treatment planning software, the dose to normal tissues was analyzed by comparing dose statistics with and without RGRD. Potential benefits of radiotherapy derived from reduction or elimination of planning target volume (PTV) margins associated with patient breathing through the evaluation of the lung cancer patients treated with 3D conformal radiotherapy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.541-541
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• 2008

반도체 소자가 차세대 초미세 공정 기술 도입의 가속화를 통해 고속화 및 고집적화 되어 감에 따라 나노(Nano) 크기의 회로 선폭 미세화를 극복하고자 최적의 CMP (Chemical Mechanical Polishing) 공정이 요구되어지고 있다. 이처럼 CMP 공정이 반도체 제조 공정에 적용됨으로써 공정 마진 확보에 진일보 하였으나 CMP 장비의 공정 조건, 슬러리의 종류, 연마패드의 종류 등에 의해 CMP 성능이 결정된다. 특히 슬러리는 연마 공정의 성능에 중요한 영향을 미치는 요인이다. 고가의 슬러리가 차지하는 비중이 40% 이상을 넘고 있어 슬러리 원액의 소모량을 줄이기 위한 연구들이 현재 활발히 진행되고 있다. 본 연구에서는 새로운 연마제의 특성을 알아보기 위해 탈이온수(De-ionized water; DIW) 에 $CeO_2$, 연마제를 첨가한 후 분산시간에 따른 연마 특성과 AFM, EDX, XRD, TEM분석을 통해 그 가능성을 알아보았다.

• The Research Journal of the Costume Culture
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• v.29 no.5
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• pp.617-633
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• 2021

The purpose of this study is to examine emerging trends in fashion films and the impact of COVID-19 through analysis of Prada films produced before and after the initial spread of the COVID-19 pandemic. We selected 40 cases occurring prior to the pandemic, from June to December 2019, and 21 cases occurring since the outbreak, from June to December 2020. To identify relevant trends, we conduct a literature review and examine a range of case studies. First, travel restrictions and confronting activities currently inhibit production. Through our case study analysis, we identify nineteen cases in between before and after COVID-19. Secondly, Prada can be seen to mainly produce episodes and promotional films. Additionally, it develops content showcasing brand values in environmental, cultural, creative, and sport-related fields; intended audiences extend beyond the realm of fashion. Thirdly, a new film category began to develop after the outbreak of COVID-19, namely, narrative films utilizing virtual interactions. According to our analysis results, we expect film production that is increasingly facilitated by virtual communication, technology utilization, and online platforms to continue even after the resolution of COVID-19. New film categories will emerge, and we predict that the gap between the number of cases before and after COVID-19 will narrow.