• International journal of advanced smart convergence
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• 제8권4호
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• pp.26-33
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• 2019

We conducted research to evaluate economically and engineering about the synthesis of Magnesium Oxide, MgO, nanoparticles using physicochemical methods. The method used was economic evaluation by calculating GPM, BEP, PBP, and CNPV. The other method used was engineering perspective. MgO nanoparticles were synthesized by reacting Mg(NO₃)₂ and NaOH with a mole ratio 1: 2. Mg(OH)₂ formed was heated and calcined to remove water content and to oxidation to form MgO. An economic evaluation by calculating GPM and CNPV for the production of MgO nanoparticles on an industrial scale shows that the payback period (PBP) occur in the third year and profits increase each year. Tax variations show that the higher of tax, the lower profits received. When there was an increase of selling prices, the profit was greater. The variable cost used is the price of raw material. When there was an increased in the variable cost price, the payback period was longer and the profits was reduced. The benefit of this research is knowing the industrial production of MgO nanoparticles is beneficial. The function of MgO nanoparticles is a material for the manufacture of ceramics and can be used as an antimicrobial in the water filtration process.

• 유통과학연구
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• 제17권7호
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• pp.45-53
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• 2019

Purpose - The relationship between multinationality and performance has become a hot topic in academic circles and is very important for multinational firms, especially for Chinese multinational firms, who need more experience to enter the international market. Given this background, this paper attempts to figure out the importance of multinationality to China's firm performance and to explore whether the Four-stage Theory can also be applied to China's firms. Research design, data, and methodology - We employ the panel data of 435 multinational firms from 2008 to 2017 chosen from China's A-shares to conduct an empirical analysis by using a fixed-effects model. In the paper, the performance is represented by ROA (return on assets), treated as a dependent variable, and multinationality is represented by FSTS (foreign sales/total sales), treated as an independent variable. Results - We find that the performance first decreases then rises, then falls down, and rises again in the end. Hence there is a W-shaped relationship between the multinationality of the Chinese manufacturing industries and firm performance, proving that the four-stage theory is also applicable to Chinese multinational firms. Conclusions - These empirical results can provide some advice for policymakers to improve the firm performance such as reducing the logistics cost of multinationality.

• 시스템엔지니어링학술지
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• 제4권2호
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• pp.35-43
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• 2008

Application of system engineering should be realized on necessary condition being to propel National Defense R&D Program. But, these necessity is yet not realized easily to many project managers of Defense Acquisition Program Administration(DAPA). As one person of DAPA project manager, system engineering hard to approaches easily by the word itself. There are a lot of difficult sections where should apply how. This paper established DAPA Project Manager and Acquisition Point of Contact of demand Military by main customer (reader), and wished to make understood more easily and approach system engineering application to these. Also, this paper studied project management example that scientific project management techniques of Earned Value Management(EVM) and Cost As an Independent Variable(CAIV) etc. is taken abuzz in DAPA inside by Project management technique that become reform, arc Integrated in system engineering.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1199-1205
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• 1993

It has been well known that the assumption of full state availability is one of the most important restrictions to the practical realization of VSCS. And several attempts to alleviate the assumption had been made. However, it is not easy to find a positive scheme among them. Recently, an output feedback variable structure control system(OFVSCS) was proposed and the effectiveness of the scheme was validated for the disturbance free systems. The purpose of this study is to propose a robust OFVSCS that have the robust properties against process parameter variations and external distrubances by extending the basic OFVSCS and to evaluate its control performances through power system stabilizer design example. The ROFVSCS is composed of dynamic switching function and output feedback switching control inputs that are constructed by the use of the unknown vector modeling technique. With the proposed scheme, existence of sliding mode is guaranteed and any nonzero bias can be suppressed in the face of disturbances and process parameter variations as far as well-known matching condition is satisfied. Due to the fact that the ROFVSCS is driven by small number of measured informations, the practical application of VSCS for the systems with unmeasurable states and for high order systems that conventional schemes cannot be applied, is possible with the proposed scheme. It is noticeable that the implementation cost of VSCS can be considerably reduced without sacrifice of control performances by adopting ROFVSCS since there is no need measure the states with high measurement cost.

• 전자공학회논문지
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• 제51권5호
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• pp.106-113
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• 2014

최근 반도체 업계에서 주요 관심사로 떠오르고 있는 SOC(System-on-a-chip) 테스트는 비용 및 시간 절감을 위해 여러 종류의 FDR(Frequency-directed run-length) 기술이 제안되었다. 기존의 FDR보다 압축률을 향상시키는 EFDR(Extended-FDR)과 SAFDR(Shifted-Alternate-FDR), VPDFDR(Variable Prefix Dual-FDR)이 있다. 본 논문에서는 제안한 Frequency-ordered 방식은 FDR, EFDR, SAFDR, VPDFDR에 적용시켜 상당한 압축률 개선을 보인다. 본 기술을 사용하면 압축률을 극대화할 수 있고, 결과적으로 전체적인 양산 테스트 비용 및 시간을 크게 절감할 수 있게 한다.

• Structural Engineering and Mechanics
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• 제66권2호
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• pp.173-183
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• 2018

This paper proposes a developed optimization model for steel frames with semi-rigid beam-to-column connections and fixed bases using teaching-learning-based optimization (TLBO) and genetic algorithm (GA) techniques. This method uses rotational deformations of frame members ends as an optimization variable to simultaneously obtain the optimum cross-sections and the most suitable beam-to-column connection type. The total cost of members plus connections cost of the frame are minimized. Frye and Morris (1975) polynomial model is used for modeling nonlinearity of semi-rigid connections, and the $P-{\Delta}$ effect and geometric nonlinearity are considered through a stepped analysis process. The stress and displacement constraints of AISC-LRFD (2016) specifications, along with size fitting constraints, are considered in the design procedure. The developed model is applied to three benchmark steel frames, and the results are compared with previous literature results. The comparisons show that developed model using both LTBO and GA achieves better results than previous approaches in the literature.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2003년도 춘계공동학술대회논문집
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• pp.242-248
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• 2003

본 논문에서는 다양한 종류와 다양한 크기의 화물에 대해 3차원 적재하는 방법으로서 휴리스틱 기법을 이용한 해법을 제안하였다. 먼저, 컨테이너 비용을 적재비용, 수송비용 및 처리비용의 합으로 나타내며. 화물간 우선순위 및 화물 내에서의 개수 간 우선순위를 적용하였다. 주어진 화물을 적재 공간 및 중량을 만족하면서 위의 컨테이너 비용을 최소화하는 컨테이너 종류 및 개수를 산출하였으며, 적재 시 화물의 팔레타이져 및 디팔레타이져로서 컨테이너 내의 공간 이용률을 극대화시켰다. 마지막으로 화물의 무게 균등화를 고려하여 취급중의 화물의 손상방지를 행하였다.

• International Journal of Advanced Culture Technology
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• 제10권4호
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• pp.518-528
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• 2022

Virtual Reality (VR) has been widely used in various applications to generate realistic virtual environments. A sense of immersion can be increased by providing additional stimuli such as tactile sensation to VR contents. However, it is still challenging to provide a realistic feel for the wind blowing over the whole body by smoothly controlling the airflow. To address this issue, we employ a household electric fan as a wind generating device to provide users with wind experience in VR environments. The wind generating device targets the whole body to mimic the wind we feel outside in our daily life. To do so, we present a low-cost method to smoothly control household fan speed using an Arduino microcontroller. Here, we use the Sinusoidal Pulse Width Modulation (SPWM) technique to generate the sinusoidal voltage required to drive the fan motor. Our experimental results show how Variable Voltage Variable Frequency (VVVF) is implemented at a low cost using our method for household fan speed control. The results can be applied to various VR applications to enhance the sense of immersion by providing users with realistic wind.

• 품질경영학회지
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• 제35권4호
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• pp.147-158
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• 2007

Owing to the rapid growth in automated manufacturing systems, screening inspection becomes an attractive practice for removing nonconforming items, and it has been suggested that inspection will essentially become an inherent part of modem manufacturing processes. In this paper, we propose rectifying screening inspections which allow quality practitioners to use performance and surrogate variables interchangeably in real-time applications. Two screening inspections are considered; a statistically-based screening inspection to reduce the current proportion of nonconforming items to a specified AOQ(average outgoing quality) after screening, and an economically-based screening inspection where the tolerance limit is determined so that the expected total cost is minimized. It is assumed that the performance variable and the surrogate variable are jointly normally distributed. For two screening inspections, methods of finding the optimal solutions are presented and numerical examples are also given.

• 소음진동
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• 제9권1호
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• pp.121-130
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• 1999

Generally, A Dynamic Absorber by using Active viscous Damping is highlighted for effective suspension system, such as improved ride comfort and handling in the market. Lately, this system based on the Sky-Hook damper theory is introduced by the name of "Active Dynamic Absorber" to us. This system has an excellent performance in contrast to Passive. Adaptive Dynamic Absorber, besides having low cost components of system, low energy consumption. light weight of system. In this viewpoint. most of car-maker will adopt this system in the near future. For this reason, we developed Dynamic Absorber by using Active viscous Damping which is equipped with continuously variable Dynamic Absorber and Control logic consisting Filter and Estimator. control apparatus of Dynamic Absorber operated by 16-bit microprocessor of high performance. variable device of viscous Damping. G-sensor so on. In this paper. several important points of development procedure for realizing this system will be described with results in which is obtained from experiment by simulation and Full car test in Proving ground. respectively.pectively.