• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1586-1589
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• 2005

GUMF (Global User Management Framework) that is proposed in this research can be applied to next generation network such as BcN (Broadband convergence Network), it is QoS guaranteed security framework for user that can solve present Internet's security vulnerability. GUMF offers anonymity for user of service and use the user's real-name or ID for management of service and it is technology that can realize secure QoS. GUMF needs management framework, UMS (User Management System), VNC (Virtual Network Controller) etc. UMS consists of root UMS in country dimension and Local UMS in each site dimension. VNC is network security equipment including VPN, QoS and security functions etc., and it achieves the QoSS (Quality of Security Service) and CLS(Communication Level Switching) functions. GUMF can offer safety in bandwidth consumption attacks such as worm propagation and DoS/DDoS, IP spoofing attack, and current most attack such as abusing of private information because it can offer the different QoS guaranteed network according to user's grades. User's grades are divided by 4 levels from Level 0 to Level 3, and user's security service level is decided according to level of the private information. Level 3 users that offer bio-information can receive secure network service that privacy is guaranteed. Therefore, GUMF that is proposed in this research can offer profit model to ISP and NSP, and can be utilized by strategy for secure u-Korea realization.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.63-67
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• 2009

The previous work (Cheong et al., 2006) where the characteristics of acoustic emissions of wind turbines has been investigated according to the methods of power regulation, has showed that the acoustic power of wind turbine using the stall control for power regulation is more correlated with the wind speed than that using the pitch control. In this paper, basically extending this work, the noise generation characteristics of large modern upwind wind turbines are experimentally indentified according to the power regulation methods. To investigate the noise generation mechanisms, the distribution of noise sources in the rotor plane is measured by using the Beam-forming measurement system (B&K 7768, 7752, WA0890) consisting of 48 microphones. The array results for the 660 kW wind turbine show that all noise is produced during the downward movement of the blades. This result show good agreement with the theoretical result using the empirical formula with the parameters: the convective amplification; trailing edge noise directivity; flow-speed dependence. This agreement implies that the trailing edge noise is dominant over the whole frequency range of the noise from the 660 kW wind turbine using the pitch control for power regulation.

• 한국통신학회논문지
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• 제27권5C호
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• pp.422-434
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• 2002

본 논문에서는 대용량 트래픽의 효율적 전송을 위해 B-DCS(Broadband-Digital Cross-connect System)망, 간선링, 지선링의 3계위 구조 광섬유 기간전송망을 제안하며 각 계위에서 경제적으로 망의 생존도를 보장하는 설계방법을 연구한다. 링 구축비용을 혼합정수계획(MIP) 모델을 이용해 수리적으로 최적화할 경우 비다항식 완전 문제(NP-complete problem)가 되어 실시간 내에 해를 구하기가 어려워지므로 본 논문에서는 B-DCS망을 위한 운용회선 및 예비회선의 최적할당 문제, 간선링을 위한 다중링 부하최적화 문제, 지선링을 위한 중첩링 부하최적화 문제에 대한 휴리스틱 알고리즘을 각각 개발하여 사례분석을 통해 그 효용성을 보인다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1320-1323
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• 2002

This paper reviews the Korean government’s selection process of core wireless communications technologies, and presents technology trends, perspectives and strategies of 5 core technologies to develop in wireless communications areas based on the mid term IT technology development plan(2002∼2004). Delphi Panel Method and Analytic Hierarchy Process(AHP) Analysis were adapted to select 30 core technologies in 9 strategic areas. Especially, 5 core wireless communications technologies out of 24 required technologies are selected: 4 G Core Technology, Broadband Wireless Access Network Technology, IMT-2000 Plus STP Technology, OBP Based Multimedia Satellite Communications Technology, Stratosphere Communications System Technology. Strategic national IT R&D program has been essential to continue success story of CDMA technology, and acquiring technology independency from advanced nations. In long term perspectives, a strategy of intensive investment with prudent selection onto core technologies should be deployed in the IT R&D programs. Also, the national IT R&D programs should be limited in the high risk & high returen areas where only government can afford the failures as well as better spill over effects are expected for the technology development and national economy. Korean industry has some strength in wireless communications technology area. Therefore, more policy concerns should be given into this area not only to secure present strength but also to explore better technology competitiveness.

• 한국음향학회지
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• 제24권6호
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• pp.303-308
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• 2005

본 연구에서는 해상 실험 자료를 사용해 저주파 광대역 음원으로서 전구 음원의 음향학적 특성을 연구하였다. 본 연구를 위해 연속 전구 신호 획득이 가능한 전구 음원을 사용하였다. 본 논문에서는 전구 음원 특성 분석 결과를 나타내었으며, 이전 연구 논문과 비교하였다 연구 결과 전구 신호는 수심이 증가함에 따라 최고 음원 준위와 주 공진 주파수가 증가하는 것을 알 수 있었다. 또한 전구 음원을 사용한 지음향 파라미터 역산 연구와 정합음원 추적 연구를 통해 전구 음원에 의해 획득된 지음향 파라미터가 수중 음원 위치 추적에서 사용 가능함을 확인하였다.

• 천문학회보
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• 제35권2호
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• pp.27.1-27.1
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• 2010

Globular cluster (GC) systems in most galaxies, particularly in ellipticals, show bimodal color distributions. Because broadband colors trace metallicity at old ages, this phenomenon has been commonly interpreted as bimodal metallicity distributions, implying the presence of two sub-populations in the globular cluster system within a galaxy. However, a new explanation has recently been proposed, in which the non-linear nature of color-metallicity relations induced by horizontal-branch stars can produce bimodal color distributions even from unimodal metallicity distributions. In this study, we put these two explanations to the test on the origin of color bimodality, using multi-band (U,B,V and I) photometry of globular clusters in NGC 1399, the central giant elliptical galaxy in Fornax galaxy cluster. We find significant changes in the morphology of color distributions when using different colors. The observation is also well reproduced by the Monte Carlo realization of GC color when a unimodal metallicity distribution and the theoretical non-linear color-metallicity relations are assumed. We discuss the implications regarding theories on galaxy formation and evolution.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.478-483
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• 2003

In this paper, in order to fabricate the circularly polarized diversity system which will mitigate multipath fading, 5.8GHz band microstrip array antenna were designed and fabricated. These antenna were designed using Ensemble 6.0 program and the fabricated antenna were vertical and horizontal polarized antenna, left-handed circularly polarized antenna, and right-handed circularly polarized antenna. The designed antenna parameters included S11 and impedance characteristics of fabricated antenna were measured using Network Analyzer(8753ES). From the measurement results, the S11 for each polarization antenna at resonance frequency of 5.8GHz band was showed -38dB, -44dB, and -50dB respectively and it was similar to the simulation result, and also the impedance can be matched at $50{\Omega}$. In order to compare polarization characteristics, broadband measurement was also conducted in this paper.

• 대한기계학회논문집B
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• 제20권2호
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• pp.710-719
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• 1996

Laser applied combustion diagnostic techniques-laser induced fluorescence (LIF) and coherent anti-Stokes Ramann spectroscopy (CARS)-are demonstrated. The profiles of hydroxyl radical (OH) and temperature in the counterflow burner are measured and compared with the numerical results. OH radical is excited on the Q$_1$(6) line of the $A^2$$\sum^+$$\leftarrow$$X^2{\prod}$(1, 0) band transition (281.1 nm) and LIF signal is measured at the the bands of (0, 0) and (1, 1) transition (306~326 nm). Absolute OH radical is obtained by using the laser absorption technique. The quenching effects are considered. Temperature is measured using broadband CARS system. Two dimensional OH radical profile is also obtained. The profiles of OH radical and temperature are found to agree well with those of numerical calculation.

• Journal of Advanced Marine Engineering and Technology
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• 제31권8호
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• pp.970-974
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• 2007

A mixer is a key component in the wireless communication systems. In this paper, we design a mixer which is used in a frequency modulated continuous wave(FMCW) radar system. The frequency sweep range of the radar is from 10 GHz to 11 GHz. The transmitted and received signals of the FMCW radar are applied to LO and RF ports of the mixer, respectively, but the frequency difference between the two signals, which is called "a beat frequency" is under a few KHz and depending on the distance to target. Thus the isolation between the LO and RF ports is very important factor to design this mixer. In this paper we propose a single balanced resistive mixer using GaAs MESFET for this application. We first design a single-ended type resistive mixer using a simulation tool, then design a balanced type to increase the LO-to-RF isolation of the mixer. We fabricated the mixer on the substrate of dielectric constant 10 and thickness 0.635 mm. The measured results show that the isolation and conversion loss of the mixer over the frequency band is 20dB and 10.5dB, respectively. The LO input power for operating the proposed mixer is +3dBm, which is lower than a general conventional mixer's LO power. The 1 dB compression point is 6dBm.

• 정보처리학회논문지C
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• 제12C권6호
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• pp.793-798
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• 2005

본 논문에서는 방송, 통신, 인터넷이 통합되는 BcN 환경에서 멀티캐스트(Multicast) 서비스를 지원하기 위한 네트워크의 분기점(Rendezvous Point)에서 시스템 모델을 살펴본다 서비스에 따른 다중의 큐와 단일 서버로 이루어진 버퍼를 기하 분포의 배치 확률을 가지는 입력이 들어올 때, 단일 큐와 단일 서버로 모델링하여 입력률 $\lambda$에 따른 버퍼의 크기를 보이고, 서비스 제공자와 네트워크 운영자 사이의 관계를 알아본다. 이때 두 관점의 이익이 같아지는 최적의 입력률 ${\lambda}_{opt}$를 기준으로 새로운 서비스 요청에 대하여 이익을 기반으로 하는 호 수락 제어를 할 수 있는 범위를 제시한다.