• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.1
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• pp.79-84
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• 2003

종래의 연구들은 주로 시간이 경과함에 따라 수리비용과 고장시간 간격이 고정된 상태에서 최적교환시각(T)을 구하는 조건을 발견하는데 중점을 두었으나, 대부분의 시스템은 시간이 경과할수록 고장시간간격이 좁아지고 수리비용은 증가하는 것이 일반적이다. 본 논문에서는 위의 두 조건을 만족하는 보다 현실적인 모델을 구축하였으며, 또 일정시간 내에 2개의 시스템이 존재할 때 어느 조건 하에서 시스템이 확률적으로 우월한가를 분석하는 연구를 수행하였다. 즉, 시스템은 시간이 경과함에 따라 확률 P［N=k］로서 완전수리를, 1-P［N=k］로서 소수리를 행하는 모델을 고려하였다. 여기서 N은 연속된 완전수리 사이의 소수리의 수를 나타낸다. 또한 초기고장에 있어서 수리에 의해 새로운 시스템이 되는 확률이 높고, 고장횟수가 증가함에 따라 완전수리가 행해지는 확률이 낮아지는, 보다 현실에 가까운 모델을 구축하였다. 모델을 일반화하기 위해 수리비용은 확률변수로 가정하였다.

• The Journal of Korea Robotics Society
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• v.6 no.3
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• pp.255-262
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• 2011

Many intelligent robots have to be given environmental information to perform tasks. In this paper an intelligent robot, that is, a cleaning robot used a sensor fusing method of two sensors: LRF and StarGazer, and then was able to obtain the information. Throughout wall following using laser displacement sensor, LRF, the working area is built during the robot turn one cycle around the area. After the process of wall following, a path planning which is able to execute the work effectively is established using flow network algorithm. This paper describes an algorithm for minimal turning complete coverage path planning for intelligent robots. This algorithm divides the whole working area by cellular decomposition, and then provides the path planning among the cells employing flow networks. It also provides specific path planning inside each cell guaranteeing the minimal turning of the robots. The proposed algorithm is applied to two different working areas, and verified that it is an optimal path planning method.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.11 no.1
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• pp.1-12
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• 1985

A strain of Pseudomonas aeruginosa was isolated from the spoiled product and its characteristics on various formaldehyde-releasing preservatives were investigated. This strain, P. aeruginosa FR, could utilize 1.0% of imidazolidinyl urea and 0.2% of DMDM hydantoin as a sole carbon and nitrogen source in the minimal salts medium. With the growth of the strain in minimal salts medium containing imidazolidinyl urea, formic acid was initially accumulated according to the decrease of formaldehyde concentration. It was suggested that formaldehyde dehydrogenase was involved in this oxidation process and could catalyze formaldehyde, imidazolidinyl urea, DMDM hydantoin and quaternium-15, but not bronopol. MICs of this strain to each preservation were 0.03% in formaldehyde, 1.0% in imidazolidinyl urea, 0.2% in DMDM hydantoin, 0.2% in quaternium-15 and 0.1% of EDTA-2Na. But the MICs were diminished about ten times when 0.01% of EDTA-2Na was added to the preservative systems. In actual challenge test, the eyeliner and the pack which contained paraben and imidazolidinyl urea were not able to be protected from this strain, but when 0.05% EDTA-2Na was added the products were sufficiently preserved.

• Journal of the Korean Mathematical Society
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• v.46 no.5
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• pp.1027-1040
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• 2009

A ring R is called IFP, due to Bell, if ab = 0 implies aRb = 0 for a, b $\in$ R. Huh et al. showed that the IFP condition is not preserved by polynomial ring extensions. In this note we concentrate on a generalized condition of the IFPness that can be lifted up to polynomial rings, introducing the concept of quasi-IFP rings. The structure of quasi-IFP rings will be studied, characterizing quasi-IFP rings via minimal strongly prime ideals. The connections between quasi-IFP rings and related concepts are also observed in various situations, constructing necessary examples in the process. The structure of minimal noncommutative (quasi-)IFP rings is also observed.

• Journal of the Optical Society of Korea
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• v.7 no.3
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• pp.160-164
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• 2003

Materials processing by ultrashort pulsed laser is actively being applied to micromachining technology due to its advantages with regard to non-thermal machining. In this study, materials processing with ultrashort pulses was studied by using the high repetition rate of a 800 nm Ti:sapphire regenerative amplifier. This revealed that the highly precise micromachining of metallic thin film and bulk glass with a minimal heat affected zone (HAZ) could be obtained by using near damage threshold energy. Grooves with diffraction limited sub-micrometer width were obtained with widths of 620 nm on Cr thin film and 800 nm on a soda-lime glass substrate. The machined patterns were investigated through SEM images. We also phenomenologically examined the influence of variations of parameters and proposed the optimal process conditions for microfabrication.

• International Journal of Quality Innovation
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• v.5 no.1
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• pp.1-9
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• 2004

The nonhomogeneous poisson process (NHPP) is often used to model repairable systems that are subject to a minimal repair strategy, with negligible repair times. In this situation, the system can be characterized by its intensity function. There have been many NHPP models according to intensity functions. However, the intensity function of system in use can be changed because of repair or its aging. We consider the single change point model as the modification of the power law process. The shape parameter of its intensity function is changed before and after the change point. We detect the presence of the change point using Bayesian methodology. Some numerical results are also presented.

• Communications for Statistical Applications and Methods
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• v.25 no.5
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• pp.453-470
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• 2018

We study how to distinguish the parameters of the sparse autoregressive (AR) process from zero using a non-convex penalized estimation. A class of non-convex penalties are considered that include the smoothly clipped absolute deviation and minimax concave penalties as special examples. We prove that the penalized estimators achieve some standard theoretical properties such as weak and strong oracle properties which have been proved in sparse linear regression framework. The results hold when the maximal order of the AR process increases to infinity and the minimal size of true non-zero parameters decreases toward zero as the sample size increases. Further, we construct a practical method to select tuning parameters using generalized information criterion, of which the minimizer asymptotically recovers the best theoretical non-penalized estimator of the sparse AR process. Simulation studies are given to confirm the theoretical results.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.814-818
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• 1997

The chemical waste treatment, APEG (alkali/polyethylene glycol) process has been shown to be effective for the dechlorination of PCBs in transformer oil. Considerable amount of PCBs, however, still remains in the waste exceeding the 25-50 ppm limit set by regulatory agency. A new thermal regeneration technology has been developed in our laboratory for disposal of hazardous organic wastes. Due to the limited oxidation of carbon surface through the reverse movement of flame front to oxidant flow, this technology was termed counterflow oxidative system (COS). Specially, the oxidant flow in the COS process is a principal parameter which determines the optimum conditions regarding acceptable removal and destruction efficiency of adsorbed organic wastes at minimal carbon loss. The COS process, under optimum conditions, was found to be very effective and the removal and destruction efficiency of 99.99% or better was obtained for residual PCBs in the waste while bulk (≥90%) of carbon was recovered. Any toxic formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo furans (PCDFs) were not detected in the regenerated carbon and impinger traps. The results of surface area measurement showed that the adsorptive property of regenerated carbon is mostly reclaimed during the COS process.

• Journal of Pharmacopuncture
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• v.6 no.3
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• pp.87-90
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• 2003

The purpose of this study is to investigate and analyze the selection process of the Science Citation Index(SCI). SCI has been the benchmarking medium of scientific journals for over 40 years by reviewing thousands of journals published each year. The discipline of Traditional Oriental Medicine has been gaining global interest in recent years, yet the number of related journals indexed by SCI has been minimal. Korean Medicine has been producing number of quality journals for decades, but lack of journals in the English language and other problems has hindered consideration for registering with SCI. This paper will focus on the journal selection process at ISI and recommend the criteria needed for a journal to be considered for SCI selection.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.46-52
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• 2000

3D Welding and Milling is a solid freeform fabrication process which is based on the combination of welding as additive and conventional milling as subtractive technique. This hybrid approach enables direct building of metallic parts with high accuracy and surface finish. Although it needs further improvements it shows an application potential in rapid tooling of injection mold inserts as the investigation results show. To optimize the process for higher surface quality and accuracy effectively Taguchi method is applied to the experimental investigation. in this way relationships between process parameters and final product qualities such as tensile strength and surface hardness are found with minimal efforts.