• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.5-6
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• 2016

When concrete exposed to low temperatures, the free water in the concrete is freeze. If the pressure developed exceeds the tensile strength of the concrete, the cavity will dilate and rupture. It cause expansion and cracking, scaling and crumbling of the concrete. In this study, to prevent such damage, five different types of form were used. Concrete was poured into each form, cured for 7 days at temperature of -10℃. To measure the temperature history, two thermocouples were installed on each of the inside and outside. And to measure the compressive strength, collected core from each form. The maturity is formed by temperature history. The maturity and the compressive strength has a correlation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.251-252
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• 2012

The exiting studies on the strength prediction by maturity method is mainly focused on concrete using OPC, meanwhile the study on the concrete mixing blast furnace slag powder (BFSP) is insufficient. The purpose of this study is to investigate the relationships between compressive strength and equivalent age by existing Maturity functions, i.e., Nurse-saul function Arrhenius function. This study also compared and examined the strength prediction of concrete mixing BGSP using ACI model and Logistic Curve prediction equation. Therefore, it is intended that fundamental data are presented for quality management and process management of concrete mixing BFSP.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.3
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• pp.35-41
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• 1998

Cost estimate system Will be changed from the prime. cost calculation to the historical cost data because the present system has some problems. In this situation, each owner should prepare his own cost estimate system based on the historical cost data. In this study, the standard work items were classified and the criteria of their work amount computation were established for rural improvement projects. And also the historical cost data were collected in all range of rural improvement projects, and the database system, "HICOMS" (HIstorical COst data Management System) was built. In order to test the applicability of the HICOMS, standard work cost and contractor cost were compared. The results by HICOMS showed high significance and it was concluded that the HICOMS could be applicable for the cost estimate of the rural improvement projects. projects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.4
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• pp.332-339
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• 1988

Using a generalized observation model, in which one can express the effects of non-additive noise such as signal-dependent noise and multiplicative noise in addition to purely-additive noise, the problem of weak random-signal detection is investigated. It is shown that the test statistics of locally optimum detectors for detection of weak random signals in signal-dependent noise model are interesting extensions of those in purely-additive noise model. This result is a complement to the result for weak random-signal detction in multiplicative noise model.

• Environmental engineer
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• v.23 s.244
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• pp.56-60
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• 2006

최근 수질환경보전법의 개정법률(안)에 의거하여 폐 · 하수종말처리장에 수온, pH, 생물학적산소요구량(BOD), 화학적산소요구량(COD), 총질소(TN), 총인(TP) 및 부유물질(SS)의 자동으로 측정할 수 있는 수질 자동측정기의 부착이 의무화될 예정에 있다. 그러나, 현재 전국적으로 화학적산소요구량 측정장비와 같이 일부 항목에 대한 자동측정장치는 설치 · 운영 중인 곳이 많이 있으나, 수질 TMS 설치 규정에 나와 있는 전 항목을 측정할 수 있는 장비가 설치되어 운영하는 곳은 극히 일부에 불과한 실정이다. 따라서, 수온, ph, 화학적 산소요구량(COD), 총질소(TN), 총인(TP), 부유물질(SS) 자동측정 장치를 설치하고, 무선통신(CDMA)방식을 이용하여 ‘방류수 수질 원격감시체계(TMS) 시범 운영'을 통하여, 측정 장비들에 대한 자료의 정확성, 신뢰성을 파악하여 설치된 장비들에 대한 성능을 사전에 평가하고, 수질 TMS 시스템에 대한 현장 적응 능력 및 안정성을 파악하여 실질적으로 운영되는 시점에 좀 더 정확하고 실용적인 시스템의 적용하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.505-509
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• 2002

남해 중부해역에서 적조발생과 관련해서 적조 다발월인 여름과 초가을에 기온과 마찬가지로 높은 수온을 유지한다. 또한 많은 강수량에 의하여 부유물질 및 영양염류가 증가하고 염분이 대체로 떨어지는 것을 알 수 있었다. 이때 적조의 bloom으로 인하여 대표적인 영양염류인 질소와 인의 값이 떨어진다. 그리고 적조생물의 사후 미생물 분해 작용이 활발하여 산소의 소모가 증가하여 용존산소가 급격히 떨어지고 화학적산소요구량이 높게 나타나는 것을 알 수 있었다. 즉, 해양인자와의 상관성은 적조의 발생조건인 수온이 적당하며 저염분과 부유물질, 클로로필, 질소, 인이 높게 나타났고 용존산소는 적조생물의 인해 낮게 나타났음을 알수 있었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.67-68
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• 2019

The mechanical and durability characteristics of concrete structures depend on the construction environment, material conditions, design conditions, and temperature and humidity environment after casting. However, wired communicati-on sensors which are mainly used in the field have many limitations in their usability and monitoring. In this study, all temperature and humidity data measured from embedded sensors are monitored via a wireless sensor network. Based on the measured temperature data, the predicted compressive strength of the concrete was compared with the actual compressive strength. As a result, The error between predicted strength and experimental strength has decreased over time.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.94-95
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• 2018

Prediction of compressive strength of concrete by Maturity Method is applied in construction site. However, due to the use of wired type high-priced equipment, economic efficiency and workability are falling. In this study, a newly developed concrete embedded wireless sensor is used to perform a mock-up test. Next, the concrete compressive strength of the Maturity Method is predicted using Saul and Plowman's function as measured temperature data. The predicted concrete strength at the beginning of the age was the actual strength and stiffness, but the error rate was less than 1% at 28th day.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.222-223
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• 2014

According to the improvement of IT technology, an enhanced efficiency of management system in the construction industry is expected since a quotation system with BIM (Building Information Modeling) technique effectively estimates construction materials. For an enhanced efficiency of management system, related guidelines, standards, and manuals based on BIM are required, but the lack of this information causes difficulty to utilize in practice. In the paper, the satisfaction analysis was performed in order to promote the completeness of construction estimating manager that can be presented criteria and details of BIM-based quantity-takeoff, classification criteria.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.2
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• pp.99-107
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• 2000

The objective of this study are to compare the development of compressive strength of epoxy mortars used as repairing materials with respect to maturity , and to propose a model predicting strength development of epoxy mortars. A series of tests are carried out for the hardener contents of 30, 40 and 50 percentage of epoxy resin and compressive strengths are measured at the age of 6, 12, 24, 72, 120 and 168 hours respectively under the cure temperature of 0, 10, 20 and 3$0^{\circ}C$. The datum temperature is estimated by measured strengths, and the maturity is calculated with the estimated datum temperature. The compressive strength of epoxy mortars can be predicted by regression analysis from the maturity-compressive strength relationship.