로드 밸런싱 Active-Active 방식의 웹 서버 이중화 구축 및 결함내성 시험

최재원,Choi, Jae-Won 한국정보통신학회 2014 한국정보통신학회논문지 Vol.18 No.1

본 논문에서는 Active-Active 방식의 웹서버 이중화 방법에 관해 연구하였다. Rsync과 crontab을 이용하여 웹서버간에 주기적인 복사가 이루어지도록 하여 동일한 상태를 유지시켰다. 로드밸런싱서버가 웹서버를 교대로 실행하여 부하를 분산하고, 빠른 서비스가 제공되도록 하였다. 또한 임의의 웹서버에 장애가 발생하더라도 또 다른 웹서버에 의해 서비스가 계속 유지되도록 하였다. In this paper we researched on the Duplication Techniques for Active-Active Web Servers. Rsync and crontab utilities make copy periodically between web servers and maintain the same status. Load Balancing Server makes web servers load balanced and fast servicing by executing web servers alternatively. Even though one web server stops due to some critical errors, the remaining web server can take over and provide services continuously.

편광현미경을 이용한 PTT/PTN 블렌드의 등온결정화 거동 분석

최재원,차희철,김영호,Choi, Jae-Won,Cha, Hee-Cheol,Kim, Young-Ho 한국섬유공학회 2005 한국섬유공학회지 Vol.42 No.6

Isothermal crystallization behaviors of poly(trimethylene terephthalate) (PTT), poly(trimethylene naphthalate) (PTN), and PTT/PTN blends were analyzed using a polarizing microscope equipped with a hot-stage. As the melting time at $260^{\circ}C$ of PTT/PTN blends increased, the crystallization proceeded slowly due to the copolymer formation which resulted from the ester interchange reaction at the elevated temperature. PTT and m-rich blends formed spherulites over the temperature range of experiment, but PTN formed spherulites only at lower crystallization temperatures such as $150^{\circ}C$. PTN and PTN-rich blends formed distorted spherulites at high temperatures such as $180^{\circ}C$, which seemed to result from the $\beta-crystal$ formation of PTN at that temperature. The radial growth rate of the spherulite formed during the crystallization was obtained by the measurement of radii of the spherulites. The radial growth rate decreased as PTN content in the blends increased.

PNF 패턴에서 회전요소에 관한 고찰

최재원,김미현,정현애,Choi, Jae-won,Kim, Mi-hyun,Jeong, Hyun-ae 대한고유수용성신경근촉진법학회 2003 PNF and Movement Vol.1 No.1

Objectives: The main purpose of this study is to analyze the importance of the rotatory factor in PNF pattern. In this article has to analyze and clarify the importance of the rotatory factor in PNF pattern by comparing the general concepts, facilitation technics, and neuroscience of muscle spindle, etc. Methods: This is a literature study with books. Results : There is close relationships between the pattern in PNF and rotatory factor. PNF pattern is priorily made up the diagonal and spiral pattern. the rotatory factor influences and guides from the start to end in the pattern. Conclusions : Rotation component is most important of the three component that one flexion or extension, abduction or adduction and rotation. It is that provide longer muscle length and stimulate the muscle spindles.

Binary CDMA 기반의 무선 VoIP 시스템의 개발방법 및 설계

최재원,Choi, Jae-Won 한국정보통신학회 2011 한국정보통신학회논문지 Vol.15 No.10

Binary CDMA는 음성 영상 등의 멀티미디어 데이터를 초고속으로 우수한 전송품질로 통신할 수 있는 우리 나라가 개발한 새로운 표준 무선통신 기술이다. 본 논문에서는 전화선의 설치나 매설 작업 없이 원하는 장소에 자유롭게 설치할 수 있는 Binary CDMA 기반의 무선 VoIP 시스템 개발을 위한 개발방법 및 설계에 관해 연구하였다. Binary CDMA is a new standard technology for wireless communication developed by Korea that makes high speed communications and good quality of services. In this paper we researched on the development methods and design of a wireless VoIP system based on the Binary-CDMA technology that makes it freely installed in any place without phone cables and laying works.

가상 운동 훈련 프로그램(Wii fit)이 여성노인들의 균형증진에 미치는 영향

최재원,정현애,김은비,류애리,박소영,조경미,오미희,Choi, Jae-Won,Chung, Hyun-Ae,Kim, Eun-Bi,Ryu, Ae-Ri,Park, So-Young,Cho, Kyung-Mi,Oh, Mi-Hee 대한고유수용성신경근촉진법학회 2010 PNF and Movement Vol.8 No.3

Purpose : The purpose of this study was to investigate the effects of virtual exercise training programs on the improvement of balance in the elderly women. Methods: The subjects were fifteen female citizens, 67 years of age or older living in G city, the subjects were randomly divided into groups; Virtual exercise training group(n=9), control group (n=6). After treatment measured balance by Berg Balance scale test and One-leg stand test during virtual exercise training program at pre-intervention and post-intervention. Results : The results of this study were as follows : Virtual Exercise Training Program (Wii fit) after applying the Berg balance test scores and One-Legged Stance Test, the evaluation results showed significant results(p<05). Conclusion : Virtual exercise training programs can be used to improve the balance of the elderly, as it has been shown to increase Berg balance test and one-leg stand results conducted after virtual training programs. Virtual Exercise Programs(Wii fit) were applied to demonstrate the effecting the balance of the elderly to promote more research on the impact of the ADL survey.

$^1H-NMR$과 WAXS를 이용한 폴리(트리메틸렌 테레프탈레이트)/폴리(트리메틸렌 나프탈레이트) (50/50) 블렌드의 에스터 교 환반응 연구

최재원,오태환,김영호,Choi, Jae-Won,Oh, Tae-Hwan,Kim, Young-Ho 한국섬유공학회 2005 한국섬유공학회지 Vol.42 No.5

Poly(trimethylene terephthalate) (PIT) and poly(trimethylene naphthalate) (PTN) blends of 50/50 weight ratio, T5N5, were prepared by solution blending-precipitation method, and the effect of melting time on the degree of randomness, sequence length, and crystalline structure of melt-pressed blends obtained by melting T5N5 on a hot stage at $260^{\circ}C$ for different times and quenching into liquid nitrogen was studied using DSC, $^1H-NMR$ and WAXS. The T5N5 blend showed two $T_gs$ corresponding to that of PTT and PTN, which indicated that PTT and PTN were immiscible. But the melt-pressed blends melted at $260^{\circ}C$ for 2 minutes or more showed single $T_g$ indicating that the system became miscible. $^1H-NMR$ analysis confirmed that the blends became block copolymers and that the degree of randomness increased as melting time increased. The sequence length of PTT component was larger than that of PTN in the resultant copolymer. Although PTT and PTN were present in the same amount in the blend, PTT component crystallized more easily than the PTN component due to the larger block length of PTT. The crystalline structure of the component polymers was the same as that of homopolymers. The WAXS patterns showed that the crystalline structure of PTN in the melt-pressed blends was $\beta-form$ when they were annealed at $180^{\circ}C$ but it was a-form when annealed at $140^{\circ}C$, exhibiting the same behavior as homo PTN.

고조파 조절 회로를 기반으로 한 출력 정합 회로를 이용한 저위상 잡음 전압 제어 발진기

최재원,서철헌,Choi, Jae-Won,Seo, Chul-Hun 대한전자공학회 2008 電子工學會論文誌-TC (Telecommunications) Vol.45 No.2

In this paper, a novel voltage-controlled oscillator(VCO) using the output matching network based on the harmonic control circuit is presented for improving the phase noise property. The phase noise suppression is achieved through the harmonic control circuit having the short impedances for both second-harmonic and third-harmonic components, which has been connected at the output matching network. Also, we have used the microstrip square open loop multiple split-ring resonator(OLMSRR) having the high-Q property to further reduce the phase noise of VCO. Because the output matching network based on the harmonic control circuit has been used for reducing the phase noise property instead of the High-Q resonator, we can obtain the broad tuning range by the low-Q resonator. The phase noise of the proposed VCO using the output matching network based on the harmonic control circuit and the microstrip square OLMSRR has been $-127.5{\sim}126.33$ dBc/Hz @ 100 kHz in the tuning range, $5.744{\sim}5.839$ GHz. Compared with the reference VCO using the output matching network without the harmonic control circuit and the microstrip line resonator, the phase noise property of the proposed VCO has been improved in 26.66 dB. 본 논문에서는 위상 잡음 특성을 개선하기 위하여 고조파 조절 회로를 기반으로 한 출력 정합 회로를 이용한 전압 제어 발진기를 제안하였다. 위상 잡음은 2차, 3차 고조파 모두에서 단락 임피던스를 갖는 고조파 조절 회로를 통하여 억제되었으며, 출력 정합 회로에 연결되었다. 또한 전압 제어 발진기의 위상 잡음 특성을 더욱 더 개선하기 위하여 마이크로스트립 사각 개방 루프 다중 SRR를 이용하였다. 위상 잡음 특성 개선을 위하여 높은 Q값을 갖는 공진기 대신에 고조파 조절 회로를 기반으로 한 출력 정합 회로를 이용하였기 때문에 낮은 Q값을 갖는 공진기를 통하여 넓은 주파수 조절 범위를 얻을 수 있다. 고조파 조절 회로를 기반으로 한 출력 정합 회로와 마이크로스트립 사각 개방 루프 다중 SRR를 이용한 제안된 전압 제업 발진기의 위상 잡음 특성은 주파수 조절 범위, $5.744{\sim}5.839$ GHz에서 $-127.5{\sim}-126.33$ dBc/Hz @ 100 kHz이다. 고조파 조절 회로가 없는 출력 정합 회로와 마이크로스트립 선로 공진기를 이용한 전압 제어 발진기와 비교했을 경우, 제안된 전압 제어 발진기의 위상 잡음 특성은 26.66 dB 개선되었다.

마이크로스트립 사각 개방 루프 공진기와 가변 부성 저항을 이용한 저위상 잡음 Push-Push 전압 제어 발진기

최재원,서철헌,Choi, Jae-Won,Seo, Chul-Hun 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.8

본 논문에서는 마이크로스트립 사각 개방 루프 공진기와 가변 부성 저항을 이용한 향상된 push-push 전압제어 발진기를 제시하였다. 마이크로스트립 사각 개방 루프 공진기는 큰 결합 계수 값을 갖는데, 이는 Q값을 크게 만들고, 전압 제어 발진기의 위상 잡음을 줄인다. 1.8V의 공급 전압을 사용한 전압 제어 발진기는 $5.744{\sim}5.859GHz$의 주파수 조절 범위에서 $-124.67{\sim}-122.67dBc/Hz\;@\;100 kHz$의 위상 잡음 특성을 갖는다. 이 전압 제어 발진기의 FOM은 같은 주파수 조절 범위에서 $-202.83{\sim}-201dBc/Hz\;@\;100 kHz$의 값을 갖는다. 마이크로 스트립 사각 개방 루프 공진기를 이용한 단일 종단 전압 제어 발진기와 마이크로스트립 공진기를 이용한 push-push 발진기와 비교했을 때 개선된 위상 잡음 특성은 각각 -8.51 dB와 -33.67 dB이다. In this paper, a novel push-push voltage-controlled oscillator(VCO) using microstrip square open loop resonator and tunable negative resistance is presented. The microstrip square open loop resonator has the large coupling coefficient value, which makes a high Q value, and has reduced phase noise of VCO. The VCO with 1.8V power supply has phase noise of $-124.67{\sim}-122.67dBc/Hz\;@\;100 kHz$ in the tuning range, $5.744{\sim}5.859 GHz$. The FOM of this VCO is $-202.83{\sim}-201dBc/Hz\;@\;100 kHz$ in the same tuning range. When it has been compared with single-ended VCO using microstrip square open loop resonator, and push-push oscillator using microstrip line resonator, the reduced phase noise has been -8.51dB, and -33.67dB, respectively.

Microstrip Square Open Loop와 Tunable Negative Resistance를 이용한 저위상 잡음 전압 제어 발진기

최재원,이종민,서철헌,Choi, Jae-Won,Lee, Chong-Min,Seo, Chul-Hun 한국전자파학회 2006 한국전자파학회논문지 Vol.17 No.12

마이크로스트립 개방형 루프 공진기는 발진기의 위상 잡음을 줄이기 위해서 적용되었다. 마이크로스트립 스퀘어 개방형 루프 공진기는 큰 결합 계수 값을 가지고, 이로 인해 높은 Q 값을 가지며 전압 제어 발진기의 위상잡음을 감소시킨다. 전압 제어 발진기의 주파수 조절 범위를 증가시키기 위하여 버랙터 다이오드가 전압 제어발진기의 조절 가능한 부성 저항에 연결되어졌다. 전압 제어 발진기의 출력 파워와 하모닉 특성은 각각 4.83dBm과 -28.83 dBc이다. 위상 잡음 특성은 주파수 조절 범위 $5.735{\sim}5.845GHz$에서 $-112.33{\sim}-116.16dBc/Hz$ @ 100 kHz이다. The microstrip square open loop resonator has been employed to reduce the phase noise in VCO. The microstrip square open loop resonator has the large coupling coefficient value, which makes a high Q value, and has reduced the phase noise of VCO. To increase the tuning range of VCO, varactor diode has been connected at the tunable negative resistance in VCO. The output power and harmonic characteristics of VCO has been obtained 4.83 dBm and -28.83 dBc, respectively. The phase noise of VCO has been $-112.33{\sim}-116.16dBc/Hz$ @ 100 kHz in the tuning range, $5.735{\sim}5.845GHz$.

u-Campus 실현을 위한 유비쿼터스 종합정보시스템의 개발방법 및 설계

최재원,Choi, Jae-Won 한국정보통신학회 2010 한국정보통신학회논문지 Vol.14 No.2

본 논문에서는 언제 어디서나 대학의 인적 물적 지적 정보를 효율적으로 접근할 수 있고, 인터넷폰(VoIP), 이메일, 통합메세징, 인스턴트메시징, 웹컨퍼런싱, 화상회의 등의 다양한 커뮤니케이션 도구를 통해 통신 협업할 수 있는 대학의 유비쿼터스 종합정보시스템(u-종합정보시스템)을 최소한의 비용으로 효과적으로 구축하기 위한 시스템의 개발방법과 설계에 관해 연구하였다. In this paper we researched the development methods and design of the Ubiquitous Integrated Information System (u-IIS) that makes efficiently access the experts and various kinds of intellectual and material information of the universities. And u-IIS supports various communication and cooperation tools such as VoIP, Email, Unified Messaging, Instant Messaging, Web Conferencing, Audio/Video Communication etc. We gave our focus to the methods and design that makes it possible to effectively implement the u-IIS with the least costs based on the available databases and infrastructures.