• The Plant Pathology Journal
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• 제16권4호
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• pp.189-199
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• 2000

To search for the antifungal substances, various actino-mycete isolates were obtained from various soils of Korea using plate dilution method on the humic acid vitamin agar plates. In the screening procedures using a dual culture method, 32 actionomycete isolates were selected, which showed the inhibitory activity against mycelial growth of plant pathogenic fungi Altirnaria mali, Colletotrichum gloeosporides, Fusarium oxysporum f.sp. cucumerinum, Magnaporthe grisea, Phytophthora capsici, and Rhizoctonia solani. Bioassay of the crude extracts from culture filtrates and mycelial mets revealed that 12 antagonistic actionomycetes produced highly active antifungal substances. Actinomycete strain S5-55 which showed the substantial antifungal activity against the tested fungi was selected for production of the antifungal substances. Based on the cytochemical and morphological characteristics, strain S5-55 was identified as a Streptomyces species. The results of the numerical identification using the TAXON program confirmed that Streptomyces strain S5-55 was identical with Streptomyces humidus including in TAXON major cluster 19. The production of antifungal substance was most favorable when S. humidus strain S5-55 was cultivated for 10 dats on soluble starch broth supplemented with $K_2$HPO$_4$. The antifungal substances active against the plant pathogenic fungi P. capsici and M. grisea were partially purified using $\textrm{C}_{18}$ reversed-phase column chromatography.

• 한국정밀공학회지
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• 제12권5호
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• pp.57-68
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• 1995

A general procedure for the numerical solution of coupled, nonlinear, differential two-point boundary-value problems, solutions of which are crucial to the controller design, has been developed and demonstrated. A fixed-end-points, free-terminal-time, optimal-control problem, which is derived from Pontryagin's Maximum Principle, is solved by an extension of Davidenko's method, a differential form of Newton's method, for algebraic root finding. By a discretization process like finite differences, the differential equations are converted to a nonlinear algebraic system. Davidenko's method reconverts this into a pseudo-time-dependent set of implicitly coupled ODEs suitable for solution by modern, high-performance solvers. Another important advantage of Davidenko's method related to the time-optimal problem is that the terminal time can be computed by treating this unkown as an additional variable and sup- plying the Hamiltonian at the terminal time as an additional equation. Davidenko's method uas used to produce optimal trajectories of a single-degree-of-freedom problem. This numerical method provides switching times for open-loop control, minimized terminal time and optimal input torque sequences. This numerical technique could easily be adapted to the multi-point boundary-value problems.

• 국제강구조저널
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• 제18권5호
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• pp.1508-1524
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• 2018

Hysteretic energy dissipating devices (HEDDs) have been increasingly applied to building construction to improve the seismic performance. The seismic responses of such damped structures are significantly affected by HEDD's structural properties. An accurate investigation on the propagation of HEDD's structural properties is required for reasonable evaluation of the seismic performance of a structure. This study aims to develop simplified methods that can estimate the collective uncertainty-propagation to the seismic response of damped structures employing HEDDs. To achieve this, three- and six-story steel moment-resisting frames were selected and the propagations of the individual HEDD's property-uncertainties were evaluated when they are subjected to various levels of seismic demand. Based on the result of individual uncertainty-propagations, a simplified method is proposed to evaluate the variation of seismic response collectively propagated by HEDD's property-uncertainties and is verified by comparing with the exact collective uncertainty-propagation calculated using the Monte Carlo simulation method. The proposed method, called as a modified SRSS method in this study, is established from a conventional square root of the sum of the squares (SRSS) method with the relative contributions of the individual HEDD's property-uncertainty propagations. This study shows that the modified SRSS method provides a better estimation than the conventional SRSS method and can significantly reduce computational time with reasonable accuracy compared with the Monte Carlo simulation method.

• Corrosion Science and Technology
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• 제5권5호
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• pp.173-176
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• 2006

Previous national studies on costs of corrosion are reviewed and brief explanations are given of the Uhlig method, Hoar method and Input-output method that are employed for corrosion cost estimation. Total costs of corrosion of 11 countries are summarized and the results by Uhlig methods are compared especially for the recent studies from the U.S, Japan and China.

• 한국세라믹학회지
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• 제25권5호
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• pp.495-501
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• 1988

Verneuil method uses oxyhydrogen flame for its heat source. This method was used to grow corundum monocrystals. Parametersof this method are feeding rate, gas pressure, lowering rate and growth axis. These parameters were examined. Crystals's qualities and shapes are affected by these parameters. Crystals having good qualities and shape were grown under the conditions that feeding rate, 0.2∼0.5g/min, lowering rate, 10∼20mm/hr ; gas pressure, 3∼4psi ; growth axis was shifted 60 degrees from c axis.

• Advances in materials Research
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• 제5권4호
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• pp.263-277
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• 2016

Mechanical properties of $Al/Al_2O_3$ and $Al/B_4C$ composites prepared through powder metallurgy are estimated up to 50% $Al_2O_3$ and 35% $B_4C$ weight fractions using micromechanics models and experiments. The experimental Young's modulus up to 0.40 weight fraction of ceramic is found to lie closely between Ravichandran's/Hashin-Shtrikman lower/upper bounds, and close to self consistent method/Miller and Lannutti method/modified rule of mixture/fuzzy logic method single value predictions. Measured Poisson's ratio lies between rule of mixture/Ravichandran lower and upper bound/modified Ravichandran upper bounds. Experimental Charpy energy lies between Hopkin-chamis method/equivalent charpy energy/Ravichandran lower limit up to 20%, and close to the reciprocal rule of mixture for higher $Al_2O_3$ content. Rockwell hardness (RB) and Micro-hardness of $Al/Al_2O_3$ are closer to modified rule of mixture predictions.

• 비파괴검사학회지
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• 제18권5호
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• pp.381-388
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• 1998

비파괴검사법으로 잘 알려진 초음파법은 실제 현장적용에서 재료열화 손상을 평가하는데 주로 사용되고 있다. 그런데, 이 방법은 단지 튜브에 발생하는 균열의 크기와 두께 손실을 측정하는데 국한되어 사용되었다. 따라서 본 연구는 침탄열화된 재료의 손상평가에 초음파기술의 적용성을 조사하고, 초음파 특징과 침탄열화도 사이의 상호관계를 규명하는데 있다. 본 시편은 석유화학공장의 열분해관으로 널리 사용되는 재료인 HK-40 (25Cr-20Ni-0.4C) 주조관을 선택하여 침탄처리후 최소화된 시편크기 $40{\times}20{\times}6.3mm$로 제작하였다. 침탄처리는 $1200^{\circ}C$에서 고체침탄법을 적용하였다. 마이크로 비커스 경도시험에서 경도치는 탄화 석출물에 의해 표면에서 크게 증가하였다. 초음파 시험에서 종파속도는 침탄 깊이의 증가에 따라 증가하였으며, 비침탄제와 336 시간 침탄된 시편의 평균속도는 5MHz에서 각각 5,755 m/s, 5,840 m/s 값을 나타내고 있다. 이러한 연구결과를 바탕으로, 초음파 속도변화 특성을 이용한 침탄열화도 평가에 매우 유용한 방법으로 활용할 수 있을 것이다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
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• pp.117-124
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• 2001

A simplified method fur the eigenpair sensitivities of damped system with multiple eigenvalues is presented. This approach employs a reduced equation to determine the sensitivities of eigenpairs of the damped vibratory systems with multiple natural frequencies. In the proposed method, adjacent eigenvectors and orthonormal conditions are used to compute an algebraic equation whose order is (n+m)x(n+m), where n is the number of coordinates and m the number of multiplicity of multiple natural frequencies. The proposed method is an improved Lee and Jung's method which was developed previously. Two equations are used to find eigenvalue derivatives and eigenvector derivatives in Lee and Jung's method. A significant advantage of this approach over Lee and Jung's method is that one algebraic equation newly developed is enough to compute such eigenvalue derivatives and eigenvector derivatives. This method can be consistently applied to both structural systems with structural design parameters and mechanical systems with lumped design parameters. To demonstrate the theory of the proposed method and its possibilities in the case of multiple eigenvalues, the finite element model of the cantilever beam and 5-DOF mechanical system in the case of a non-proportionally damped system are considered as numerical examples. The design parameter of the cantilever beam is its height. and that of the 5-DOF mechanical system is a spring.

• 한국식품과학회지
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• 제22권5호
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• pp.582-589
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• 1990

본 고에서는 Equivalent time과 Equivalent temperature를 활용하여 Kinetic parameters를 결정하는 새로운 방법을 제안하였다. 본 방법의 타당성을 두 가지의 kinetic data 즉, 계산치와 실험치를 이용하여 예시하였다. 계산치는 그 Kinetics가 잘 알려진 세 가지 화학반응에 대해 임의의 등온가열조건을 적용하여 계산하였고 실험치는 2% 설탕용액을 사용하여 0.0005N 염산용액을 사용하여 가수분해가 일어나는 정도를 효소반응을 이용하여 측정하였다. 본 방법에 의해 결정된 활성화 에너지와 Frequency factor는 각각 $104.74{\pm}1.87KJ/mol$과 $5.26{\times}10^{14)hr^{-1}$이었으며 이들 값은 보고된 결과와 잘 일치되었다.

• 한국컴퓨터정보학회논문지
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• 제27권9호
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• pp.101-112
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• 2022

본 논문에서는 5G 네트워크 슬라이싱에 대해서 분석하고 5G 이동 통신망에서의 효율적인 네트워크 슬라이스 설정 방안을 제안한다. 5G 이동 통신망에서 네트워크 슬라이싱은 네트워크 슬라이스 인스턴스 정보에 기반하여 구분되고 수행된다. 단말과 네트워크 간의 네트워크 슬라이스 인스턴스 정보가 상호 일치하지 않는 경우, 단말의 PDU 세션 연결 요청 실패에 따른 불필요한 시그널링 오버헤드가 발생한다. 본 논문은 이러한 문제를 해결하기 위해서, 두 가지 효율적인 네트워크 슬라이스 설정 기법, 단말 기반 ENSC(Efficient Network Slice Configuration) 기법과 네트워크 기반 ENSC 기법을 제안한다. 제안하는 두 가지 기법들은 신속한 단말과 네트워크 간의 최신 변경 업데이트된 네트워크 슬라이스 정보를 제공 설정 수행하게 되어, 기존 방안과 비교하여 배터리 리소스 효율성을 향상시키고 불필요한 시그널링 오버헤드를 최소화할 수 있다.