PURPOSES : Roller-compacted concrete pavement (RCCP) is a superstiff-consistency concrete pavement that exhibits excellent strength development owing to a hydration reaction and interlocking aggregates owing to the roller compaction. A zero-slump concrete mixture is generally used. Hence, it is important to control the consistency of the RCCP mixture to prevent the deterioration of the construction quality (such as material separation during paving). The workability of the RCCP is characterized by its consistency and controlled by the Vebe time, whereas a conventional concrete pavement is controlled based on the slump test. The consistency of the RCCP changes over time after concrete mixing owing to delivery, construction time delays, etc. Thus, it is necessary to use the optimum Vebe time to achieve the best construction quality. Therefore, this study aims to develop a Vebe time prediction model for efficiently controlling the consistency of RCCPs according to random time variations. METHODS : A Vebe time prediction model was developed using a multiple linear regression analysis. A dataset of 131 samples was used to develop the model. The collected data consisted of variables with large potential effects on the consistency of the RCCP, such as the water-cement ratio (W/C), sand/aggregate ratio (S/a), water content (ω), water content per unit volume (W), cement (C), fine aggregate (S), coarse aggregate (G), water reducing admixtrue (PNS), air-entraining admixture (AE), delay time (T), air temperature (TEM), and humidity (HUM). In the multiple linear regression analysis, the mentioned parameters were used as the independent variables, and the Vebe time was the dependent variable. The Vebe time prediction models were evaluated by considering the adjusted R2 and p-values. The selection of the model was based on the largest R2 value and an acceptable p-value (p<0.05). RESULTS : The Vebe time prediction model achieved an adjusted R2 value of 64.14% with a significance level (p-value) of less than 0.05. This shows that the predictive model is adequately described for the dependent variable, and that the model is suitable for Vebe time predictions. Moreover, the significance level of the independent variables is less than 0.05, indicating significant effects on the Vebe time (i.e., the dependent variable). CONCLUSIONS : The Vebe time prediction model developed in this study can be used to estimate Vebe times with an R2 of 63.33% between the measured and predicted values. The proposed Vebe time prediction model is expected to be effectively utilized for the quality control of RCCP mixtures. Moreover, it is expected to contribute to achieving good RCCP construction quality.

Recently, due to the aging of workers and the weakening of the labor base in the automobile industry, research on quality inspection methods through ICT(Information and Communication Technology) convergence is being actively conducted. A lot of research has already been done on the development of an automated system for quality inspection in the manufacturing process using image processing. However, there is a limit to detecting defects occurring in the automotive sunroof sealer application process, which is the subject of this study, only by image processing using a general camera. To solve this problem, this paper proposes a system construction method that collects image information using a infrared thermal imaging camera for the sunroof sealer application process and detects possible product defects based on the SVM(Support Vector Machine) algorithm. The proposed system construction method was actually tested and applied to auto parts makers equipped with the sunroof sealer application process, and as a result, the superiority, reliability, and field applicability of the proposed method were proven.

Of the daily noises, construction noises cause serious conflicts between a construction firm and residents due to their high sound pressure level and shocking, repetitive sound. While South Korea regulates construction noises on the basis of legal criteria to minimize the damage from the noises, the regulation only involves a weighted sound level (dB(A)), which is loudness, like other types of noises. However, since construction noises are characterized by very diverse spectra and waveforms, it has been indicated that they cannot be reflected only by physical loudness: SPLdB(A). In addition, the need to reflect acoustic psychological characteristics and meanings of human beings in evaluating construction noises has recently been indicated. This study aimed to use six Zwicker parameters to determine the sound quality and acoustic psychological characteristics of construction noises and analyze the correlation between physical indexes of construction noises, as found in literature review, and the Zwicker parameters. Loudness of construction noises were closely correlated with SPLdB(A); shocking noises were perceived as ‘loud, sharp, and annoying’ sound. The Zwicker parameters were most strongly correlated with loudness, followed by unbiased annoyance and sharpness, among the evaluation indexes; as for correlation with construction noises, ‘normal noises’ were closely correlated with loudness, ‘shocking noises’ were closely correlated with loudness, unbiased annoyance, and sharpness, and ‘fluctuating noises’ were closely correlated with loudness. Therefore, if loudness, unbiased annoyance, and sharpness were taken into account in terms of the sound quality in evaluating construction noises, it is expected to be useful to make and revise criteria for regulating the noises.

This study analyzed the water quality characteristics and developed empirical models prior to and after the construction of Baekje Weir, in the Geum River watershed between 2004-2017. The comparative evaluation of the surface water chemistry before and after the four major river projects on the weirs indicated that total phosphorus (TP), based on annual data, rapidly decrease after the construction of the weir while the total nitrogen (TN) decreased. Conversely, chlorophyll-a (CHL) concentration, which is a good indicator of primary productivity, increased after the construction of the weir together with an increase in specific conductivity. Simply put, the construction of the weir led to the decrease in concentrations of N and P due to the increased water residence time (WRT), whereas the CHL : TP ratio greatly increased in magnitude. The regression analysis of the empirical model indicated that CHL had no significant relation (r=0.068, p=0.6102, n=58) with TP before the weir construction, but had a relation with TP after the weir construction (r=0.286, p<0.05, n=56). Therefore, such conditions resulted in an increase in primary productivity on a given unit of phosphorus, resulting in frequent algal blooms. In contrast, seasonal suspended solids (SS) and TP increased during the monsoon period, compared to the pre-monsoon, thereby showing positive correlations (r>0.40, p<0.01, n=163) with precipitation. If the government consistently discharges water from the weir, the phosphorus concentration will be increased due to its reversion to a lotic waterbody from a lentic waterbody hereby reducing algal blooms in the future.

본 연구는 금강수계의 백제보 부근에서 이･화학적 수질의 시간적 변이 파악을 위해 2004 ~ 2017년까지 측정된 환경부 수질자료를 분석하였다. 이용된 수질 변수는 전기전도도(Electric conductivity, EC), 용존산소량(Dissolved oxygen, DO), 수온, 생물학적 산소요구량(Biological oxygen demand, BOD), 화학적 산소요구량(chemical oxygen demand, COD), 총인(Total phosphorus, TP), 총질소(Total nitrogen, TN) 및 총부유물(Suspended solid, SS)의 항목으로 이들의 수질특성은 연별, 계절별로 큰 변이를 보였다. 총인 및 이온희석현상의 지표로 이용된 전기전도도는 계절별 분석에서 장마기에 크게 감소하는 현상을 보이며 강우와 역상관관계(p<0.01, n=163)를 보였으나, 계절별 총인은 갈수기에 비해 장마기에 증가하는 특성을 보여 강우와 상관관계(p<0.01, n=163)를 보였다. 한편, 생물학적 산소요구량 및 화학적 산소요구량은 강우와 유의한 관계(p>0.05, n=163)를 보이지 않았고, 계절별 총부유물 농도는 강우기에 크게 증가했고 강우와 유의한 관계(p<0.01, r=0.6155)를 보였다. 생물학적 산소요구량의 계절적 변화패턴은 화학적 산소요구량과 유사한 양상(r=0.4751, p<0.01)을 보였으며, 마찬가지로 총질소의 변화 패턴 또한 총인과 유사한 양상(r=0.0579, p<0.01)을 보였다. 보 건설로 인한 수체의 정체와 유량 증가로 인해 총인과 총질소가 심층으로 침전되어 백제보 건설 전에 비해 건설 후에 감소하는 특성을 보였고, 용존산소량은 보 건설 후에 증가하는 현상을 보였다. 4대강 사업 후 물리적 환경변화에 기인한 수질 변화 분석 결과에서 녹조량 감소를 위해서는 지속적인 총인 관리와 총인 외에도 영양염류 조절, 생물학적 산소요구량 증가를 유발하는 비점오염원관리 등이 시급하다는 것을 알 수 있다.

This study is for figuring out major components of construction quality infrastructure and suggesting improvement plan by benchmarking global best practice model and analyzing gap between the model and sample practice. Based on improvement plan, researcher could derive major characters and components of construction quality infrastructure, and also about the priority among core competency components of construction quality experts. The result showed that the 'human resource' was ranked the best priority followed by 'method' 'environment', 'equipment' among major characters and components of construction quality infrastructure. Also, for core competency components of construction quality experts, 'number of years in work places' was the best priority, and the 'professional knowledge on engineering' was another priority ranked. Far from general perception on competency components, 'academic education' ranked the last. It may allude that the current education system in this country is not effective in developing competency of quality engineers. In summary, this study shows professionalism of quality engineer is the most important thing in all the components.

Torque control method and turn of nut method are specified as clamping method of high strength bolts in the steel construction specifications. Quality control of torque coefficient is essential activity because torque control method, which is presently adopted as clamping method in domestic construction sites, is affected by variation of torque coefficient. This study was focused to evaluate the effect of environmental factors and errors of installing bolts during tightening high strength bolts. The environmental parameters were composed of 'wet' condition, 'rust' condition, 'only exposure to air' condition.

Quality management system(QMS) made by international standard organization(ISO) for the testing and analysis bodies is increasingly required when countries trade their goods according to global trade regulations. This paper mentioned how to build the quality management system on domestic environmental measurement institutions and international trends on global environmental market. A conformity assessment system corresponded with the global standard and regulations has sharply been on the rise in all industrial fields as well as the environmental markets. Accordingly we should construct an appropriate QMS operation to promote analysis precision and spreading to all industrial sectors in order to survive on rapidly changing the current tendency of the times. Through this way, we can have global competitiveness. Especially, the settlement of a systematic and scientific quality assurance system is the key subject from the environmental analytical bodies to every societal industrial institutions.

The methods for constructing network of observational locations for measuring water quality in water reservoirs have been widely proposed, but they had some limitations to be applied to river areas, which lie in awkward clustering and finding representati

소입경 골재노출콘크리트포장은 콘크리트 포장 시공 시 포장표면에 적정 응결지연제를 분사한 후 표면 모르타르를 제거하여 굵은 골재를 노출시킴으로서 표면조직을 형성하는 공법으로써 기존 콘크리트 포장의 소음문제를 해결할 수 있는 저소음 공법이다. 소입경 골재노출 콘크리트 포장은 강도를 크게 개선할 뿐만 아니라 소음저감 효과 및 우수한 미끄럼 저항성을 확보하여 도로이용자의 안정성을 확보할 수 있는 공법이다. 현재 국외 도로 선진국의 경우 골재노출 포장의 상용화가 이루어진 상태이지만 국내의 경우는 실용화 초기단계이기 때문에 현장적용을 위해서는 국내 여건에 맞는 합리적인 관리 기준이 필요하다. 이를 위하여 소입경 골재노출 콘크리트 포장의 최적배합 및 노출기법 연구, 굵은 골재의 선정 및 입도 설계, 환경하중 저항성 평가 등 실내시험을 수행하였으며, 소입경 골재노출 콘크리트 포장의 시공을 위한 시공 장비를 제작하였다. 따라서 본 연구에서는 시험시공을 통해 도출된 결과와 기존 실내시험에서 도출된 결과를 비교 분석하였으며, 시험시공 분석을 통하여 골재 탈리 방지, 강도 및 내구성 확보를 위한 표준배합을 제시하였다. 환경 및 시공조건이 상이한 3차례 시험시공 구간을 선정하여 시공현장여건에 유동성으로 대처할 수 있는 시공 기술 및 시공 기준을 제시하였다. 또한 장 단기 공용성 평가를 통하여 도로 포장의 기능성 측면에서 우수한 소음저감 및 미끄럼 저항성을 확보할 수 있는 노면조직의 품질관리 기준을 제시하였다.

  Goal of "Single PPM Quality Innovation Movement" is to achieve perfect quality through participation of all members in the production line to achieve zero defects.   Six Sigma has been used by many leading corporations as a tool for Management Innovatio