• Korean Journal of Food Science and Technology
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• v.18 no.6
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• pp.427-430
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• 1986

Ionizing irradiation and E.O were used for sterilization of 5 different types of spices and mixed spices, and then each treated sample was evaluated using rank-order test to compare the sensory quality of the E.O fumigated sample to that of the irradiated sample. Preference of tested samples was in the descending order of control, the irradiated and the fumigated samples. According to the results of analysis of variance. 5 spices were significantly different at the 1% (P<0.01) or 5% (P<0.05), while mixed spices showed no significance. The results of Duncan's multiple range test showed that there was no significance difference between control and the irradiated sample, while the E.O fumigated sample was significantly different from control and irradiated samples. In conclusion, no adverse effects was found in quality of spices by ionizing radiation for sterilization, but the E.O fumigated sample showed deterioration of quality. The results were corresponded with the changes in major physicochemical components of each sample.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.1
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• pp.58-66
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• 2020

Objectives: The objective of this study was to develop formaldehyde samples for quality control (QC) and to test the applicability of proficiency analytical testing in Korea. Methods: We made formaldehyde samples with certified standard solutions (formaldehyde in water or acetonitrile) and 2,4-dinitrophenylhydrazine (2,4-DNPH)-coated silicagel tubes. Four levels of formaldehyde concentration were tested for storage stability at room temperature and at 4℃ over three months. Analytical proficiency testing was performed with four or 36 institutes. Results: Formaldehyde sample tubes were easily made through the injection of standard solutions and the average efficiencies of recovery were 95-101%. The coefficients of variation (CV) of the formaldehyde samples were 1.39-2.55%. The recovery efficiencies fell between 90% and 110% at the concentration range of 1-10 ㎍/sample over three months storage at refrigerated and room temperature. The CVs were less than 5% in the proficiency analytical testing. By adjusted proficient ranges, 64% of the results of the second proficiency analytical testing were acceptable. Conclusions: The formaldehyde samples made by injection on 2,4-DNPH-coated silicagel tubes were stable and applicable for quality control.

• Journal of Korean Society for Quality Management
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• v.33 no.4
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• pp.117-122
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• 2005

Variable sampling rate(VSR) scheme varies the sampling rate for the current sample depending on the previous value of the control statistic. In this paper, we propose EWMA control charts with variable parameter(VP) scheme, which allows both the sample rate(the sample size or the sampling interval) and the weight to vary. We investigate the effectiveness of the VP scheme relative to the fixed parameter(FP) scheme and the VSR scheme in EWMA control charts. It is shown that using the VP scheme gives some improvements to the ability in detecting small and moderate shifts in the process normal mean.

• Journal of Korean Society for Quality Management
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• v.14 no.2
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• pp.2-8
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• 1986

This thesis is concerned with the design of control chart based on the sample median which is easy to use in practical situations and to analyze the properties for non-normally distributed Weibull process. In this cases are use to the quality characteristics of the process are not normally distributed but skewed due to the intermitted production, small lot size and sample size is small one n=3 or n=5, etc. And when it relates unsymmetrically distributed process, model designed median control chart is more effective than Shewhart $\bar{x}$-chart which assumed on normal distribution, when we exactly should be known Weibull distribution or estimated. The median control chart in this thesis is more robustness compared with other conventionally developed control chart.

• Journal of Korean Society for Quality Management
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• v.21 no.2
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• pp.17-26
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• 1993

Process fault diagnosis is a complicated matter because quality control problems can result from a variety of causes. These causes include problems with electrical components, mechanical components, human errors, job justification errors, and air conditioning influences. In order to make the system run smoothly with minimum delay, it is necessary to suggest heuristic remedies for the detected faults. Hence, this paper describes a heuristic methodology of fault diagnosis that is performed using statistical patterns generated by quality characteristics The proposed methodology is described briefly as follows: If a sample pattern generated by random variables is similar to the number of prototype patterns, the sample pattern may be matched by any prototype pattern among them to be resembled. This concept is based on the similarity between a sample pattern and the matched prototype pattern. The similarity is calculated as the weighted average of squared deviation, which is expressed as the difference between the relative values of standard normal distribution to be transformed by the observed values of quality characteristics in a sample pattern and the critical values of the corresponding ones in a matched prototype pattern.

• Proceedings of the Korean Statistical Society Conference
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• 2003.10a
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• pp.53-58
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• 2003

최근 경제 사회의 급속한 발전에 따라 개인의 활동분야가 다양해지고 개인비밀보호 인식이 커지면서 응답자들이 통계조사에 잘 협조하지 않는 경우가 늘어나고 있다. 따라서 대부분의 통계를 현장조사에 의존하여 생산하고 있는 통계청에서는 현장조사 결과물의 품질상태에 좀 더 관심을 가져야만 하게 되었다. 이러한 현장조사에 대한 풀질관리의 일환으로 현재 통계청에서는 통계별 조사대상으로부터 품질관리표본(Quality Control Sample)을 추출하고 이를 대상으로 리인터뷰를 실시함으로써 응답오차측정, 조사현장의 실터파악, 응답자 의견수렴 등에 활용하고 있다. 리인터뷰는 조사직원의 고의적인 자료조작 또는 보충교육 필요성 등 현장조사업무를 평가하거나 응답분산(simple response variation), 응답편의(response bias) 등을 산출하고, 이를 분석하는 모델을 이용하여 응답결과의 신뢰도를 분석하는데 목적을 두고 있다. 본 연구에서는 품질관리표본(QC Sample) 설계 및 추출, 리인터뷰 시나리오개발, CATI(Computer Assisted Telephone Interviewing)를 이용한 리인터뷰 기법 등을 통계청 사업체조사 모니터링 사례를 중심으로 설명하고 조사직원 특성별 응답오차 측정 및 비교, 정확성 항목에 대한 차이분석 등 격과에 대하여 논하고자 한다.

• Journal of Korean Society for Quality Management
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• v.26 no.3
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• pp.31-45
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• 1998

This paper proposes a method of designing one-sided cumulative scored control charts to control the process mean with a normally distributed quality characteristic. The average run length(ARL) is obtained from the average sample number of sequential probability ratio test(SPRT) on trinomial distribution. Using the analogy between cumulative scored control chart and SPRT for trinomial observations, a procedure is presented to determine three control chart parameters; lower and u, pp.r scoring boundaries and action limit. The parameters are determined by minimizing the ARL when the process is out of control with prespecified ARL when the process is in control.

• Journal of Korean Society for Quality Management
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• v.33 no.3
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• pp.149-155
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• 2005

Cusum control chart is used for the purpose of controling the process mean. We consider the problem related to cusum chart for controling process variance. Previous researches have considered the same problem. The main difficulty shown in the related researches was to derive the ARL function which characterizes the properties of the chart. Sample variance, differently with sample mean, follows chi-squared type distribution, even when the quality characteristics are assumed to be normally distributed. The ARL function of cusum is described by a type of integral equation. Since the solution of the integral equation for non-normal distribution is not known well, people used simulation method instead of solving the integral equation directly, or approximation method by taking logarithm of the sample variance. Recently a new method to solve the integral equation for Erlang distribution was published. Here we consider the steps to apply the solution to the problem of controling process variance.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.04a
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• pp.135-141
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• 2006

Cusum control chart is used for the purpose of controling the process mean. We consider the problem related to cusum chart for controling process variance. Previous researches have considered the same problem. The main difficulty shown in the related researches was to derive the ARL function which characterizes the properties of the chart. Sample variance, differently with sample mean, follows chi-squared type distribution, even when the quality characteristics are assumed to be normally distributed. The ARL function of cusum is described by a type of integral equation. Since the solution of the integral equation for non-normal distribution is not known well, people used simulation method instead of solving the integral equation directly, or approximation method by taking logarithm of the sample variance. Recently a new method to solve the integral equation for Erlang distribution was published. Here we consider the steps to apply the solution to the problem of controling process variance.

• Korean journal of food and cookery science
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• v.24 no.4
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• pp.487-493
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• 2008

This study examined barley sprout powder on the quality and preservation of Sulgidduk. An optimized formulation (moisture 18.2%, barley sprout powder 2.0% and sugar 14.8%) was first obtained, and then the affect if incorporating the barley sprout powder as a raw ingredients in the mixture was evaluated in terms of Sulgidduk shelf life and quality. For comparison, a control Sulgidduk sample was prepared using the optimized formulation exclusive of the barley sprout powder. After preparation the samples were stored for 3 days at $20{\pm}1^{\circ}C$. The moisture contents of both samples slightly decreased during storage: however there was no significant difference between the samples. Both samples had decreases in colorimetric L- and a-value attributable to the addition of the barley sprout powder as well as storage. Furthermore the treatment sample had increases in yellowness due to the addition of barley sprout powder and storage while the control sample had decreases in yellowness throughout the storage period. The treatment sample had increasing textural hardness, gumminess, and chewiness as the storage period increased. Finally, the treatment sample had a higher total microbial count for aerobes at the beginning of storage: however, as the storage period progressed the control had greater microbial levels. In conclusion the overall results indicate the addition of barley sprout powder has a preservaion effect on Sulgidduk. This data is expected to contribute to the commercialization of high-quality Sulgidduk products with added nutrition and extended shelf life.