• 한국군사과학기술학회지
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• 제9권1호
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• pp.50-59
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• 2006

Lately, there exist growing demands for the use of CTAs(Cased Telescoped Ammunitions) to increase the firepower of mid-calibre automatic guns despite spatial limitations of armament. In this paper, for automatic CTA guns a rotating chamber mechanism is designed based on parallel index concept. Via dynamic simulations it proves capable of smooth operation even at as high a firing rate as 200spm. Subsequently, motor controllers are synthesized to drive the chamber at any constant speed and also to control positions in the presence of large disturbances caused by the intermittently-rotating load. It is remarkable that we successfully adopted a disturbance observer to treat disturbances only with a moderate bandwidth of the closed-loop system.

• 한국건설관리학회논문집
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• 제13권1호
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• pp.67-76
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• 2012

공공공사의 물가변동률 산정방식은 지수조정과 품목조정 방식이 있으며, 관련법규에서는 품목조정방법을 원칙으로 삼고 있으나 대다수의 건설현장에서는 지수조정의 방법으로 계약금액조정이 이루어지고 있다. 이에 본 연구는 지수조정과 품목조정 방식의 직접적 상호 비교분석을 통해 차이의 정도 및 차이 발생 원인을 규명함으로써 조정방법간 차이에 따른 불균등을 해소하였으며, 각각의 방법에서 발견되어지는 불합리성에 대한 합리적 방안을 제시하였다. 공공주택건설공사의 건축공사를 대상으로 동일공사의 공사원가요소 즉, 직접재료비, 직접노무비, 실적공사비의 지수조정과 품목조정방법에 의한 세부 등락률을 산정하여 두 가지 조정방법간 차이를 분석하고 그 원인을 규명하였다. 분석결과 품목조정의 방법이 분석 전반에서 지수 조정에 비해 등락률이 낮게 산출되었으며, 차이발생의 주요원인으로 견적단가의 등락률 산정방법 상이, 공사종류 및 공사특성과 무관한 지수 적용 등에 기인한 결과로 분석되었다. 본 연구는 계약당사자간 원활한 계약금액조정을 위하여 조정방법간 차이를 직접 대응하여 비교분석하는 방법으로, 실제 발생되는 차이를 실체적으로 증명하였다는 점에 의의가 있다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.166-171
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• 2004

In this study, shape optimization of micro-static mixer with a cantilever beam was accomplished for mixing the mixing efficiency by using successive response surface approximations. Variables were chosen as the length of cantilever beam and the angle between horizontal and the cantilever beam. Sequential approximate optimization method was used to deal with both highly nonlinear and non-smooth characteristics of flow field in a micro-static mixer. Shape optimization problem of a micro-static mixer can be divided into a series of simple subproblems. Approximation to solve the subproblems was performed by response surface approximation, which does not require the sensitivity analysis. To verify the reliability of approximated objective function and the accuracy of it, ANOVA analysis and variables selection method were implemented, respectively. It was verified that successive response surface approximation worked very well and the mixing efficiency was improved very much comparing with the initial shape of a micro-static mixer.

• Journal of Mechanical Science and Technology
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• 제15권5호
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• pp.639-645
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• 2001

Experimental investigations were conducted to study forced convection of fully developed turbulent flows in horizontal equilateral triangular ducts with different surface roughness pitch ratios (P/e) of 4, 8, and 16 on one side. The ducts bottom wall was heated uniformly and the other surfaces were thermally insulated. To understand heat transfer enhancement mechanism, heat transfer rates were measured. Smooth triangular ducts were also tested for benchmark purposes. The results were compared with previous results for similarly configured channels, at which they were roughened by regularly spaced transverse ribs in the rectangular and circular channels.

• 대한안전경영과학회지
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• 제10권3호
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• pp.253-265
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• 2008

In this paper, we developed a heuristic algorithm to assign job to workers in parallel line inspection process without sequence. Objective of assigning job in inspection process is only to assign job to workers evenly. But this objective needs much time and effort since there are many cases in assigning job and cases increase geometrically if the number of job and worker increases. In order to solve this problem, we proposed heuristic algorithm to assign job to workers evenly. Experiments of assigning job are performed to evaluate performance of this heuristic algorithm. The result shows that heuristic algorithm can find the optimal solution to assign job to workers evenly in many type of cases. Especially, in case there are more than two optimal solutions, this heuristic algorithm can find the optimal solution with 98% accuracy.

• 제어로봇시스템학회논문지
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• 제5권5호
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• pp.511-520
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• 1999

An anti-reset windup (ARW) based compensation method for state constrained control systems is studied. First, a linear controller is constructed to give a desirable nominal performance ignoring state-constraints of a plant. Then, an additional compensator is introduced to provide smooth performance degradation under state-constraints of the plant. This paper focuses on the effective design method of the additional compensator. By minimizing a reasonable performance index, the proposed compensator is expressed in terms of theplant and ocntroller parameters. The resulting dynamics of the compensated controller exhibits the dominant part of the linear closed-loop system which can be seen from the singular perturbation model reducton theory. THe proposed method guarantees total stability of overall resulting systems if linear controllers were constructed to meet certain condition.

• 한국세라믹학회지
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• 제44권10호
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• pp.585-588
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• 2007

Silicon nitride films for an anti-reflection coating were deposited on silicon via RF magnetron sputtering using a $Si_3N4$ target. The best result was obtained at the sputtering condition of 340 W RF power, 5 mtorr Ar atmosphere, $100^{\circ}C$ substrate temperature. The films showed 7.9% reflectance minimum with 2.35 refractive index. 0.21 absorption coefficient at 66.6 nm thickness. The surface morphology showed a smooth and dense film with good adhesion to silicon surface.

• 한국공작기계학회논문집
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• 제11권5호
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• pp.88-92
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• 2002

This research is about slurry wear of SM45C and SUS304, which using standard sand and KUM river sand. The results are as follows ; 1. Mass loss rates of both standard sand and KUM river sand were linearly increased as increasement of time and velocity. 2. The average diameter of sand from relatively, less wear rate and portion of larger particles. 3. Wear resistance was linear with time and velocity of liquid jet regardless of type of sand. Also, it was able to evaluate with the formula, $HV^2$/E calibrated with n, the velocity index. 4. The wear surface in liquid jet experiment was smooth. The maximum wear depth was observed at the location 2~4mm apart from the center in the condition of $90^{\circ}$ of collision angle 6mm of nozzle diameter, and 20mm of collision distance. The sectional shape in radial appeared as 'W'shape.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.798-801
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• 2001

This research is about slurry wear of SM45C and SUS304, which using standard sand and KUM river sand. The results are as follows ; 1. Mass loss rates of both standard sand and KUM river sand were linearly increased as increasement of time and velocity. 2. The average diameter of sand from relatively, less wear rate and portion of larger particles. 3. Wear resistance was linear with time and velocity of liquid jet regardless of type of sand. Also it was able to evaluate with the formula, HV2/E calibrated with n, the velocity index. 4. The wear surface in liquid jet experiment was smooth. The maximum wear depth was observed at the location, 2~4mm apart from the center in the condition of 90$^{\circ}$of collision angle 6mm of nozzle diameter, and 20mm of collision distance. The sectional shape in radial appeared as 'W' shape.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.590-595
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• 1992

An integrated guidance scheme for guided weapon system is described in this paper. Against conventional guidance methods, this method combines an autopilot and a guidance law. The controller is designed using LQ regulator whose performance index is different from other optimal guidance laws. Since dynamics of the system is considered in the derivation, the controller performance is improved. By simulation, the suggested method shows better performance in minimum distance sense than conventional guidance schemes such as Bang Bang guidance or Pursuit Guidance. Since the suggested method provides smooth rudder deflection in contrast to the conventional method, the load on a energy source of the system can be greatly lessened.