• 품질경영학회지
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• 제34권2호
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• pp.129-135
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• 2006

In the advance of computer technology, it is possible to keep all the related informations for monitoring equipments in control and huge amount of real time manufacturing data in a data base. Thus, the statistical analysis of large data sets with hundreds of thousands observations and hundred of independent variables whose some of values are missing at many observations is needed even though it is a formidable computational task. A tree structured approach to classification is capable of screening important independent variables and their interactions. In a Six Sigma project handling large amount of manufacturing data, one of the goals is to screen vital few variables among trivial many variables. In this paper we have reviewed and summarized CART, C4.5 and CHAID algorithms and proposed a simple method of screening vital few variables by selecting common variables screened by all the three algorithms. Also how to develop a logistics regression model on a large data set is discussed and illustrated through a large finance data set collected by a credit bureau for th purpose of predicting the bankruptcy of the company.

• Nuclear Engineering and Technology
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• 제49권2호
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• pp.349-359
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• 2017

During the past 25 years, in the context of probabilistic safety assessment, efforts have been directed towards establishment of comprehensive pipe failure event databases as a foundation for exploratory research to better understand how to effectively organize a piping reliability analysis task. The focused pipe failure database development efforts have progressed well with the development of piping reliability analysis frameworks that utilize the full body of service experience data, fracture mechanics analysis insights, expert elicitation results that are rolled into an integrated and risk-informed approach to the estimation of piping reliability parameters with full recognition of the embedded uncertainties. The discussion in this paper builds on a major collection of operating experience data (more than 11,000 pipe failure records) and the associated lessons learned from data analysis and data applications spanning three decades. The piping reliability analysis lessons learned have been obtained from the derivation of pipe leak and rupture frequencies for corrosion resistant piping in a raw water environment, loss-of-coolant-accident frequencies given degradation mitigation, high-energy pipe break analysis, moderate-energy pipe break analysis, and numerous plant-specific applications of a statistical piping reliability model framework. Conclusions are presented regarding the feasibility of determining and incorporating aging effects into probabilistic safety assessment models.

• 자원환경지질
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• 제21권1호
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• pp.17-27
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• 1988

The Cretaceous Jinsan gold-bearing hydrothermal veins occur within the Late Proterozoic to Mid Ordovician metasedimentary rocks, intruded by Early Cretaceous pink-feldspar granite($142{\pm}2.0m.y.$). Electrum-galena-sphalerite mineralization was deposited in three stages of quartz and calcite veins. Quartz sulfide-bearing stage I and II evolved from initial high temperatures (near $360^{\circ}C$)to later lower temperatures(near $220^{\circ}C$)from lower salinity fluids(1.0 to 3.2 wt.% NaCl eq.). Fluid inclusion data from the post ore carbonate stage reflects much cooler($110^{\circ}$ to $180^{\circ}C$). Evidence of boiling indicates pressure of<85 bars, corresponding to depths of 400m to 1050m assuming lithostatic and hydrostatic loads. Au-deposition was likely a result of boiling, coupled with declining temperatures. The ${\delta}^{34}S$ $H_2S$ values calculated for sulfides are consistent with an igneous source of sulfur with a ${\delta}^{34}S_{{\Sigma}S}$ value near 4.0‰.

• 한국지반공학회논문집
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• 제16권2호
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• pp.61-70
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• 2000

When clay foundations of embankments are treated with vertical drain, essentially, the strain occurs to vertical direction but the water flow is radial. The initial horizontal permeability and its variation with the vertical compression are key parameters for the choice of the type of drains, their spacing, and affect to the cost of the project. In this study, CRS consolidation test is performed to investigate the anisotropic characteristics of decomposed mudstone soil and direct permeability test is performed on the same specimens. The results of testing show that Ch is larger than Cv. specially, the Cv - $\sigma$v relationship for a soil sample is viewed from three different curve segments corresponding to overconsolidated, transition and normally consolidated states. The anisotropic ratio, rk(kh/kv) is 2.19. Coefficient of permeability in normally consolidated state is related to its void ratio and permeability parameter n. C can be determined from a linear plot of log[k(1+e)] versus log e. The slope, n, of graphs is the same, whereas the vertical intercept, log C, seems to vary somewhat for anisotropic.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권3호
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• pp.167-172
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• 2001

Staphylokinase (SAK) was produced in B. subtilis using two different promoter systems, i.e. the P43 and sacB promoters. To maximize SAK expression in B. subtilis, fermentation control strategies for each promoter were examined. SAK, under P43, a vegetative promoter transcribed mainly by $\sigma$(sup)B containing RNA polymerase, was overexpressed at low dissolved oxygen (D.O.) levels, suggesting that the sigB operon is somewhat affected by the energy charge of the cells. The expression of SAK at the 10% D.O. level was three times higher than that at the 50% D.O. level. In the case of sacB, a sucrose-inducible promoter, sucrose feeding was used to control the induction period and induction strength. Since sucrose is hydrolyzed by two sucrose hydrolyzing enzymes in the cell and culture broth, the control strategy was based on replenishing the loss of sucrose in the culture. With continuous feeding of sucrose, WB700 (pSAKBQ), which contains the SAK gene under sacB promoter, yielded ca. 35% more SAK than the batch culture. These results present efficient promoter-dependent control strategies in B. subtilis host system for foreign protein expression.

• Ocean and Polar Research
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• 제23권2호
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• pp.181-188
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• 2001

We describe here the Korea ocean prediction system that closely resembles operational numerical weather prediction systems. This prediction system will be served for real-time forecasts. The core of the system is a three-dimensional primitive equation numerical circulation model, based on ${\sigma}$-coordinate. Remotely sensed multi-channel sea surface temperature (MCSST) is imposed at the surface. Residual subsurface temperature is assimilated through the relationship between vertical temperature structure function and residual of sea surface height (RSSH) using an optimal interpolation scheme. A unified grid system, named as [K-E-Y], that covers the entire seas around Korea is used. We present and compare hindcasting results during 1990-1999 from a model forced by MCSST without incorporating RSSH data assimilation and the one with both MCSST and RSSH assimilated. The data assimilation is applied only in the East Sea, hence the comparison focuses principally on the mesoscale features prevalent in the East Sea. It is shown that the model with the data assimilation exhibits considerable skill in simulating both the permanent and transient mesoscale features in the East Sea.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.129-138
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• 2003

Rolling bearings are classified one of the most important machine elements. The various function of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required in improve bearing lubrication. Three urea/ether oil greases with identical composition were synthesized to compare the performance of these greases according to the thickener content of grease. The typical grease physical properties were investigated. And life test of these greases was conducted by FE-9 grease life tester. The characteristics of the greases before and after life test were investigated using FT-IR, microscope, OIT and TAN meter. Large differences in the grease performance depending on the content of the thickener were observed. The grease with higher content of the hickener showed higher performance such as long life time and low TAN value. After preliminary test, twelve greases were synthesized and evaluated the performance of dropping point and OIT, then optimized two greases were selected by SSRED (Six Sigma Robust Engineering Design) using dropping point and OIT data. Characteristics of the optimized two greases were on the same level with estimated value. The optimized grease by means of OIT value showed longer grease life in comparison with optimized grease by dropping point. However two greases showed higher performance than typical urea/ether oil.

• 한국전자파학회논문지
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• 제11권4호
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• pp.534-543
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• 2000

본 논문은 광섬유 브래그 격자에서 형성된 굴절율 포락선 분포 변화에 따른 반사 스펙트럼을 컴퓨터 시율레 이션을 통하여 분석하였다. 그 결과는 차세대 광통신 분야에서 다량의 정보를 전송하기 위해 펼요한 DWDM용 FBG 협대역 필터 설계 데이터로 활용 및 응용할 수 있으며, 또한 자외선 영역의 엑시머 레이저를 조사하여 형 성된 광섬유 브래그 격자내에서 굴절율 포락선 분포 변화에 따른 반사 스펙트럼을 컴퓨터 시률레이션 하였다. 광파장 분할 다중 방식용 광섬유 브래그 격자의 협대역 필터를 설계하는데 유용하다. 본 논문은 광섬유 브래그 격자내에 형성환 굴절율 포락선 분포를 갖는 세 가지 유형 첫째 Uniform. 둘째 Gaussia apodized, 셋째 Raised-cosine apodized 에 따른 반사 스펙트럼을 비교 분석하였다.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3607-3617
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• 2012

In this paper, the study of various ortho- and meta-substituted Magnolol derivatives is presented. The reaction enthalpies related to three antioxidant action mechanisms HAT, SET-PT and SPLET for substituted Magnolols have been calculated using DFT/B3LYP method in gas-phase and water. Calculated results show that electron-withdrawing substituents increase the bond dissociation enthalpy (BDE), ionization potential (IP) and oxidation/reduction enthalpy (O/RE), while electron-donating ones cause a rise in the proton dissociation enthalpy (PDE) and proton affinity (PA). In ortho- position, substituents show larger effect on reaction enthalpies than in meta-position. In comparison to gas-phase, water attenuates the substituent effect on all reaction enthalpies. In gas-phase, BDEs are lower than PAs and IPs, i.e. HAT represents the thermodynamically preferred pathway. On the other hand, SPLET mechanism represents the thermodynamically favored process in water. Results show that calculated enthalpies can be successfully correlated with Hammett constants (${\sigma}_m$) of the substituted Magnolols. Furthermore, calculated IP and PA values for substituted Magnolols show linear dependence on the energy of the highest occupied molecular orbital ($E_{HOMO}$).

• 대한안전경영과학회지
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• 제12권3호
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• pp.257-262
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• 2010

The study investigates the various Acceptance Control Charts (ACCs) based on the factors that include process independence, data weighting scheme, subgrouping, and use of control charts. USL - LSL > $6{\sigma}$ that used in the good condition processes in the ACCs are designed by considering user's perspective, producer's perspective and both perspectives. ACCs developed from the research is efficiently applied by using the simple control limit unified with APL (Acceptable Process Level), RLP (Rejectable Process Level), Type I Error $\alpha$, and Type II Error $\beta$. Sampling interval of subgroup examines i.i.d. (Identically and Independent Distributed) or auto-correlated processes. Three types of weight schemes according to the reliability of data include Shewhart, Moving Average(MA) and Exponentially Weighted Moving Average (EWMA) which are considered when designing ACCs. Two types of control charts by the purpose of improvement are also presented. Overall, $\alpha$, $\beta$ and APL for nonconforming proportion and RPL of claim proportion can be designed by practioners who emphasize productivity and claim defense cost.