• 한국도로학회논문집
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• 제17권3호
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• pp.97-105
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• 2015

PURPOSES : The Toll Collection System (TCS) operated by the Korea Expressway Corporation provides accurate traffic counts between tollgates within the expressway network under the closed-type toll collection system. However, although origin-destination (OD) matrices for a travel demand model can be constructed using these traffic counts, these matrices cannot be directly applied because it is technically difficult to determine appropriate passenger car equivalent (PCE) values for the vehicle types used in TCS. Therefore, this study was initiated to systematically determine the appropriate PCE values of TCS vehicle types for the travel demand model. METHODS : To search for the appropriate PCE values of TCS vehicle types, a traffic demand model based on TCS-based OD matrices and the expressway network was developed. Using the traffic demand model and a genetic algorithm, the appropriate PCE values were optimized through an approach that minimizes errors between actual link counts and estimated link volumes. RESULTS : As a result of the optimization, the optimal PCE values of TCS vehicle types 1 and 5 were determined to be 1 and 3.7, respectively. Those of TCS vehicle types 2 through 4 are found in the manual for the preliminary feasibility study. CONCLUSIONS : Based on the given vehicle delay functions and network properties (i.e., speeds and capacities), the travel demand model with the optimized PCE values produced a MAPE value of 37.7%, RMSE value of 17124.14, and correlation coefficient of 0.9506. Conclusively, the optimized PCE values were revealed to produce estimates of expressway link volumes sufficiently close to actual link counts.

• 한국구조물진단유지관리공학회 논문집
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• 제11권6호
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• pp.113-120
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• 2007

연약지반에 시공되는 보강토옹벽과 개비온옹벽에 대해서 옹벽의 안정성을 확보하기 위해 필요한 적정 치환영역을 유한요소해석을 통해 검토하였다. 해석은 연약토층의 압밀단계를 포함하여 시공순서를 모사하는 단계별 해석방법으로 수행되었다. 적정 치환영역의 제안을 위한 첫 단계로 치환깊이를 변화시킨 경우들에 대해서 시공단계에 따른 벽체 및 주변 지반의 거동을 조사하는 일련의 해석을 수행하였다. 이들 해석결과를 문헌연구를 통하여 설정한 옹벽의 안정성을 보장할 수 있는 벽체변위, 지반의 침하량 및 전단변형율 등의 한계값과 비교, 평가하였다. 그 결과, 본 연구에서 검토한 지반조건에서 벽체의 높이가 변하는 경우에 대한 적정 치환영역을 벽체의 높이에 대한 치환깊이의 비로 나타내는 시공표준도를 제안하였다

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2001년도 학술대회지
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• pp.301-304
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• 2001

재시공 발생에 따른 계약단계에서의 적정계약공기와 적정투입인원을 추정하고자 한 본 연구는 아파트 RC공사 현장사례를 대상으로 계약금액, 계약기간, 재시공발생현황을 조사하였으며, 이를 토대로 재시공발생에 따른 적정계약공기 및 적정출력인원을 추정하였다. 이와 같은 절차 및 방법에 따라 수행된 본 연구의 결과를 요약하면 다음과 같다. 각 사례규모별 적정계약공기 및 적정출력인원 첫째, 아파트 4동 규모(계약금액 40억$\pm5\%$)인 경우에서의 적정계약공기는 750일 이상 $\~$800일 미만으로 조사되었으며, 적정계약공기를 기준으로 한 1일 적정 출력인원은 63.5명으로 나타났다. 둘째, 아파트 8동 규모(계약금액 78억$\pm5\%$)인 경우에서의 적정계약공기는 850일 이상 $\~$900일 미만으로 조사되었으며, 적정계약공기를 기준으로 한 1일 적정 출력인원은 100.6명으로 나타났다. 셋째, 아파트 12동 규모(계약금액 115억$\pm5\%$)인 경우에서의 적정계약공기는 1000일 이상 $\~$1050일 미만으로 조사되었으며, 적정계약공기를 기준으로 한 1일 적정 출력인원은 145.0명으로 나타났다.

• Nuclear Engineering and Technology
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• 제51권8호
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• pp.1905-1915
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• 2019

This paper investigated the influence of simple support girds on flow, irrespective of having mixing vanes, in a 1 × 3 array rod bundle by using CFD methodology and the most accurate turbulence model which could reflect the actual physics of the flow was determined. In this context, a CFD model was created simulating the experimental studies on a single-phase flow [1] and the results were compared with the experimental data. In the first part of the study, influence of mesh was examined. Tetra, hybrid and poly type meshes were analyzed and convergence study was carried out on each in order to determine the most appropriate type and density. k - ε Standard and RSM LPS turbulence models were used in this section. In the second part of the study, the most appropriate turbulence model that could reflect the physics of the actual flow was investigated. RANS based turbulence models were examined using the mesh that was determined in the first part. Velocity and turbulence intensity results obtained on the upstream and downstream of the spacer grid at -3d_h, +3d_h and +40d_h locations were compared with the experimental data. In the last section of the study, the behavior of flow through the spacer grid was examined and its prominent aspects were highlighted on the most appropriate turbulence model determined in the second part. Results of the study revealed the importance of mesh type. Hybrid mesh having the largest number of structured elements performed remarkably better than the other two on results. While comparisons of numerical and experimental results showed an overall agreement within all turbulence models, RSM LPS presented better results than the others. Lastly, physical appearance of the flow through spacer grids revealed that springs has more influence on flow than dimples and induces transient flow behaviors. As a result, flow through a simple support grid was examined and the most appropriate turbulence model reflecting the actual physics of the flow was determined.

• 한국직업건강간호학회지
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• 제17권1호
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• pp.86-95
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• 2008

Purpose: The objectives for this study are to produce the comprehensive management indexes and find their application strategies for appropriate medical care in primary care clinics under workers' compensation insurance. Method: Data of this study was workers' compensation insurance medical fees claim's data from July 2006 to June 2007. Data were analyzed using SAS 9.1 version by applying descriptive statistics and Pearson's correlation. The indexes such as costliness index(CI), standard medical fee were calculated based on the fourth revision of korean classification of diseases(KCD-4.). Results: The CI, visiting index(VI), outliers index(OI), and medical review adjustment percentage were positively correlated in the both inpatient and outpatient medical fees in primary care clinics under workers' compensation insurance. The major medical specialities were neurological surgery, general medicine, general surgery, rehabitational medicine, and orthopedic surgery. The CIs were slightly high in rehabitational medicine among major medical specialities. The CIs were mostly high in diagnosis, test, anesthesia, and rehabitational assistive device fees among major medical specialities. The CIs were slightly high in Kwangju, Daegu, Daejeon, and Busan districts among district management centers of Korea Workers' Compensation and Welfare Service. Conclusions: We suggest the continuous development of appropriate disease classification system and medical care quality indicators to successfully take root the comprehensive management for appropriate medical care under workers' compensation.

• 해양환경안전학회지
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• 제21권3호
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• pp.274-282
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• 2015

This research is the result on calculating the logical speed limit through certain process which some elements must be considered on selecting the speed limit of harbour and waterway. The suggested speed limit select model on this research is processed from 1~6 steps by forming a professional group of experts. Each step has its information which 1st step(water division), 2nd step(selecting the model vessel and vessel applied with speed limit.), 3rd step(selecting the maximum and minimum speed range on each section), 4th step(evaluation on the safeness of traffic), 5th step(suggesting the appropriate speed limit), 6th step(execution and evaluation.). The appropriate speed limit was decided on consideration of the safety of maritime traffic on the range of the maximum speed and the minimum speed. This model was used to derive the appropriate speed limit on the harbour water and Busan harbour entrance waterway. As the result, the harbour water was calculated to be 6.9 knots, the appropriate speed limit of Busan entrance harbour was 9.3 knots. The present calculation of the speed limit on the approaching channel area is 10 knots, inner harbour area is 7 knots, which are similar to the result of the speed limit. This research is the first research on selecting the speed limit model and has its limits on finding the perfect speed limit result. More detailed standards on the safeness of traffic evaluation must be found and additional study is necessary on discriminating consideration of the elements. This research has its value which it provides instances of aboard cases on guidelines of selecting the speed limit.

• Restorative Dentistry and Endodontics
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• 제45권2호
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• pp.21.1-21.12
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• 2020

The aim of this article was to review age-dependent clinical recommendations for appropriate root canal instrumentation techniques. A comprehensive narrative review of canal morphology, the structural characteristics of dentin, and endodontic outcomes at different ages was undertaken instead of a systematic review. An electronic literature search was carried out, including the Medline (Ovid), PubMed, and Web of Science databases. The searches used controlled vocabulary and free-text terms, as follows: 'age-related root canal treatment,' 'age-related instrumentation,' 'age-related chemo-mechanical preparation,' 'age-related endodontic clinical recommendations,' 'root canal instrumentation at different ages,' 'geriatric root canal treatment,' and 'pediatric root canal treatment.' Due to the lack of literature with practical age-based clinical recommendations for an appropriate root canal instrumentation technique, a narrative review was conducted to suggest a clinical algorithm for choosing the most appropriate instrumentation technique during root canal treatment. Based on the evidence found through the narrative review, an age-related clinical algorithm for choosing appropriate instrumentation during root canal treatment was proposed. Age affects the morphology of the root canal system and the structural characteristics of dentin. The clinician's awareness of root canal morphology and dentin characteristics can influence the choice of instruments for root canal treatment.

• Safety and Health at Work
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• 제9권1호
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• pp.10-16
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• 2018

Background: A detailed evaluation of the underground mine climate requires extensive measurements to be performed coupled to climatic modeling work. This can be labor-intensive and time-consuming, and consequently impractical for daily work comfort assessments. Therefore, a simple indicator like a heat stress index is needed to enable a quick, valid, and acceptable evaluation of underground climatic conditions on a regular basis. This can be explained by the unending quest to develop a "universal index," which has led to the proliferation of many proposed heat stress indices. Methods: The aim of this research study is to discuss the challenges in identifying and selecting an appropriate heat stress index for thermal planning and management purposes in underground mines. A method is proposed coupled to a defined strategy for selecting and recommending heat stress indices to be used in underground metal mines in the United States and worldwide based on a thermal comfort model. Results: The performance of current heat stress indices used in underground mines varies based on the climatic conditions and the level of activities. Therefore, carefully selecting or establishing an appropriate heat stress index is of paramount importance to ensure the safety, health, and increasing productivity of the underground workers. Conclusion: This method presents an important tool to assess and select the most appropriate index for certain climatic conditions to protect the underground workers from heat-related illnesses. Although complex, the method presents results that are easy to interpret and understand than any of the currently available evaluation methods.

• 대한지역사회영양학회지
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• 제24권2호
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• pp.97-105
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• 2019

Objectives: This study examined whether the infant feeding type and duration are related to the introduction of complementary feeding, and whether the appropriate introduction of complementary feeding in infancy is related to tooth decay in toddlers. Methods: The subjects were 1,521 toddlers among 2~3 year old children in the Korea National Health and Nutrition Examination Survey from 2008 to 2015. The toddlers were divided into the appropriate group (4~6 months) and delayed group (>6 months) according to the timing of complementary feeding introduction. Results: The delayed group were 26.5% of subjects and the formula feeding period in the appropriate group and delayed group was 8.4 and 10.3 months, respectively (P=0.002). On the other hand, there was no difference in the breastfeeding period between the appropriate group and delayed group (P=0.6955). Early childhood caries was more common in the delayed group (P=0.0065). The delayed introduction of complementary feeding was associated with a risk of early childhood caries according to the logistic models (OR 1.81, 95% CI 1.27-2.57). Conclusions: The introduction of complementary feeding is associated with early childhood caries. Therefore, the importance of the proper introduction of complementary feeding in infancy should be emphasized, and public relations and education for maternal care and breastfeeding should be provided through health care institutions.

• 산업경영시스템학회지
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• 제42권3호
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• pp.61-69
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• 2019

The concept of carsharing involves sharing a small number of reserved cars to be used individually by a larger number of people as required. This study examines the operating parameters of one-way carsharing systems in order to determine the appropriate operating conditions that minimizes the lost sales rate. Five operating parameters are tested in this study: the number of stations, the average number of vehicles per station, the rate of one-way trip, the average number of staffs per station, and the relocation policy. The performance of round-trip carsharing systems is also compared to that of one-way carsharing systems. A simulation model is developed and simulations are performed to determine the appropriate combination of operating parameter and levels. The simulation results show that the average number of vehicles per station is the most critical parameter. Other key findings obtained from this research are as follows. First, applying the appropriate relocation policy to one-way carsharing systems can allow more customers to rent vehicles than the traditional round-trip carsharing systems. Second, the appropriate relocation policy should be selected based on the average number of vehicles per station in order to minimize the lost sales rate. Third, the number of stations does not affect the lost sales rate. This study findings will provide tools to understand impact of the carsharing system parameters on the efficiency of the carsharing operations.