• 지식경영연구
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• 제10권2호
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• pp.35-48
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• 2009

The paper proposes a quantitative causal ordering map (QCOM) to combine qualitative and quantitative methods in a framework. The procedures for developing QCOM consist of three phases. The first phase is to collect partially known causal dependencies from experts and to convert them into relations and causal nodes of a model graph. The second phase is to find the global causal structure by tracing causality among relation and causal nodes and to represent it in causal ordering graph with signed coefficient. Causal ordering graph is converted into QCOM by assigning regression coefficient estimated from path analysis in the third phase. Experiments with the prediction model of Korea stock price show results as following; First, the QCOM can support the design of qualitative and quantitative model by finding the global causal structure from partially known causal dependencies. Second, the QCOM can be used as an integration tool of qualitative and quantitative model to offerhigher explanatory capability and quantitative measurability. The QCOM with static and dynamic analysis is applied to investigate the changes in factors involved in the model at present as well discrete times in the future.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 1999년도 제1회 학술대회논문집(KIASC 1st conference 99)
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• pp.51-53
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• 1999

The crystallization mechanism of an amorphous $Bi_{2}$$Sr_{2}$$Ca_{2 x}$$Cd_{x}$$Cu_{3}$$O_{y}$ phase were studied from the relations between crystallization and volume changes by dilatometry. Further, the effect of addition of CdO on the crystallization mechanism and superconductivity was discussed. The shrinkage of the amorphous $Bi_{2}$$Sr_{2}$$Ca_{2 x}$$Cd_{x}$$Cu_{3}$$O_{y}$ occurred with the crystallization of $Bi_{2}$$Sr_{2}$Cu$O_{6}$ phase decrease with increasing CdO content with a minimum at x=0.4. Better superconductivity was obtained in the specimens formation less amount of the$Bi_{2}$$Sr_{2}$Cu$O_{6}$ phase during the crystallization process.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.365-367
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• 2010

In this paper, we presented the exact Riemann solver for the air-water two-phase shock tube problems where the strength of the propagated sock wave is moderately weak. The shock tube has a diaphragm in the middle which separates water medium in the left and air medium in the right. By rupturing the diaphragm, various waves such as rarefaction wave, shock wave and contact discontinuity are propagated into water and air. Both fluids are treated as compressible, with the linearized equations of state. We used the isentropic relations for the air and water assuming a weak shock wave. We solved the shock tube problem considering a high pressure in the water and a low pressure in the air. The numerical results cleary showed a left-traveling rarefaction wave in the water, a right-traveling shock wave in the air, and the right-traveling material interface.

• 설비공학논문집
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• 제8권1호
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• pp.99-109
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• 1996

Experimental investigations are carried out for the characteristics of bubble rise in the Miniature Two-Phase closed Thermosyphon(MTPCT) with a thin wire insert. The working fluids applied as experimental media are of three kinds: water, methanol, and ethanol. The effects of combination of the inclination with diametric ratio $\alpha$(=d$_{0}$/D$_{I}$) on rising velocity of a large bubble in the thermosyphon are explicitly analyzed. The realm of a movable bubble and the critical value of $\alpha$ are iteratively pursued to interpret the region Figures-of-Break, rooted in the governing physics relations, according to the application of working fluid. Experimental results are compared with those of analysis and critical ranges for $\alpha$ and D$_{I}$ were ascertained from comparisons.isons.

• Journal of Communications and Networks
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• 제6권1호
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• pp.78-87
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• 2004

This paper presents deterministic, worst-case analysis of a queueing system whose multiple homogeneous input streams are regulated by the associated leaky buckets and the queueing system that has a single stream regulated by the jumping-window. Queueing delay averaged over all items is used for performance measure, and the worst-case input traffic and the worst-case performance are identified for both queueing systems. For the former queueing system, the analysis explores different phase relations among leaky-bucket token generations. This paper observes how the phase differences among the leaky buckets affect the worst-case queueing performance. Then, this paper relates the worst-case performance of the former queueing system with that of the latter (the single stream case, as in the aggregate streams from many users, whose item arrivals are regulated by one jumping-window). It is shown that the worst-case performance of the latter is identical to that of the former in which all leaky buckets have the same phase and have particular leaky bucket parameters.

• 한국컴퓨터정보학회논문지
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• 제5권3호
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• pp.1-8
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• 2000

선코드 스케줄링은 코드 스케줄링을 먼저 수행함으로써 자료 종속 관계가 복잡해지고. 레지스터를 할당할 때 간섭그래프가 복잡해져 레지스터 할당을 어렵게 만들 수 있다. 본 논문에서는 이를 개선하기 위하여 2-단계 컬러링 기법을 제안한다. 단계 1에서 생존 거리가 큰 변수들에 레지스터 배정, 단계 2에서 나머지 변수들에 레지스터를 할당함으로써 레지스터 할당 소요 비용을 최소화한다. 실험 결과 기존의 방법에 비해 제안한 방법이 효율적임을 검증하였다.

• 대한전자공학회논문지
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• 제23권3호
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• pp.397-400
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• 1986

In this paper, the orthogonal properties of the eigenmodes of optical resonators which have phase conjugate mirrors at both ends are derived. The modes which propagate in resonators are descdribed by the Huygens integral. Then, the eigeneuqation which is needed in order to prove the orthogonality of the eigenmodes of the resonator is obtained from this representation. When the kernel being a part of the eigenequation is Hermitian as in conventional resonators and in optical resonator with only one phase conjugate mirror, one can show that the eigenmodes have essentially biorthogonal relations, which are satisfied the set of modes propagating in one direcdtion around the resonator and the adjoint set of modes propagating in the reversed direction.

• 한국정밀공학회지
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• 제11권2호
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• pp.95-103
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• 1994

The purpose of this paper is to provide the experimenters who use the oblique incidence ultrasonic method for anisotropic elastic constants measurement eith some useful relations. In particular, the equivalence of the times of flight by the energy ad phase velocities, which is key to the oblique incidence method, is proved explicitly. This equivalence greatly simplifies the analysis of immersion measurement results. In oredr to correctly measure the transit time of an immersed sample using the oblique incidence, the receiving transducer should be shifted laterally, and an expression in given for this shift. A method for determining all nine elastic constants of an orthotropic material is briefly described and the measurement results are listed for SiC particulate reinforced A1 matrix composites.

• Journal of Power Electronics
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• 제17권1호
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• pp.262-271
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• 2017

This paper studies the performances of five typical Phase-locked Loops (PLLs) for distorted and unbalanced grid, which are the Decoupled Double Synchronous Reference Frame PLL (DDSRF-PLL), Double Second-Order Generalized Integrator PLL (DSOGI-PLL), Double Second-Order Generalized Integrator Frequency-Lock Loop (DSOGI-FLL), Double Inverse Park Transformation PLL (DIPT-PLL) and Complex Coefficient Filter based PLL (CCF-PLL). Firstly, the principles of each method are meticulously analyzed and their unified small-signal models are proposed to reveal their interior relations and design control parameters. Then the performances are compared by simulations and experiments to investigate their dynamic and steady-state performances under the conditions of a grid voltage with a negative sequence component, a voltage drop and a frequency step. Finally, the merits and drawbacks of each PLL are given. The compared results provide a guide for the application of current control, low voltage ride through (LVRT), and unintentional islanding detection.

• 한국지구과학회지
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• 제23권1호
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• pp.105-111
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• 2002

The observation of the new biotite isograd (chlorite + chloritoid = andalusite + biotite) in the Mungyong coal field requires the modification of Harte and Hudson's (1979) metapelite grid which eliminates the stability field of staurolite + cordierite assemblages. The newly proposed metapelite grid by Ahn and Nakamura (2000) can define more properly the isograd reaction observed from nature. We discuss first topological interrelations between synthetic system (FASHO-, KFASHO-, KFMASH system) on an isobaric section at 2kbar, where phase relations are well constrained. The following discussion is concentrated on the topological relations between stable reactions. At the last, we discuss the petrogenetic significance of the Ahn's petrogenetic grid compared with theoretically computed grids. Ahn's petrogenetic grid is consistent with synthetic and natural system, and is one of the excellent example of KFMASH approximation in metapelite.