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와이브로 망에서 IPv6 이동 단말의 교차 계층 핸드오버 기법
장희진(Hee-Jin Jang),한연희(Youn-Hee Han),황승희(Seung-Hee Hwang) 한국정보과학회 2007 정보과학회논문지 : 정보통신 Vol.34 No.1
국내의 와이브로 기술은 단말의 이동성을 지원하기 때문에 사용자가 임의의 서브넷 내부에서 이동 할 때에도 지속적인 인터넷 서비스를 제공한다. 또한, 차세대 인터넷 지원 기술인 IPv6 및 Mobile IPv6 (MIPv6)은 이동 단말에 주소를 할당하고, 이러한 단말들이 서로 다른 서브넷을 이동 할 때에도 기존의 인터넷 세션을 유지할 수 있도록 지원하는 최신 기술이다. 하지만, VoIP (Voice over IP)와 같은 실시간 서비스를 만족시킬 수준의 이동성을 지원하려면, 와이브로 망 및 단말에 최적화된 고속 IPv6 핸드오버 기술 개발이 선행되어야 한다. 본 논문에서는 IPv6 단말이 와이브로 망에서 서브넷 간 이동을 시도할 때, 핸드오버 지연 시간을 최소화하는 최적화된 핸드오버 기법을 제안한다. 제안하는 기법은 고속 핸드오버를 지원하기 위한 IETF 대표 프로토콜인 Fast Mobile IPv6 (FMIPv6)에 기반을 두고 있으며 2계층 와이브로 MAC (Medium Access Control)과 3계층 FMIPv6 과의 밀접한 상호 작용 및 관련 핸드오버 절차로 구성된다. 마지막으로, 수학적 성능 분석을 통하여 와이브로 망에서 운영되는 FMIPv6의 핸드오버 지연 시간을 계산하여 그 결과를 제시한다. WiBro (Wireless Broadband) service, developed in Korea, can provide the host mobility while its users hang around within the subnet. Next-generation Internet protocols, IPv6 and Mobile IPv6 (MIPv6), provide a plenty of addresses to the nodes and enable the handover between different subnets. However, MIPv6 is not enough to support a real time service such as VoIP (Voice over IP) due to the long latency, and it is necessary to develop an enhanced handover mechanism which is optimized to the WiBro networks. In this paper, we suggest an improved fast handover mechanism while the mobile node moves around WiBro networks. The proposal is based on Fast Mobile IPv6(FMIPv6) which is the representative protocol for fast handover, and reduces the handover latency by the close interaction between the link layer (WiBro MAC) and IP layer (FMIPv6). Finally, we analyze the performance of proposed mechanism through the mathematical analysis.
pH 8.5 완충용액에서 형성된 Ni-(15,30)Cr 합금의 부동태 피막의 반도체적 특성에 관한 연구
장희진 ( Hee Jin Jang ) 조선대학교 공학기술연구원 2009 공학기술논문지 Vol.2 No.2
The semiconducting properties of the passive films formed on Ni-(15, 30)Cr alloys in pH 8.5 buffer solution were examined by XPS, photoelectrochemical technique, and Mott-Schottky analysis. From XPS analysis, the concentration of Ni was higher than or comparable to that of Cr in passive film formed on Ni-(15, 30)Cr in pH 8.5 buffer solution. The photocurrent spectrum for the passive film formed on those alloys in pH 8.5 buffer solution were found to be induced by NiO, Ni(OH)2, and Cr(OH)3. The Intensity of photocurrent, particularly of the component assigned to hydroxides, was significantly decreased with increase in Cr content in !he alloys, indicating Cr suppresses formation of hydroxides. The Mott-Schottky plot for the passive films on Ni-( 15, 30)Cr alloys showed similar behavior to that for the film on Ni. The acceptor density, indicating the concentration of cation "vacancy, was reduced by increasing Cr content in Ni-(15, 30)Cr alloys.
반응표면분석법을 활용한 Fe-18Cr 스테인리스강의 부식 및 산화 저항성에 미치는 Ti, Si, Mo의 영향 분석
장희진 ( Hee Jin Jang ),윤귀섭 ( Kwi Sub Yun ),박찬진 ( Chan Jin Park ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.8
We studied the corrosion and oxidation properties of Fe-18Cr-0.4Nb-(0.1~0.6)Ti-(1~3)Si-(0.5~2)Mo stainless steel. The resistance to general and pitting corrosion was evaluated and the results were analyzed by Response Surface Methodology (RSM) as a function of alloy composition. The effects of alloy composition and heat treatment on the oxidation resistance were also examined. Mo increased both general corrosion resistance and pitting corrosion resistance. Si improved the resistance of the alloys to pitting corrosion. Si was also beneficial for general corrosion resistance of the alloys containing Mo at more than 1 wt.%. However, Mo was detrimental when its content was lower. Effects of Ti on general corrosion properties appeared to be weak and a high concentration of Ti appeared to deteriorate pitting resistance. The thickness of the oxidation scale increased and adhesion of the scale worsened as the temperature increased from 800℃ to 900℃. Weight gain of the alloys due to oxidation at 900℃ clearly showed that the resistance to oxidation is improved by annealing at 860℃ and an increase of Si content.
장희진 ( Hee Jin Jang ),( Suhn Yeop Kim ),( Hyun Jeong Jang ) 한국전문물리치료학회 2014 한국전문물리치료학회지 Vol.21 No.2
The objective of this study was to determine the duration of maintained calf muscle flexibility gained in young adults with calf muscle tightness, as measured by increases in ankle active and passive dorsiflexion range of motion (DFROM) after three stretching interventions. Twenty subjects (5 men and 15 women) with calf muscle tightness received the following three stretching interventions in one leg (assigned at random): static stretching (SS), eccentric training on stable surface (ETS), and eccentric training on unstable surfaces (ETU). The subjects received all three interventions to the same leg, applied in a random order. Each intervention had a break of at least 24 h in-between, in order to minimize any carryover effect. Each intervention used two types of stretching: with the calf muscle stretched and both knees straight, and with the knee slightly bent in order to maximize the activation of the soleus muscle. All three interventions were performed for 200 seconds. We measured the duration of maintained calf muscle flexibility through active and passive ankle DFROM before intervention, immediately after intervention (time 0), and then 3, 6, 9, 15, and 30 min after intervention. We found a difference in the duration of maintained calf muscle flexibility between the three interventions. In the ETS and ETU interventions, a significant improvement in calf muscle flexibility, both ankle active and passive dorsiflexion ranges of motion (ADFROM and PDFROM), was maintained for 30 min. In the SS intervention, however, ADFROM before 9 min and PDFROM before 6 min were statistically different from the baseline. Our results suggest that ETS and ETU may be more effective than SS for maintaining calf muscle flexibility in young adults.