• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6C
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• pp.251-258
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• 2011

Steel pipe piles have been used as various deep foundation materials for a long time. Recent increase in steel material cost has made engineers reluctant in using it even with its good quality and ease of construction. Therefore when constructing with steel pipe pile, the decision to reuse the excessive pile length that is cut off from the designed pile head elevation after pile driving can be cost saving. This has caused many constructors to reuse the pile leftovers with new piles, but the absence of quantitative structural capacity behaviors of steel pipe pile after pile driving or appropriate countermeasures and standards in reusing steel pipe pile has resulted in wrong applications, pile structural integrity problems, inappropriate limitation of reusable pile length, etc. The structural performance analysis between a new pile and a pile that has undergone working state and ultimate state stress level during pile driving was performed in this research by means of comparing the results between the dynamic pile load test, tensile load test, charpy energy test and fatigue test for high strength steel of $440N/mm^2$ yield strength. Test results show that under working load conditions the yield strength variation is less than 2% and for ultimate load conditions the variation is less than 5% for maximum total blow count of 3000. The results have been statistically analyzed to check the sensitivity of each factors involved. From the test results, reusability of steel pipe pile lies not in the main pipe yield strength deviation but in the reduction of absorb energy, strength changes and quality control at the welded section, shape deformation and local buckling during pile driving.

• International Journal of Highway Engineering
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• v.8 no.4 s.30
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• pp.125-133
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• 2006

In this study, the Korean Industrial Standard(KS) penetration grade system was examined to evaluate its statistical validity. It was found from this limited study that the system has no gap between each grade, the binder falling out of limit trespasses into other binder grade. Therefore, many products can have similar property level with an adjacent grade even though the mean value is within the specification limit. It was also found out that the equal range setup of each grade, such as 20 for 40-60, 60-80, 80-100, has no statistical foundation. Since KS penetration grade is defined without gap between each grade, the producer must maintain the coefficient of variation below the level by the ASTM system to satisfy the normal quality control limit of products. Due to its lack of a gap between grades, higher percentage of products will be duplicated even if the mean is at the median of the specification limits due to material's quality uncertainty. Especially if the mean moves toward the upper limit, a half or more of the binder grade will be overlapped with the upper binder grade. Therefore, KS penetration specification should be immediately modified by statistically valid methodologies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7A
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• pp.649-658
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• 2006

Recently, Software Development was applied to new-approach methods as a various form : client-server system and web-programing, object-orient concept, distributed development with a network environments. On the other hand, it be concerned about the distributed development technology and increasing of object-oriented methodology. These technology is spread out the software quality and improve of software production, reduction of the software develop working. Futures, we considered about the distributed software development technique with a many workstation. In this paper, we discussed optimal release problem based on a stochastic differential equation model for the distributed Software development environments. In the past, the software reliability applied to quality a rough guess with a software development process and approach by the estimation of reliability for a test progress. But, in this paper, we decided to optimal release times two method: first, SRGM with an error counting model in fault detection phase by NHPP. Second, fault detection is change of continuous random variable by SDE(stochastic differential equation). Here, we decide to optimal release time as a minimum cost form the detected failure data and debugging fault data during the system test phase and operational phase. Especially, we discussed to limitation of reliability considering of total software cost probability distribution.

• Journal of Korean Society of Transportation
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• v.23 no.1
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• pp.45-54
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• 2005

The main purpose of this study is located at developing Ominibus Monitoring System(OMS) for the purpose of the internal management, which enable to establish job standards, find out matters to be improved, and appreciate for its treatment in a systematic way. It is through developing subjective or objective estimation tool with use of importance, perceived level, and complex index at international airport by each principal service items, The direction of this study came towards for the purpose of developing a metric analysis tool, utilizing the Quantitative Secondary Data, Analysing Perceived Data through airport user surveys, systemizing the data collection-input-analysis process, making data image according to the graph of results, planning service encounter and endowing control attribution, and ensuring competitiveness at the minimal international standards. It is much important to set up a pre-investigation plan on the base of existent foreign literature and actual inspection to international airport. Two tasks have been executed together on the base of this pre-investigation; one is developing subjective estimation standards for departing party, entering party, and airport residence and the other is developing objective standards as complementary methods. The study has processed for the monitoring services at airports regularly and irregularly through developing software system for operating standards after ensuring credibility and feasibility of estimation standards with substantial and statistical way.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.213-213
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• 2016

수문조사기기의 검정은 수문조사에 활용할 기기를 일관되고 표준화된 기준으로 검사하여 수문조사에 적합한 기기인지 확인하는 것이다. 이러한 검정은 국가수문자료의 신뢰도를 높이고 유지하는 기본적이고 중요한 업무이다. 검정대상기기는 강수량측정기기, 유속측정기기, 수위측정기기, 부유사측정기기, 토양수분측정기기, 증발산량측정기기로 총 6가지이며, 2009년부터 국토교통부 위탁사업으로 한국건설기술연구원(유량조사사업단)에서 수행하고 있다. 특히 유량조사사업단에서는 유속측정기기를 제외한 나머지 5개 수문조사기기에 대해 검정을 수행하고 있다. 연도별로 2009년부터 2015년까지 98대, 334대, 572대, 539대, 359대, 682대, 690대로 총 3,274대를 검정하였고, 관측기종별로 강수량 1,579대, 수위 1,589대 부유사 23대, 토양수분 33대, 증발산량 50대이다. 신청기관별로는 국토교통부(홍수통제소) 1,847대, 환경부(국립환경과학원) 4대, 한국건설기술연구원(유량조사사업단 포함) 81대, K-water 338대, 한국수력원자력(주) 91대, 일반업체 913대에 대한 검정을 실시하였다. 검정을 실시한 강수량측정기기 1,579대 중 보정없이 합격된 기기는 1,495대, 허용오차기준에 미달되어 보정 실시 후 합격한 기기는 76대이며, 불합격 처리된 기기는 8대이다. 수위측정기기는 합격이 1,586대, 기준에 미달되어 불합격된 기기가 2대로 나타났다. 강수량측정기기의 각 연도대비 통계분석 결과 보정률은 2009년 97대 중 8대(8.2%), 2010년 194대 중 3대(1.5%), 2011년 180대 중 24대(13.3%), 2012년 175대 중 17대(9.7%), 2013년 165대 중 15대(9.1%), 2014년 547대 중 8대(1.5%), 2015년 221대 중 9대(4.1%)로 다소 낮은 수치로 나타났다. 이처럼 보정률이 낮게 나타난 이유는 관할기관의 검정을 위한 유지관리 및 사업자의 사전검사 등을 통해 감소한 것으로 판단되며, 이와 같은 결과는 수문자료의 품질 및 신뢰도 향상으로 이어졌다. 그러나 여전히 선진국에 비해 수문조사기기 검정의 중요성에 대한 인프라 구축이 미흡한 실정이다. 수문조사기기 검정의 선진국이라 할 수 있는 미국의 경우 USGS에서 HIF(Hydrogical Istrumentation Facility)라는 별도 조직을 운영하여 관측기기의 렌탈, 수리, 교정 및 검정, 개발, 교육 등 이러한 작업을 일괄 수행하고 있고 조직 내 자체 시설로 수중펌프 시험소, 자연과 유사한 환경에서 테스트 하는 장소, 대형온도챔버 등을 갖추고 있으며, 이러한 시설을 이용하여 기기의 교정 및 검정, 연구 등을 현장과 비슷한 환경에서 다양한 실험을 통해 검정방법을 비교, 분석하는 것을 볼 수 있다. 현재 우리나라의 수문조사기기는 다양한 방법으로 현장에 설치되어 검정방법의 다양성이 요구된다. 향후 우리나라도 HIF와 같이 다양하고 선진화된 시설과 기술을 개선하고 다각적인 시험 과정을 통해 수준 높은 검정방법체계를 갖추려는 노력이 필요하다.

• Industry Promotion Research
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• v.8 no.1
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• pp.111-117
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• 2023

Sampling inspection methods for quality control have been proposed a lot in the industry. However, the sampling inspection method for reliability, which is a quality over time, has been relatively less presented, and there are not many literatures that are clearly summarized. Therefore, this paper focuses on the reliability conformity test to verify that the reliability evaluation scale value of the target is satisfied during the reliability test. To this end, first, we look at the conditions that both consumers and producers can satisfy in terms of the OC curve and find out what sampling methods satisfy the desired level of producer risk and consumer risk. Next, two methods of the reliability sampling methods such as attribute and variable reliability sampling methods are examined. Specifically, the attribute reliability sampling method is a form of sampling plan where n samples are tested for a certain period of T hours and the lot is accepted if the number of failures is less than or equal to a certain number c. On the other hand, the variable reliability sampling method is a form of sampling plan where the lot is accepted if the reliability evaluation scale such as MTBF satisfies a certain standard. Both sampling plans may also use inspection tables.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.670-676
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• 2017

The purpose of this study is to analyze the shipbuilding structure of Hallabong Tangorover ten-day and monthly intervals, to determine whether the shipment control can stabilize and increase the income of Hallabong Tangor farmers by estimating and analyzing the price flexibility function of Hallabong, and to derive the policy implication. Looking at the overall market, the 1% increase in shipment volume indicates that the coefficient of price flexibility varies with time. The largest decline is in late December and early January. The dummy variable indicating the year in which the quality drops somewhat is statistically significant from March to May, and the average of them is -0.337%. This implies a greater importance for quality control and shipment control when quality is worse than good quality. The price flexibility, which indicates price changes due to 1% increase in monthly shipment volume of Hallabong Tangor, varies with time. The coefficient of price flexibility was the highest at -0.46 in December, but prices fell slightly due to quality improvement and the increase in special demand of New Year's demand, which was -0.33% in January, -0.261% in February, -0.307% in March, and -0.318% in April. Since then, the amount of storage has been gradually exhausted, and the price flexibility has fallen slightly to -0.243% in May and -0.236% in June. DUM02, which represents the year when more than 7 days after the New Year holidays are in February is from February to June (+). This indicates that the price decrease due to increase in volume is less than that in January when the New Year is in February. This indicates a greater necessity for shipment control when New Year holidays are in January.

• Journal of Nutrition and Health
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• v.50 no.3
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• pp.294-301
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• 2017

Purpose: The purposes of this study were to investigate food consumption practices and analyze factors that influence customer satisfaction of an HACCP applied restaurant in a highway service area. Methods: A total of 207 customer responses were used for data analysis. Statistical analyses were conducted using the SPSS program (ver. 22.0) for $x^2$-test, Pearson correlation analysis, and multiple regression analysis. Results: Reasons for visiting the highway area were using the restroom (86.0%), purchasing of meals or snacks (70.1%), taking a rest (58.5%), and shopping (3.4%) and selection attributes of food sold in the highway service area were food taste (48.8%), food safety (33.3%), and waiting time for meal (10.7%). According to the results of the survey, udon (66.2%) was the most preferred meal, followed by instant noodles (56.0%), kimbap (50.7%), pork cutlet (38.2%), and bibimbap (29.0%). In addition, coffee (73.4%) was the most preferred among snacks and beverages, followed by beverages (58.9%), walnut cake (53.1%), mineral water (52.2%), and hotbar (52.2%). Satisfaction evaluation scores of foods sold in the highway service area were highest for appropriate portion size, followed by food safety, menu variety, food taste, and reasonable price. Overall customer satisfaction scores regarding the restaurant in the highway service area was 3.24 out of 5 points on average. According to the results of the multiple regressing analysis, food taste (p < 0.001) and reasonable price (p < 0.01) had significant positive effects on overall customer satisfaction. Conclusion: To enhance customer satisfaction, restaurant managers in the highway service area should implement HACCP, improve food taste, and set up a proper price for food sold at the restaurant in the highway service area.

• Korean Journal of Construction Engineering and Management
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• v.23 no.2
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• pp.16-23
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• 2022

This study examined the trend of international competitiveness over the past 10 years (2011-2020), focusing on comparative analysis with China and the United States, targeting seven major export items of Korean construction machinery based on 6 units of HS code. To this end, the export similarity index and trade competitiveness index were calculated and analyzed using UN Comtrade and Korea International Trade Association trade statistics. As a result of the analysis, competition between Korea and China has intensified over the past decade, and competition with the United States has remained at a certain level. Korean forklifts (8427.20) are exporting to the world with strong competitiveness in the global market. Excavators (8429.52) and loaders (8429.51), which have the largest export share of Korean construction machinery, have a weight advantage, but they are exporting due to price inferiority. The rest of the items were found to be inferior in price and weight, and were not competitive in the global market. These analysis results suggest the following implications. First, it is necessary to strengthen efforts to expand exports of universal construction machinery items, which are expected to increase in demand in the future, by boosting the economy and expanding infrastructure investment in accordance with eco-friendly policies. Second, excavators, which have been shown to have a quality advantage and a price competitive advantage, need to further strengthen export marketing activities not only in China and the United States but also in emerging developing countries.

• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.111-120
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• 2011

A purpose of study is to develop optimization and radiation dose exposure reference level by measuring actual radiation dose in condition of quality control of mammography equipment for 39 clinics. The result were as follows. First, we measured T-test separating radiology from general clinic. According to the test, mAs was measured at average 78.58 mAs; radiology at 80.16 mAs and general clinic at 77.22 mAs. And, kerma rate was measured at average 7.71 mGy/mR; radiology at 8.94 mGy/mR and general clinic at 6.66 mGy/mR. HVL was measured at average 0.42 mmAl; radiology at 0.40 mmAl and general clinic at 0.43 mmAl. Average glandular dose was measured at average 1.14 mGy; radiology at 1.09 mGy and general clinic at 1.19 mGy. Second, we measured value of mAs, HVL, processing method and so on dividing two groups. And, we compared and analyzed average value measured using T-test. As a result, there was significance level in SID(P<0.05). There was significance level in mAs(P<0.05). Because processor was measured at 1.00 mGy and CR at 1.17 mGy according to the processing method of radiology. Third, according to the correlation analysis, radiology had significance level between average glandular dose and mAs and general clinic had significance level between average glandular dose and SID(P<0.05). Forth, as a result of regression analysis, mAs affected 22.7%t of average glandular dose and SID affected 21.7% of average glandular dose, which had significance level(P<0.05). And, mAs affected 29.0% of average glandular dose in radiology and SID affected 29.1% of average glandular dose in general clinic, which was most influential.