• Journal of KIISE:Computer Systems and Theory
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• v.27 no.6
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• pp.549-557
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• 2000

Distributed Memory Machine(DMM) is necessary for the effective computation of the data which is complicated and very large. Task scheduling is a method that reduces the communication time among tasks to reduce the total execution time of application program and is very important for the improvement of DMM. Task Duplicated based Scheduling(TDS) method improves execution time by reducing communication time of tasks. It uses clustering method which schedules tasks of the large communication time on the same processor. But there is a problem that cannot optimize communication time between task sending data and task receiving data. Hence, this paper proposes a new method which solves the above problem in TDS. Modified Task Duplicated based Scheduling(MTDS) method which can approximately optimize the communication time between task sending data and task receiving data by checking the optimal condition, resulted in the minimization of task execution time by reducing the communication time among tasks. Also system modeling shows that task execution time of MTDS is about 70% faster than that of TDS in the best case and the same as the result of TDS in the worst case. It proves that MTDS method is better than TDS method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.7
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• pp.1030-1040
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• 2018

In Distributed Mobility Management (DMM) protocol, the mobility functions are distributed to network edge closer to mobile users. DMM protocol has some advantages of low-cost traffic delivery, optimized routing path, high scalability. However, it needs many mobile anchors to exchange signaling messages and it results in a high signaling cost. Thus, previous works suggested the hybrid DMM protocol to reduce the high signaling cost for long-live sessions and this paper extends a hybrid scheme to the NEMO environment. The mobile routers are installed at vehicles and can move together with several mobile devices. So we can define the high-mobility property for mobile routers and suggest the hybrid scheme using this property. According to the high-mobility property of mobile routers, we can distribute the mobile anchors or allocate a centralized mobile anchor. In this paper, we mathematically analyze the performance of the proposed NEMO-enabled hybrid DMM protocol and show superior performance.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.448-453
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• 2003

In this study, the effects of oxygen component in fuel and exhaust gas recirculation(EGR) method on the exhaust emissions has been investigated for a D.I. diesel engine. It was tested to estimate change of exhaust emission characteristics for the commercial diesel fuel and oxygenate blended fuel which has five kinds of blending ratio. Dimethoxy methane(DMM) contains oxygen component 42.5% in itself. and it is a kind of effective oxygenated fuel for reduction of smoke emission. It was affirmed that smoke emission was decreased with increasing of DMM blending ratio. But, NOx emission was increased compared with commercial diesel fuel. It was needed a NOx reduction countermeasure that EGR method was used as a countermeasure for NOx reduction. It was found that simultaneous reduction of smoke and NOx emission was achieved with DMM blended fuel and cooled EGR method($10{\sim}15%$).

• Journal of Biosystems Engineering
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• v.31 no.6 s.119
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• pp.457-462
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• 2006

Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions from diesel engine are recognized main cause which influenced environment strong. In this study, the potential possibility of biodiesel fuel and oxygenates additives (dimethoxy methane) was investigated as an alternative fuel for a naturally aspirated direct injection diesel engine. The smoke emission of blending fuel (biodiesel fuel 90vol-% + DMM 10vol-%) was reduced in comparison with diesel fuel, that is, it was reduced approximately 70% at 2500 rpm, full load. But, power, torque and brake specific energy consumption didn't have no large differences. But, NOx emissions from biodiesel fuel and DMM blended fuel were increased compared with commercial diesel fuel.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.183-186
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• 1995

The fabrication of dielectric multilayer mirror(DMM) optimized at the wavelength of 1.55$\mu\textrm{m}$ and its spectral properties were investigated. The materials used in the fabrication of DMM are TiO$_2$-SiO$_2$, which have the advantage of yielding high reflectance for relatively small numbers of layers. The optical constants of TiO$_2$single film were obtained by using a modified envelope method. The reflectances of DMMs with 3,7,11 and 23 layers were 58%, 89%, 97% and 99.9% at the wavelength of 1.55$\mu\textrm{m}$, respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.168-171
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• 2006

Hot deformation behavior of A350 LF2 alloy was characterized by compression tests in the temperature range of 800-$1250^{\circ}C$ and the strain rate range of $0.001-10s^{-1}$. The microstructural evolution during hot compression was investigated and deformation mechanisms were analyzed by constructing processing map. Processing maps were generated using the dynamic material model (DMM). The combination of dynamic material model and Ziegler's instability criterion was applied to predict an optimum condition and unstable regions for hot forming.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1798-1802
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• 2013

We present a technique for measuring low resistance ranges of a decade resistor with a 4-Terminal connection. With the technique the accuracy of 0.8 % was obtained for a 1 $m{\Omega}$ resistance of the decade resistor. We suggested a proper pattern 4-Terminal measurement results with several 4-Terminal pattern and adapters. Additionally, we should that precise measurements for low resistance can be made usung a digital multimeter(DMM) only.

• Electronics and Telecommunications Trends
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• v.31 no.1
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• pp.14-24
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• 2016

최근 ITU-R의 5G 서비스 및 성능 요구사항의 기준을 시작으로 각 표준화 단체 및 국가에서는 2020년을 목표로 5G에 대한 연구가 활발히 이루어지고 있다. 이 논문은 5G 서비스 및 기술적인 요구사항을 충족시킬 수 있는 네트워크 구조의 동향에 대해 살펴보고, 특히 5G 네트워크를 위한 이동성 관리 기술동향을 소개한다. 또한, 기존 4G 네트워크의 중앙집중형 이동성 관리 기술이 5G 서비스를 제공하는 데에 어떤 단점이 있을지에 관해 기술한 다음, 분산형, 평면형 이동성 관리 기술로 대표적인 Locator-Identifier Separation Protocol(LISP)과 Distributed Mobility Management(DMM) 기술을 소개하여, 각 이동성 관리 기술의 특징 및 장단점을 비교한다. 마지막으로, 5G에서의 이동성 관리 기술 요구사항을 도출하여, LISP과 DMM의 적용 가능성을 분석하여 최적의 5G 이동성 관리 기술을 도출하는 데 도움을 주고자 한다.

• The KIPS Transactions:PartA
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• v.8A no.1
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• pp.36-41
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• 2001

In this paper, we first design an parallel quadratic sieve algorithm for factoring method. We then present parallel factoring algorithm for factoring a large odd integer by repeatedly using the parallel quadratic sieve algorithm based on the divide-and-conquer strategy on SIMD machines with DMM. We show that this algorithm is optimal in view of the product of time and processor numbers.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.44-51
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• 2003

By blending of various low boiling point oxygenated agents to lower grade fuels, significant improvements were simultaneously obtained in smoke, CO, PM, SOF and BSEC. Especially, our trends were remarkably obtained by retarding injection timing, by decreasing boiling point and increasing blending contents of additives in case of oxygenated agents rather than non-oxygenated agents. Also, it was revealed that when 20vo1.% DMM added to high viscosity fuels and injection timing was retarded, NOx-smoke trade off relationship was much better than that of ordinary diesel fuel. Thus, lower grade fuels with high viscosity could be expected to be used efficiently and cleanly in diesel operation by blending low boiling point oxygenates.