시멘트 콘크리트 포장의 양생 공정에서는 피막양생제를 살포하는 것이 가장 일반적이며 양생포와 같은 덮개를 콘크리트 포장 위에 덮어 온도와 습도를 유지하는 방법으로 콘크리트 포장의 강도를 발현시키기도 한다. 콘크리트 포장의 미끄럼 저항 및 배수, 주행안전 성을 향상시키기 위해서는 양생 공정 이전에 표면 타이닝 공정을 수행하는 것이 일반적이지만 양생 이후에 그루빙을 실시하기도 한다. 본 연구에서는 콘크리트 포장 품질에 지대한 영향을 주는 양생 작업과 표면 그루빙 작업의 일원화 방법 개발을 위한 기초 연구로써 3D 스케치 프로그램과 3D 프린터를 이용하여 타원형, 삼각형, 사각형 모양의 홈으로 그루빙을 형성하면서 동시에 양생포로 사용이 가 능한 그루빙 양생 플레이트를 설계하여 제작하였다. 그루빙 양생 플레이트의 적용성을 분석하기 위해 콘크리트 공시체를 제작하여 실 내 실험을 수행하였으며 양생 플레이트의 그루빙 홈 형상에 따른 콘크리트 포장 표면 그루빙 형성 상태를 분석하였다.

The overseas small ship market is witnessing a trend towards research aimed at substituting Fiber Reinforced Plastics (FRP), which poses environmental concerns, with High-Density Polyethylene (HDPE) in the shipbuilding process. Given the low melting point and high coefficient of thermal expansion of HDPE, research on joint areas is essential. This study focuses on preliminary investigations into ensuring the integrity of joints in shipbuilding processes using HDPE materials. Utilizing the Hot Gas Extrusion Welding method, which is conducive to joining large structures such as ships, HDPE joints were conducted. The material properties were evaluated based on the ASTM D638-14 international standards. This research aims to provide fundamental knowledge on the joining process of HDPE through Hot Gas Extrusion Welding and offers guidance on ensuring the integrity of joints in shipbuilding.

Asphalt concrete, which is used as a road base material, accounts for >90% of a road pavement. A huge amount of waste concrete and waste asphalt concrete aggregates are generated. Recently, carbon neutrality is promoted across all industries for sustainability. Therefore, to achieve carbon neutrality in the asphalt concrete industry, waste asphalt concrete aggregates should be recycled. Additionally, road base materials are prepared using additives to ensure structural stability, durability, and economic efficiency. In this study, recycled asphalt concrete aggregates were used to evaluate the physical properties of road base materials according to the type of polymer additive and mixing method, and the applicability of road base each material was evaluated. Results showed that when the acrylate-based polymer additive was mixed, the uniaxial compressive strength was 30% higher. Furthermore, the compressive strength of the split mix was improved by ~29% compared to the total mix.

선박 및 교량 구조물은 일종의 길이가 긴 박스형 구조로서 수직 굽힘 모멘트에 대한 저항력이 설계의 주요 인자이다. 특히 선박 거더는 반복적으로 불규칙적인 파랑하중에 장시간 노출되어 있기 때문에 구조부재의 연속 붕괴 거동을 정확하게 예측하는 것이 무엇보다 도 중요하다. 본 논문에서는 순수 휨모멘트를 받는 박스거더의 하중 변화에 따른 좌굴을 포함한 소성 붕괴 거동을 수치해석적 방법을 이용 하여 분석하였다. 분석대상은 Gordo 실험에서 사용한 세 가지 박스거더로 선정하였다. 구조강도 실험 결과와 비선형 유한요소해석에 의한 결과를 비교하여 차이가 발생하는 원인에 대해서 고찰하였다. 본 논문에서는 카본스틸 재료의 제작 시 필연적으로 사용하는 용접열에 의한 초기 처짐의 영향을 반영하기 위하여 전체와 국부적인 처짐 형상의 조합을 제안하였고, 이 결과는 실험 결과와 거동 및 최종강도 추정율이 7% 이내에서 잘 일치하고 있었다. 논문에서 검토한 절차 및 초기 처짐 구성에 대한 내용은 향후 유사 구조물의 최종강도를 분석하는데 좋 은 지침으로 사용할 수 있다.

In the wire constituting the LIN, which is one of the vehicle communication devices, disconnection of the wire or contact resistance of the circuit occurs due to vibration and aging of the vehicle. This affects the entire communication network and may have a significant impact on the safe driving of the vehicle as information is not transmitted. In this study, a LIN BUS circuit simulator was built on its own like a real car and measured with an automotive oscilloscope instead of a common method of measuring and diagnosing a circuit with a multimeter in the event of a LIN BUS circuit failure. Referring to the experimental results, it will be possible to diagnose faults in circuits efficiently and quickly.

Most of the steam turbine control valves used for the fossil and nuclear power plants operation in South Korea were developed by GE (General Electric) and manufactured by DHIC (Doosan Heavy Industry Company). For may years, DHIC have tried to develop their own technologies related to the power generation. DHIC has launched many R&D projects and ‘Development of a Control Valve Flow Code for Steam Turbine Operation Control of Fossil Power Plant’ was one of the R&D projects. Through our project, we accomplished the experimental method to obtain a steam turbine control valve characteristic curve using the atmospheric air and the reduced model instead using the steam and the real model. Also, we developed the correction method to calculate the real steam mass flow rate from the characteristic curve obtain by the experiment. In this paper, the effectiveness of the correction method was reviewed and it was concluded that the corrected mass flow rate complies well with the real steam mass flow rate.

Screws are the closest and most familiar mechanical elements of everyday life, and are generally used so widely that there is no machine without screws. Screws are used to make it easier to combine objects with objects, and are also used to transfer large forces from machines. The most influential factor in the coupling of these screws is the effective diameter. If the effective diameter is not accurate, the support cannot be finished or endured, leading to a major accident. The importance of these screws cannot be ignored, so in this study, the effective diameter was measured using the three-wire method, the screw micrometer method, and the projector method, and the one-way factor design method was applied to determine the exact method compared to the KS standard.

PURPOSES : The objective of this study is to present a practical application method for measuring the setting time of concrete in the field, considering different concrete blending and curing environments. METHODS : In the experimental environment of the concrete setting experiment, a mold was made in the laboratory, and the curing temperature was performed at laboratory room temperature (20-25 ℃), heater (30 ℃), and dryer (40 ℃). In the field, the experimental method was performed in summer and autumn, setting experiments on penetration resistance, ultrasonic pulse velocity, and semi-calorimeter. RESULTS : The result of the concrete setting time experiment was that the early setting time was achieved in the combination of filash and slag when the concrete was mixed, and the setting time in the curing environment was the same as the early setting time in the field. The setting time measurement method shows the correlation of the high crystal coefficient at UPV with 0.99 based on PR and the good ratio of 92 % to 107 % on average. In addition, the semi-calorimeter shows a good crystal coefficient of 0.96 to 0.99 and a good setting time of 88 % to 101 % on average. CONCLUSIONS : The analysis of the setting time of the concrete shows that the curing temperature is more affected than the mixture, and it is considered that the UPV test, which evaluates the reliability of the degree of purification, is easy to sampie among the three methods.

최근 대규모 토목 및 건축 구조물 증가 추세로 건설 부재의 고강도 및 경량화에 대한 수요가 높아지고 있다. 기존 시멘트 경량 복합체의 경우 단위 체적 중량이 낮아 강도 저하 문제가 발생할 수 있다. 보통 경량화를 위해서 시멘트 복합체를 배합할 때 일반 경량골재와 고무재질의 경량골재, 플라스틱 펠릿 등 다양한 인공 경량골재를 적용한 시멘트 복합체로 경량화를 확보할 수 있다. 이 중에서도 시멘트 복합체의 인공 경량골재로 플라스틱을 사용하면 상대적으로 골재 자체의 강도를 확보하면서 경량화를 꾀할 수 있지만 재료의 매끄러운 표면 특성으로 인해 시멘트 페이스트와 부착하는 데 불리한 부분이 있고 이는 콘크리트 골재 또는 시멘트 복합체 골재로서의 사용에 있어 단점이 된다. 띠라서 이번 연구에서는 기존 연구에서 플라스틱 골재 로 가장 적합한 유형으로 확인된 PP, PE 두가지 유형의 플라스틱 골재와 강섬유, 양생방법을 변수로 하여 실험을 진행하였고 실험 결과 플라스틱의 비중이나 표면 재질뿐만 아니라 강섬유의 혼입유무, 양생방법에 의해서 시멘트 복합체의 물리적 특성이 변화된다는 것을 확인하였다.

엽상형 해조류의 간접적인 건중량 추정을 위해 구멍갈파래(Ulva australis), 잎파래(Ulva linza), 개도박(Pachymeniopsis lanceolata), 방사무늬김(Pyropia yezoensis)의 형태적 특성과 생체량의 관계를 분석하였다. 시료는 2017년 2월부터 2018년 12월 까지 남해안 6곳에서 채집되었으며, 총 319개체가 분석에 사용되었다. 엽상형 해조류 네 종의 길이와 생체량에 대한 상대성장 지수는 0.28로 일반적인 1/4(0.25) 지수법칙에 해당하였다. 네 종의 엽체의 표면적과 습중량은 각각 건중량과 유의한 선형관계를 보였으며, 건중량의 94~99%를 설명할 수 있었다. 이 결과는 엽상형 해조류의 표면적 또는 습중량을 통해 개체의 건중량을 매우 정확하게 추정할 수 있다는 것을 의미한다. 이 방법론은 실험실 연구에서 건중량을 직접 측정할 수 없을 때 쉽고 빠르게 활용할 수 있으며, 추가적으로 소요되는 시간과 비용을 절약할 수 있을 것이다.

This study aims to gather precise information on the real fabric color and texture, and purchasing intention of mobile shoppers buying clothes. Eighty volunteers participated in the sensory test on three smartphones with four colors and two fabricssmooth taffeta and hairy doeskin. This study carried out the posteriori test using the one-way ANOVA and Duncan test by SPSS21.0. In the analysis’ results of color preference, there were no differences among the four colors of taffeta between the smartphones, but different preferences between the red and yellow doeskin exist. In the case of the Samsung phone, which has an immense color distortion, the red fabric has a low color preference. In contrast, on the Apple phone yellow fabric had the highest preference because of its brightness. The Apple phone also has the highest purchasing intention of yellow colored taffeta, which is similar to the color preference results, although the real fabric has the opposite result. For doeskin, the real red and blue colored fabric has the highest purchasing intention. The Samsung phone has the biggest color mismatch with the real fabric. It also has the lowest purchasing intention of red taffeta fabric, while the LG phone has the lowest purchasing intention of blue fabric. Using the paired comparison method of the similarity between ‘real’ fabrics and the mobile version of fabric colors has a low similarity on all four colors of taffeta and doeskin fabrics. Therefore it can be concluded that phones do not represent the ‘real’ fabric color.

본 연구에서는 플라스틱 온실에서 사용하는 죔쇠의 성능 평가 시 시험편 끝단의 구속조건이 미끄럼 저항력에 미치는 영향을 분석하기 위해 시험편 구속조건을 실험변수로 판형죔쇠의 미끄럼 저항력을 측정하였다. 각 구속조건별로 측정한 미끄럼 저항력의 평균값은 서까래 고정-고정단이 가장 컸으며, 내재해형 죔쇠의 평가 기준 값과 비교한 결과에서도 서까래 고정-고정단의 경우에만 기준을 만족하는 것으로 나타났다. 그러나 서까래 고정-고정단 구속조건은 다른 구속조건들에 비해 산 포도가 상대적으로 크게 나타나 신뢰성이 떨어지는 결과를 보였다. 또한, 일원분산 분석결과에서도 서까래 고정- 고정단은 다른 구속조건들과 비교해 미끄럼 저항력이 유의한 차이를 보였다. 따라서 시험편 구속조건이 미끄럼 저항력 평가에 영향을 미친다고 판단하며 연구자 및 기술자들이 죔쇠의 미끄럼 저항력을 측정할 때에는 시험편의 구속조건이 결과값의 신뢰성에 미치는 영향을 면밀히 검토해야 할 것으로 판단된다.

본 연구에서는 폐콘크리트의 발생지 및 재생골재 생산방법 별로 골재 종류를 나누어 각각 비중, 흡수 율, 마모율, 안정성 실험을 실시하였으며, 결과를 통해 각각의 발생지 및 생산방법에 따른 골재특성의 차 이를 알아보았다. 생산방법에 대한 모식도는 아래의 그림 1과 같다. 실험 결과는 아래의 표 1과 같다.

The two experiments were done on stationary car at 800rpm, 1500rpm and running car on oscilloscope and chassis dynamometer at the speeds of 20km/h, 60km/h. In this experiment, the relativity between waveform, exhaust emissions and fuel consumption through two experimental methods were measured in case of cars with failures in MAP sensor, O sensor, spark plugs. The following results are obtained by analyzing the data relativity between two experimental methods, such as stationary and running tests. A simple stationary test under the maintenance of a decrepit gasoline vehicle would be realistic possibility to predict the fuel consumption and the exhaust emission comparable to results of running test with a chassis dynamometer.

PURPOSES : Capacity is a main factor of determining the number of lane in highway design or the level of service in road on operation. Previous studies showed that breakdown may occur before capacity is reached, and then it was concluded that capacity is a stochastic value rather than a deterministic one. In general, estimating capacity is based on average over maximum traffic volume observed for capacity state. This method includes the empirical distribution method(EDM) and would underestimate capacity. This study estimated existing empirical methods of estimating stochastic highway capacity. Among the studied methods are the product limit method(PLM) and the selected method(SM). METHODS: Speed and volume data were collected at three freeway bottleneck sites in Cheonan-Nonsan and West Sea Freeway. The data were grouped into a free-flow state or capacity state with speeds observed in the bottlenecks and the upstream. The data were applied to the empirical methods. RESULTS : The results show that the PLM and SM estimated capacity higher than EDM. The reason is that while the EDM is based on capacity observations only, the PLM and SM are based on free-flow high volumes and capacity observations. CONCLUSIONS : The PLM and SM using both free-flow and capacity observations would be improved to enhance the reliability of the capacity estimation.

PURPOSES : About 35% of air pollutant is occurred from road transport. NOx is the primary pollutant. Recently, the importance of NOx removal has arisen in the world. TiO2 is very efficient for removing NOx by photocatalytic reaction. The mechanism of removing NOx is the reaction of photocatalysis and solar energy. Therefore, TiO2 in concrete need to be contacted with solar radiation to be activated. In general, TiO2 concrete are produced by substitute TiO2 as a part of concrete binder. However, 90% of TiO2 in the photocatalysis can not contacted with the pollutant in the air and solar radiation. Coating and penetration method are attempted as the alternative of mixing method in order to locate TiO2 to the surface of structure. METHODS : The goal of this study was to attempt to locate TiO2 to the surface of concrete, so we can use the concrete in pavement construction. The distribution of TiO2 along the depth were confirmed by basing on the comparison of TiO2 compare by using the EDAX(Energy Dispersive X-ray Spectroscopy). RESULTS : TiO2 were distributed within 3mm from concrete surface. This distribution of TiO2 is desirable, since the TiO2 induce photocatalysis are located to where they can be contacted with the air pollutant and solar radiation. CONCLUSIONS : Nano size TiO2 is easily penetration in the top 3mm of concrete surface. By the penetration TiO2 concrete can be produced with the use of only 10% of TiO2, by comparing the mixing types.

PURPOSES : This study is to evaluate the feasibility of setting the standard of cement alkali content by using ASTM C 1260(accelerated mortar bar test) METHODS : This study analyzes the ASR(alkali silica reaction) expansion of cement mortar bar based on the changes in the aggregate type(fine, coarse), cement type(ordinary, low alkali), and replacement contents of fly ash. ASR tests were conducted according to ASTM C 1260. RESULTS : In this test results, There is no big difference in the ASR expansion between ordinary cement and low alkali cement. From this test results, it was found that the variation of cement alkali content did not have a effect on ASR expansion because mortar bar was placed in a container with sufficient alkali aqueous solution at high temperature during the test process of ASTM C 1260. CONCLUSIONS : It is evidently clear that the alkali content of cement have a effect on ASR. But ASTM C 1260 is difficult to assess this effect.

태풍 발생과 이동에 미치는 전향력의 영향을 살펴보는데 활용할 수 있는 실험 방법을 개발하였다. 실험 장치는 회전원판, 수조, 그리고 태풍과 유사한 모양의 소용돌이를 생성시키기 위한 발생기 등으로 구성되었다. 회전하는 원판에 놓인 수조에서 생성된 소용돌이는 그 형태가 수 분 동안 유지되었다. 반면에 회전이 없을 때는 소용돌이가 생성되기 어려웠고, 생성되더라도 곧 흩어졌다. 회전 유체의 역학적 특성은 전향력이 작용하는 대기와 유사하므로, 앞의 두 실험을 통해 태풍이 발생되기 위해서는 반드시 전향력이 필요함을 알 수 있었다. 또한 경사진 바닥을 갖는 수조 속의 소용돌이는 일정한 방향으로 이동하였다. 지형적 베타 효과를 고려하여, 우리는 바람 효과뿐만 아니라 전향력의 남북방향의 변화가 태풍의 이동에 중요한 영향을 줄 수 있음을 알았다. 이 연구에서 개발한 실험 방법은 학생들이 전향력과 태풍의 관계를 이해하는데 유용하게 사용될 것으로 기대한다.