• 대한수학회보
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• 제54권3호
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• pp.1037-1067
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• 2017

Motzkin and Straus established a close connection between the maximum clique problem and a solution (namely graph-Lagrangian) to the maximum value of a class of homogeneous quadratic multilinear functions over the standard simplex of the Euclidean space in 1965. This connection and its extensions were successfully employed in optimization to provide heuristics for the maximum clique problem in graphs. It is useful in practice if similar results hold for hypergraphs. In this paper, we develop a homogeneous multilinear function based on the structure of hypergraphs and their complement hypergraphs. Its maximum value generalizes the graph-Lagrangian. Specifically, we establish a connection between the clique number and the generalized graph-Lagrangian of 3-uniform graphs, which supports the conjecture posed in this paper.

• 대한수학회보
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• 제52권6호
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• pp.2011-2023
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• 2015

This paper determines the structures of one-homogeneous weight codes over finite chain rings and studies the algebraic properties of these codes. We present explicit constructions of one-homogeneous weight codes over finite chain rings. By taking advantage of the distance-preserving Gray map defined in [7] from the finite chain ring to its residue field, we obtain a family of optimal one-Hamming weight codes over the residue field. Further, we propose a generalized method that also includes the examples of optimal codes obtained by Shi et al. in [17].

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1500-1505
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• 2003

In order to avoid the unit inconsistency problem in the conventional Jacobian matrix, previously we presented new formulation of a dimensionally homogeneous inverse Jacobian matrix for parallel manipulators with a planar mobile platform by using three end-effector points based on the velocity relationship [1]. This paper presents force relationships between joint forces and Cartesian forces at the three End-Effector points. The derived force relationships can then be used for analyses of the input/output force transmission. These analyses, forward and inverse force transmission analyses, depend on the singular values of the derived dimensionally homogeneous Jacobian matrix. Using the proposed force relationship, a numerical example is presented for actuator size design of a 3-RRR planar parallel manipulator.

• 한국분무공학회지
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• 제11권3호
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• pp.161-167
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• 2006

As the exhaustion of petroleum resources and air pollution problems are getting serious recently, there are growing interests in premixed diesel engines which have the potential of achieving a more homogeneous mixture near TDC compared to conventional diesel engines. Early studies have shown that the fuel injection frequency and spray angle affected the mixture formation and combustion in a HCCI(Homogeneous Charge Compression Ignition) engine. Therefore, the purpose of this study is to investigate the relationship between combustion and mixture formations by injection timing and frequency using a narrow angle injector, NADI (Narrow Angle Direct Injection). In this study, we found that the fuel injection timing and injection frequency affect the mixture formations and then affect combustion in the HCCI engine.

• 한국응용과학기술학회지
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• 제17권4호
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• pp.273-278
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• 2000

Cellulose tosylate(CT) was prepared by reaction of cellulose with p- toluenesulfonylchloride in DMAc/LiCl homogeneous system. In order to study a reversible photoisomerization of disperse red 1(DR-1) attached on natural polymer, cellulose tosylate containing DR-1(DR-1/CT adduct) was prepared at $110^{\circ}C$ in DMAc, and the changes of UV/Vis spectra of its solutions and thick film were investigated by alternate irradiation technique. Form the UV/Vis spectra of DR-1/CT adduct dissolved in cosolvents, such as DMAc, DMAc/THF, DMAc/benzene, and DMAc/chloroform and irradiated with 360 nm and 450 nm ligths, we found out changes of UV/Vis spectra were reversible in all solvents systems and we found out changes of UV/Vis spectra were reversible at thick film, also.

• 공학교육연구
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• 제15권6호
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• pp.43-48
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• 2012

This study was conducted to compare team creativity and creative problem solving styles between heterogeneous and homogeneous teams. Team composition was based on the levels of openness and extraversion. The results indicated that heterogeneous teams showed higher team creativity scores than homogeneous teams. Frequency distributions of creative problem solving styles indicated that heterogeneous team members preferred developer, external, and task-oriented styles. Homogeneous team members preferred explorer and person-oriented styles. Finally, limitations of this study and suggestions for future studies were discussed.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제23권3호
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• pp.319-328
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• 2016

In this paper, we solve the additive ρ-functional inequalities (0.1) ||f(2x-y)+f(y-x)-f(x)|| $\leq$ ||${\rho}(f(x+y)-f(x)-f(y))$||, where ρ is a fixed complex number with |ρ| < 1, and (0.2) ||f(x+y)-f(x)-f(y)|| $\leq$ ||${\rho}(f(2x-y)-f(y-x)-f(x))$||, where ρ is a fixed complex number with |ρ| < $\frac{1}{2}$. Using the direct method, we prove the Hyers-Ulam stability of the additive ρ-functional inequalities (0.1) and (0.2) in β-homogeneous F-spaces.

• 한국재난정보학회:학술대회논문집
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• 한국재난정보학회 2016년 정기학술대회
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• pp.388-390
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• 2016

본 연구에서는 금강유역의 가뭄과 한반도 주변 지역의 기후 인자들과의 상관관계를 파악하고 이를 바탕으로 기후변화 시나리오를 이용하여 미래의 가뭄을 예측하였다. 1974 - 2015년 동안 11 - 5월에 발생한 강우 자료와 NOAA에서 제공하는 NCEP-NCAR 자료를 이용하여 한반도 주변 기후인자와 금강유역의 강우가 과거 발생한 가뭄과 어떠한 상관관계를 갖는지를 분석하였다. 금강유역의 강우 패턴을 4개의 스테이지로 구분한 후 이를 상태층으로 참고하였으며, 관측 자료는 학습단계에 활용하였다. 이러한 기후인자와 강우 관계의 학습 결과를 바탕으로 기후변화 시나리오를 적용하고 미래의 기후요소를 예측하였으며 이를 통해 미래 금강유역의 가뭄을 예측하였다. 본 연구의 결과는 금강권역 수자원 공급 계획 및 설계의 기초자료로 제공될 수 있으며, 가뭄 대비 대책 사업의 우선순위 결정에 대한 근거 자료로 활용될 수 있을 것으로 기대된다.

• 한국자동차공학회논문집
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• 제11권2호
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• pp.119-125
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• 2003

An experiment study on pressure drop was carried out for both an adiabatic and a diabatic two-phase flow with pure refrigerants R134a and Rl23 and their mixtures as test fluids in a uniformly heated horizontal tube. The frictional pressure drop during flow boiling is predicted by using two models; the homogeneous model that assumes equal phase velocity and the separate flow model that allows a slip velocity between two phases. The measured frictional pressure drop was compared to a few available correlations. Homogeneous model considerally underpredicted the present data for mixture as well as pure component in the entire mass velocity ranges employed in the present study, while Friedel correlation was found to satisfactorily correlate the frictional pressure drop data as compared to other correlation.

• 센서학회지
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• 제27권1호
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• pp.25-30
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• 2018

Closed-form analytical expressions and 3-dimensional normalized charts for the homogeneous sensing and surface sensing structures are derived to provide the conditions for the maximum sensitivity of integrated-optic biosensors based on evanescent-wave and stepindex planar optical waveguides. The analysis is made for transverse electric (TE) polarization mode, in both cases where the measurand is homogeneously distributed in the cover (namely, homogeneous sensing), and where it is an ultrathin film on the waveguide-cover interface (namely, surface sensing).