Various kinds of friction materials were manufactured by adding 10%, 20%, and 30% of reduced iron, respectively, which has been obtained during the reduction process of blast furnace sludge extracted from the blast furnace, and its iron oxide, instead of existing barium sulfate(BaSO4) among the components of automobile brake friction materials. Fundamental physical property test and friction performance test, etc., using a brake dynamometer were carried out against these friction materials. Furthermore, when the expensive filling material, BaSO4 was substituted by reduced iron and added to the friction material, the added content of reduced iron for an excellent friction characteristic considering the heat emission temperature, wear, etc., was 10%. In the fundamental physical property test, as the added content of blast furnace sludge or reduced iron increased, and as the content increased, the shear strength and bonding strength of friction materials decreased, but both of them indicated sufficient strengths to be applied to a friction material. Even in the frictional performance test using a brake dynamometer, as the added content of blast furnace sludge or reduced iron increased, the friction coefficient reacted insensibly to brake deceleration, and its stability was improved.

PURPOSES : The use of reclaimed aggregate has been recently increasing with the increase in the amount of waste asphalt concrete. The application of these materials can reduce the properties of the asphalt pavement when compared with the case when recycled aggregate is not used. The objective of this study is to evaluate the performance of the asphalt mixtures with various mix ratios of reclaimed aggregate. METHODS : To measure the performance, the following tests using the mixtures prepared in accordance with the Korea Standards were conducted: Hamburg wheel-tracking test, third-scale model mobile loading simulator test, and dynamic modulus test. RESULTS : The test results of the Hamburg wheel-tracking test indicate that the water resistance was similar in each mixture and the plastic deformation resistance was good in the high-ratio reclaimed aggregate mixture. In the case of the third-scale model mobile loading simulator test, the plastic deformation demonstrated a high resistance in the high-ratio reclaimed aggregate mixture. The results were similar to those of the Hamburg wheel-tracking test; however, the cracking resistance was poor with a high recycled aggregate incorporation ratio. The dynamic modulus test results demonstrated excellent resistance to plastic deformation at a relatively high ratio of reclaimed aggregate admixture. The crack resistance was weakened when a high ratio of reclaimed aggregate mixture was used. CONCLUSIONS: As the reclaimed aggregate content increased, the plastic deformation resistance increased and the crack resistance decreased.

The objective of this study was to quantitatively evaluate the influence of the netting hanging ratio on fishing performance of gillnet. A total of six tests was carried out using three kinds of gillnets with different horizontal hanging ratios (0.3, 0.5 and 0.7) on the basis commercial gillnet of mesh size of 60 mm used in Yeosu Dolsan. As a result of the test fishing operation, catches of the net with hanging ratio 0.3 and the shortest float length was 1.34 times larger than the net with hanging ratio 0.7. The caught species in experimental testes was lager in the net with hanging ratio 0.3 than the net with hanging ratio 0.7. The catch rate per unit area (CPUE) is on the silver croaker with the largest catches in tests as follows. The net with hanging ratio 0.3 net was 89.45 g/m2, hanging ratio 0.5 net was 41.63 g/m2, and hanging ratio 0.7 net was 24.50 g/m2. The net with hanging ratio 0.3 (float line length of 45 m) exhibited the largest CPUE value.

In this thesis, it was considered that in durability characteristics of concrete pavements evaluation of strength characteristics as well as abrasion resistance is important as the domestic concrete pavements couldn't fulfill the public needs and cases of damage are increasing. In order to solve such problems, it is intended to compare the abrasion resistance in accordance with the mixing rate of admixtures (silica fume and polymer powder) which are incorporated in the upper layer of two-lift concrete pavement and find the optimum mixing rate for abrasion resistance by focusing on the high performance of concrete pavements through two-lift concrete pavements which use cellular sprayed concrete construction method. Both test results, which were performed based on ASTM C 779 B (dressing wheel abrasion test method) and ASTM C 944 (rotary cutter method) standards in accordance with silica fume and polymer powder mixing rate that was incorporated in the upper layer of two-lift concrete pavement, proofed that the abrasion resistance increased as the mixing rate of silica fume and polymer powder increased. However, it was also confirmed that if the mixing rate of admixtures is excessively increased it will not have an effect and it will rather decrease the abrasion resistance.

In this study, we analyzed the radiant heat performance of ballast fin when the aspect ratio of the fin of ballast was changed. The minimum size of the mesh was 0.02 mm, and the grid number was about more than 11 thousand. In order to analyze the radiant heat performance of ballast fin, the aspect ratio of fin was 1.00(2 mm:2 mm), 1.80(1.5 mm:2.7 mm), and 0.56(2.7 mm:1.5 mm) respectively; that the heat transfer area was constantly 0.4 mm 2 . The numerical condition was that heat flux was constantly 1×10 5 W/m 2 , and measuring times were 0.1 second, 0.2 second, 0.5 second, 2 seconds, 5 seconds and 10 seconds respectively. The temperature values of fin at the 1.00 and 1.80 of aspect ratios were extremely large when heat flux time was 10 seconds. As a result, the maximum value of radiant heat performance of ballast fin appeared to the aspect ratio of 1.80.

To overcome recent emission regulation, various hybrid systems are being developed. In the E-4WD(electric four wheel drive) system, the engine and transmission drive the front wheel, electric motor and single reduction gear drive the rear wheel. As the gear ratio of the reduction gear set determines the electric motor's operating point, the gear ratio is important to enhancement efficiency of hybrid system. This study is to analyze motor reduction gear ratio's influence on E-4WD hybrid system for optimized efficiency and driving performance. Fuel economy, operating point of power source and hybrid mode are analyzed using simulation developed with dynamic programming method.

The objective of this study is to provide improved methodology based on the IPA method. One case studies are solved by the proposed method. this study present the method that give value to use SN(Signal-to-Noise) ratio in IPA. A case study of lecture satisfaction are solved by the proposed method and the existing method. Also, the result is compared with the existing method using Mean and the proposed method using SN ratio.

이 논문은 샌드위치식 강-콘크리트 복합구조체에서 상하 강판과 격벽으로 구성되는 셀의 형상비가 거동과 성능에 미치는 영향을 다루었다. 이 구조체에서 셀 형상비는 하중전달 메카니즘과 하중분배능력을 변화시킨다. 따라서 셀 형상비에 따라 부재의 응력수준과 하중저항능력이 변화한다. 이 연구에서는 셀 형상비가 이 구조체의 거동과 성능에 미치는 영향을 규명하기 위해, 두 종류의 샌드위치식 복합구조체에 대해 다양한 셀 형상비를 설정하여 비선형 구조해석을 수행하였다. 해석결과로부터 셀 형상비에 따른 하중전달 메카니즘과 부채 응력에서의 차이점을 도출하였으며, 이들 차이점을 바탕으로 셀 형상비가 전단성능, 휨성능, 하중저항성능에 미치는 영향을 분석하였고, 파괴모드와 연성에 미치는 영향에 대해서도 간략히 언급하였다. 연구결과, 셀 형상비가 증가함에 따라 하부 강판과 콘크리트의 응력수준이 낮아지는 결과를 나타내었다. 이것은 각 부재의 유효휨강성과 유효전단강성 증가를 나타내며, 따라서 구조체의 하중저항성능도 향상되는 것으로 판단된다. 특히 셀 형상비의 증가에 따른 성능향상에서 전단성능이 휨성능에 비해 더 큰 효과를 나타내며, 이러한 차이는 파괴모드와 연성에도 영향을 미칠 것으로 판단된다. 즉, 셀 형상비가 증가함에 따라 구조물의 거동 및 파괴모드는 점차적으로 전단에서 휨으로 변화하고, 이에 따라 구조물의 연성도 점차적으로 향상될 것으로 판단된다.

본 연구는 해외각국의 RC건물의 내진화기술 가운데, 일본의 기존 RC건물에 대한 내진성능의 평가수법인 내진진단규준의 현황을 소개함과 동시에 그 적용사례 및 지진대책에의 활용가능성을 분석검토하여, 향후 한국실정에 맞는 RC건물의 내진화기술의 개발에 기초적인 자료로서 활용하고자 하는 것이 주목적이다. 이를 위해 본 연구에서는 일본의 동경도에서 최근 실시되어진 지진경험이 없는 RC건물의 내진성능을 내진진단규준에 의한 진단결과인 구조내 진지표(Is)치를 중심으로 통계학적으로 분석하여, 이미 조사되어진 타 지역의 내진성능과 비교검토하였고, 또한 확률론에 입각하여 대상지역의 Is치의 분포특성과 이미 지진 피해를 받은 지역 건물의 Is치 분포특성을 비교검토하여 지진피해율을 추정하였다. 본 연구의 결과는 지진에 대한 보강건물의 효율적인 선정 등, 지진대책에 기본적인 자료로서 활용이 가능하며, 또한 일본의 내진성능 평가방법, 통계학적인 분석방법, 확률론에 입각한 지진피해율 평가방법 등의 방법론은 향후 한국의 RC건물에 대한 내진화기술의 개발에 활용이 가능하다고 사료된다.

활주선 선형을 갖는 고속어선의 저항특성을 체계적으로 연구하기 위한 제 1단계로서 단면형상 및 장-폭비와 저항특성과의 관계에 대한 실험적 연구를 수행하였다. 본 연구는 새로운 고속 활주형 어선을 개발하기 위한 초기연구로서 다음의 내용을 포함하고 있다. - 4가지 단면형상에 대한 저항 특성 - 4가지 장-폭비에 대한 저항 특성

This objective of this study is to enrich the literature by the debt ratio and enterprise performance of Joint stock companies of Vietnam National Coal and Mineral Industries Holding Corporation Limited (Vinacomin). The debt ratio is an important index of capital structure, and it influences and decides the enterprise performance. Therefore, the determination of reasonable debt ratio level is beneficial to the stable operation of Vinacomin’s enterprises. Based on the research conclusion about the effect on capital structure of debt ratio from domestic and foreign scholar, collecting data from 2014-2018 of Vinacomin’s enterprises as a research sample, the article conducts research on the relationship between debt ratio and business performance of Vinacomin, as measured by return on total Assets. In addition, the study uses free cash flow, company size , growth opportunity, investment opportunities, operating costs to sales ratio as control variables.The study shows the debt ratio of Joint stock companies of Vietnam National Coal and Mineral Industries Holding Corporation Limited has a negative effect on the enterprise performance. Furthermore, the research results of the article are references for Vinacomin’ enterprises in the course of production and business activities, determining a reasonable debt ratio, and improving the operational performance of enterprises.

Playing an important role in developing the economy and overall developments of the country, commercial banks have to be aware of their crucial presence in order to perform well and contribute significantly. At the same time, as a place to receive deposits, banks are required to be in safe situations to avoid bankruptcy or deal with financial crises. This research seeks to identify the determinants of Capital Adequacy Ratio and Banks’ performance as well as the relationship between these two dependent variables. The paper uses 128 observations of 16 Vietnamese commercial banks during the period from 2010 to 2017, with two simultaneous dependent variables CAR and ROE, and independent variables including Return on Assets, Tobin Q, Credit growth, GDP growth, Equity to Deposits, Loans to Deposits, Bank size, Cost to Income, Liquidity risk, Provision for Loan loss ratio, Non-performing loans and Inflation. The results reveal that Capital Adequacy Ratio and Banks’ Performance have statistically significant relationship and Credit growth, GDP growth, Equity-to-Deposit ratio and Costto- Income ratio all have significant effects on two dependent variables. The findings of this study suggest that commercial banks should control the respective elements in order to maintain adequate level of capital and also create effective performance.

In this study, it evaluate the hysteretic behavior of I type strut steel damper with newly designed locking behavior test system based on the results of previous research. The maximum deformation was reached at a horizontal load of 270 kN and a displacement of 25 mm, and the experiment was terminated. The damper installed on the left and right of the panel was also failed. In the future, a performance experiment is being conducted using the strut aspect ratio as a variable.

The flexural strength of lightweight aggregate concrete (LWAC) T-beams reinforced with the minimum amount of longitudinal reinforcement could be conservatively predicted by the conventional procedure using the equivalent stress block specified in concrete code provision.

In this paper, the mechanical properties of GGBFS concrete according to the replacement ratio of electric arc furnace oxidizing slag fine aggregate was evaluated. As the replacement rate of EOS fine aggregate increased, the amount of slump and air content decreased. In addition, EOS concrete increased the initial compressive strength, but, it tended to decrease at 28 days.

In this paper, the mechanical properties of fresh concrete were evaluated by using electric arc furnace oxidizing slag(EOS) aggregate. Water-Cement(W/C) ratio was selected as 0.45 and 0.30, and the mixing amount of EOS aggregate as 0%, 50%, 100%. Experimental items of fresh concrete were slump, flow, air content, unit volume weight. As a results, As the mixing amount of EOS aggregate increased, the slump and flow increased but the air content decreased.