• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.311-314
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• 2004

Toxicity test fur various synthetic lubricant oil bases derived from biodiesel was carried out. The earthworms(Eisenia fetida) were maintanied in artificial soil consisting of sand for 14 days. Eisenia fetida was cultivated at temperature of $20{\pm}2^{\circ}C$, pH 6.0 $\pm$ 0.5 and moisture of $31\~37\%$. Pentaerythritol(PE) lubricant oil base was tested for acute toxicities to Eisenia fetida. The earthworms were exposed to each lubricant oil with various concentrations of lubricant oil base. After 14 days, the number of surviving earthworms and thier weight alteration during the test period was determined. $LC_{50}$(lethal concentration when $50\%$ of the population were killed) pentaerythritol was determined to be 1,555 mg/kg soil dry weight.

• Journal of Environmental Science International
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• v.28 no.11
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• pp.1041-1045
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• 2019

In this study, the KS A ISO Guide 35 was applied to develop analytical standards for heavy metal cadmium using the Korean mussel (Mytilus coruscus) and to evaluate the homogeneity and stability of the sample. Some of the crucial characteristics that reference materials must consist include homogeneity and stability of both intra- and inter-bottles. We tested homogeneity using ANOVA analysis and short-term stability using regression analysis. The variations of cadmium concentrations did not significantly differ between intra- and inter-bottles (F=0.41, p=0.90). For short-term stability verification, cadmium analysis results were not statistically significant as a result of the regression analysis (significance F=0.51, p=0.53). This suggests that we can not dismiss the null hypothesis that there is no significant variation in concentrations of cadmium over time. These results indicated that the cryogenic-milling process has statistically proven the short-term stability for materials from mussels in the chemical analysis of cadmium. Therefore, we propose that the Korean mussel's reference material developed for the proficiency test could be used as a tool to evaluate reliability and consistency in laboratories.

• Journal of the Korean Society of Safety
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• v.27 no.2
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• pp.111-116
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• 2012

This study deals with the traffic accidents of circular intersections in Korea. The purposes are to comparatively analyze the characteristics by operational type, and to develop the models using the data of 82 intersections. In pursuing the above, this study gives particular emphasis to modeling such the accidents as the roundabout and rotary in urban area. The main results analyzed are as follows. First, the null hypotheses that the number of accidents are the same in both the urban and rural intersections, and roundabout and rotary in urban area, were analyzed to be rejected. Second, 3 accident models were developed, which were all statistically significant. The independent variables used in the above models are the ADT, number of approach lane, bus stop, parking facilities, and others. This study could be expected to give some implications to the traffic safety policy decision-making.

• Communications for Statistical Applications and Methods
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• v.5 no.2
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• pp.517-529
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• 1998

When the sample size is small the robust minimum Hellinger distance (HD) estimator can have substantially poor relative efficiency at the true model. Similarly, approximating the exact null distributions of the ordinary Hellinger distance tests with the limiting chi-square distributions can be quite inappropriate in small samples. To overcome these problems Harris and Basu (1994) and Basu et at. (1996) recommended using a modified HD called penalized Hellinger distance (PHD). Lindsay (1994) and Basu et al. (1997) showed that another density based distance, namely the negative exponential disparity (NED), is a major competitor to the Hellinger distance in producing an asymptotically fully efficient and robust estimator. In this paper we investigate the small sample performance of the estimates and tests based on the NED and penalized NED (PNED). Our results indicate that, in the settings considered here, the NED, unlike the HD, produces estimators that perform very well in small samples and penalizing the NED does not help. However, in testing of hypotheses, the deviance test based on a PNED appears to achieve the best small-sample level compared to tests based on the NED, HD and PHD.

• The Korean Journal of Food And Nutrition
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• v.26 no.4
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• pp.990-995
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• 2013

In the pursuit of practical usage for Codonopsis lanceolata and development of functional processed food material, the research on the product characterization is being performed through the manufacturing of Yanggaeng which is extracted from the Codonopsis lanceolata skin concentrate. By adding Codonopsis lanceolata skin extracts (0, 40, 60, 80, 100%) to the product, the chemical property characterization and organoleptic test of the produced Yanggaeng are being conducted. The scavenging effects on DPPH free radical have a significant proportional relationship with the addition of Codonopsis lanceolata skin extracts as 61.30 for 100% added group as compared with 52.72 for the null-addition group. It is considered that the antioxidative activity increases with the addition of the Codonopsis lanceolata skin extraction as the SOD similar activity rate was increased to 49.23% from 39.31%, the flavor preference was ranked as 80%>60%>0%>100%>40% showing that 60~80% of Codonopsis lanceolata skin extraction addition seems to be the proper amount.

• Journal of the Korean Society of Safety
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• v.33 no.1
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• pp.142-147
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• 2018

This study aims to analyze and discuss the accidents based on the level of traffic culture (LOT). In pursuing the above, LOT are divided into three categories based on the standardized index of traffic culture. Also, this study focuses on developing the accident models using GLM (generalized linear model). The main results are as follows. First, the null hypotheses that the ratios of fatal and serious injured persons (FSI) are the same over categories are rejected. Second, as the common variables, the ratio of turn signal usage and elderly population are analysed to be impacted to the ratio of FSI. Third, the traffic culture indicators among 5 accident factors which give impact to 'high level' are judged to affect the reduction of FSI. Fourth, compared to other levels, the traffic law violations among 7 accident factors of 'medium level' are estimated to influence the increase of FSI. Finally, in 'low level', the increasing ratio of traffic culture index compared to that of previous year and the number of hospital beds per person are evaluated to be significant to reducing the ratio of FSI. This study can be expected to give some policy implications to regional traffic safety policy-making.

• Design & Manufacturing
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• v.13 no.4
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• pp.51-56
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• 2019

Due to industrial development, the importance of GD&T tolerance is growing day by day. Roundness measurement means the size deviated from the ideal circle. Roundness evaluation methods include LSCI, MZCI, MCCI, and MICI. Generally, A is used a lot at industrial evaluation. In this experiment, we studied the variations in table velocity, filter values, and detector angles, which can cause errors in roundness measurements. The measurement conditions were table speeds of 10, 30 and 60 mm/s, probe angles of 10, 20 and 30 degrees and frequency filter settings of 15, 150 and 500 upr and The number of experiments was measured 30 and the average value was chosen as a representative value. The hypothesis test showed that the p-value for the frequency filter was greater than 0.05, and the experiment rejected the null hypothesis and adopted the alternative hypothesis.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.468-476
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• 2008

This paper presents a novel approach to economic dispatch (ED) with nonconvex fuel cost function as combinatorial optimization problems (COP) while most of the conventional researches have been developed as function optimization problems (FOP). One nonconvex fuel cost function can be divided into several convex fuel cost functions, and each convex function can be regarded as a generation type (G-type). In that case, ED with nonconvex fuel cost function can be considered as COP finding the best case among all feasible combinations of G-types. In this paper, a genetic algorithm is applied to solve the COP, and the $\lambda$-P table method is used to calculate ED for the fitness function of GA. The $\lambda$-P table method is reviewed briefly and the GA procedure for COP is explained in detail. This paper deals with three kinds of ED problems, namely ED considering valve-point effects (EDVP), ED with multiple fuel units (EDMF), and ED with prohibited operating zones (EDPOZ). The proposed method is tested for all three ED problems, and the test results show an improvement in solution cost compared to the results obtained from conventional algorithms.

• Journal of the Korea Safety Management & Science
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• v.15 no.1
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• pp.283-292
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• 2013

This paper aims to propose a new steps of hypothesis testing using analysis process and improvement process in the six sigma DMAIC. The six sigma implementation models proposed in this paper consist of six steps. The first step is to establish a research hypothesis by specification directionality and FBP(Falsibility By Popper). The second step is to translate the research hypothesis such as RHAT(Research Hypothesis Absent Type) and RHPT(Research Hypothesis Present Type) into statistical hypothesis such as $H_0$(Null Hypothesis) and $H_1$(Alternative Hypothesis). The third step is to implement statistical hypothesis testing by PBC(Proof By Contradiction) and proper sample size. The fourth step is to interpret the result of statistical hypothesis test. The fifth step is to establish the best conditions of product and process conditions by experimental optimization and interval estimation. The sixth step is to draw a conclusion by considering practical significance and statistical significance. Important for both quality practitioners and academicians, case analysis on six sigma projects with implementation guidelines are provided.

• Journal of the Korean Society of Safety
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• v.33 no.4
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• pp.105-110
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• 2018

Korea has entered to 'aged society', which the elderly people over 65 years old is over 14% of total population. This paper aims to analyze the traffic accident by aging level. In pursuing the above, this paper focuses on modeling the traffic accident severity based on three aging levels. The main results are as follows. First, the ratio of fatal and serious injured persons (FSI) is judged to increase according to increasing aging level. Second, the null hypothesis that there is no difference in FSI among three aging levels (aging, aged, and super-aged) is rejected. Four accident severity generalized linear models which are all statistically significant have been developed. Third, the common variables are analyzed to be median age, the number of hospital beds per persons, and turn signal usage ratio. Fourth, the differentiated traffic safety policies fitted to aging levels are required. The enforcement of traffic law violation and safety enhancement of motorcycle in the region of 'aging society', improvement of traffic facilities in the region of 'aged society', and expansion of transportation facilities in the region of 'super-aged society' are evaluated to be indispensable.