전 세계 각국은 탄소 배출량을 줄이기 위한 다양한 노력을 하고 있다. 지난 수십 년간 몇몇 연구자들은 탄소배출량 을 줄이기 위해서 철근콘크리트 구조에서 철근을 FRP로 대체하기 위한 연구를 수행해 왔다. FRP보강근을 휨부재로 사용하기 위한 연구는 많이 수행되어 왔으나, FRP 보강근 기둥의 성능을 평가하고 설계하기 위한 연구는 거의 이루어지지 않았다. 본 연 구는 FRP보강근 콘크리트 구조 기둥과 철근콘크리트 기둥의 P-M 상관도를 비교하고, 철근콘크리트 기둥에서 철근의 대체재로 서 FRP보강근의 활용 가능성을 제시하였고, 변수는 콘크리트의 압축강도, FRP보강근의 종류, 보강근비이다.철근을 GFRP로 대체 할 경우, 요구 GFRP 보강근의 양은 철근의 4배이며, 철근비가 4% 이상이면 동일한 단면으로는 설계할 수 없다. 편심거리비가 1.0보다 크거나 철근비가 4%보다 작은 철근콘크리트 기둥의 철근을 CFRP로 대체할 경우, 보강근의양을 1/2수준으로 줄이거나 단면 크기를 줄일 수 있다.

The buffer block, which is one of the main components of the engineering barrier system, plays an essential role in mitigating groundwater infiltration and radionuclide transport in a high-level nuclear waste repository. To achieve those purposes, the compacted buffer block must satisfy the functional safety criteria for dry density, water content, and many other components. In this study, the compation curves of the compacted bentonite-sand mixtures were evaluated to identify the relationship between the dry density and the water content of the buffer material. The floating die press at 10 MPa and the cold isostatic press at 40 MPa were applied to compaction of a buffer block with a diameter of 100 mm and a thickness of 10 mm. The condition of a bentonite-sand mixing ratio was 6:4, 7:3, 8:2, and 9:1 with 9 to 21% water content. As a result, the maximum dry density increases, the optimum moisture content decreases as the sand content of buffer material increases. This study can provide the conditions for manufacturing the compacted bentonite-sand buffer block.

PURPOSES : The purpose of this study is to disseminate the process of deriving the truck performance curve of Korea’s representative trucks in detail such that the relevant experts can use it in the future when re-selecting the representative trucks and deriving the truck performance curve accordingly. METHODS : To collect relevant data required to derive the truck performance curve, this study used four trucks that implemented the weight/power of the nation’s representative trucks, and conducted a practical driving test on four different upgrade sections. RESULTS : The truck performance curve was derived for each driving position to represent the deceleration and acceleration capabilities of the truck through the actual driving test on the upgrade sections. CONCLUSIONS : The truck performance curve derived from this study indicated that the truck’s deceleration and acceleration capabilities increased as the total weight/power of Korea’s representative trucks improved, and the design of the climbing lane demonstrated that the design method used in this study saved approximately 60% of the construction cost compared to the existing method.

The method of evaluating the forming limit of sheet metal is using the forming limit diagram(FLD), and the test method for measuring forming limit curve(FLC) is ISO standardized. On the other hand, in the case of metal bulk materials, it was confirmed that the forming limit was defined by using various predictive models based on the ductile fracture theory. However it did not show a constant forming limit (limit damage value) depending on the shape of the specimen. Therefore, a study was conducted on the derivation of the triaxial stress curve to predict the fracture of the material for various stress triaxiality, not the existing limit damage value.

For the important safety system, two or more units of identical equipment or redundant components with similar function were installed to prevent abnormal failure. If the failure probability of such equipment is independent, this redundancy could increase the system safety remarkably. However, if the failure of each component is highly correlated by installing in a structure or experiencing an earthquake event, the expected redundancy effect will decrease. Therefore, the seismic correlation of the equipment should be evaluated quantitatively for the seismic probabilistic safety assessment. The correlation effect can be explained in the procedure of constructing fragility curves. In this study, several methodologies to quantify the seismic correlation in the failure probability calculation for multiple components were reviewed and two possible ways considering the realistic situation were selected. Simple examples were tested to check the applicability of these methods. The conversion method between these two methods was suggested to render the evaluation using the advantages of each method possible.

군락 광합성 모델의 도출을 위하여 생육 챔버가 필요하며, 이를 위한 광합성의 효율적인 측정 방법이 필요하다. 본 연구의 목적은 내부 환경 제어가 가능한 생육 챔버를 이용하여 광도 및 이산화탄소 농도 변수를 갖는 로메인 상추(Lactuca sativa L.)의 군락 광합성 곡선을 도출하는 방법을 확립하는 것이다. 실험에 사용한 상추는 식물공장 모듈에서 재배되었으며, 군락 광합성을 측정하기 위하여 아크릴로 제작된 생육 챔버(1.0x0.8x0.5m)를 이용하였다. 첫 번째로, 다음의 두 방법을 적용하여 측정된 군락 광합성 속도를 통해 각 방법의 시정수를 계산하여 비교하였다. 즉, 1) CO2 농도를 고정(1,000μmol·mol-1) 하고 광도를 변화(340, 270, 200, and 130μmol·m-2·s-1) 시키거나, 2) 광도를 고정(200μmol·m-2·s-1)하고 CO2 농도를 변화(600, 1,000, 1,400, and 1,800μmol·mol-1) 시켰다. 두 번째로, 1)과 2)의 방식을 적용하여 군락 광합성을 측정했을 때, 특정 광도(200μmol·m-2·s-1)와 특정 CO2 농도(1,000μmol·mol-1)에서 측정된 군락 광합성 속도 값을 비교하였다. 실험 결과 CO2 농도를 변화시키는 방식의 시정수는 광도를 변화시키는 방식에 비해 3.2배 큰 값을 나타내었다. 광도를 변화시키며 측정할 때 군락 광합성 속도는 1분 이내에 안정되었고, CO2 농도를 변화시킬 경우에는 6분 이상의 시간이 소요되었다. 따라서 광도를 변화시키는 측정 방식이 생육 챔버를 이용하여 작물의 군락 광합성 속도를 측정할 때 적합한 방식임을 확인하였다.

The prediction of Jominy hardness curves and the effect of alloying elements on the hardenability of boron steels (19 different steels) are investigated using multiple regression analysis. To evaluate the hardenability of boron steels, Jominy end quenching tests are performed. Regardless of the alloy type, lath martensite structure is observed at the quenching end, and ferrite and pearlite structures are detected in the core. Some bainite microstructure also appears in areas where hardness is sharply reduced. Through multiple regression analysis method, the average multiplying factor (regression coefficient) for each alloying element is derived. As a result, B is found to be 6308.6, C is 71.5, Si is 59.4, Mn is 25.5, Ti is 13.8, and Cr is 24.5. The valid concentration ranges of the main alloying elements are 19 ppm < B < 28 ppm, 0.17 < C < 0.27 wt%, 0.19 < Si < 0.30 wt%, 0.75 < Mn < 1.15 wt%, 0.15 < Cr < 0.82 wt%, and 3 < N < 7 ppm. It is possible to predict changes of hardenability and hardness curves based on the above method. In the validation results of the multiple regression analysis, it is confirmed that the measured hardness values are within the error range of the predicted curves, regardless of alloy type.

본 연구는 체성숙이 완료된 15개월령 이상의 한우 암소로부터 초음파 측정 장치를 활용하여 조사된 등지방두께(UBF), 배장근단면적(UEMA), 근내지방도(UMS)의 형질들에 대한 유전능력을 추정하기 위한 통계분석방법을 도출하기 위한 연구로써 신체충실지수 및 월령에 대한 사전 보정의 효율성을 알아보고 유전평가를 위한 형질별 유전모수를 추정함으로써 유전능력 추정의 효율성을 향상하기 위한 방안을 도 출하고자 실시하였다. 분석에 이용된 자료는 2001년부터 전국의 1,004농가에서 사육중인 15개월령 이 상의 한우 암소 38,663두로부터 조사된 초음파 측정 육질관련 형질들에 대하여 조사된 자료를 이용하였다. 흉위 및 도축형질들에 대한 성장곡선함수식을 추정하기 위하여 농가-년-월(HYM) 및 신체충실지 수(BCS)에 대한 통계모형식을 통하여 사전보정을 실시하고 Von Bertalanfy함수식을 이용한 비선형 성장곡선 함수식을 추정하였다. 또한 도축형질들에 대하여 개체별로 조사된 관측치는 성장곡선 함수식에 대한 편차로 자료변환한 후에 유전모수를 추정한 결과, 각 형질별 유전력은 UBF에서 0.29, UEMA는 0.56 및 UMS에서 0.49의 추정치를 보였다.

PURPOSES: The purpose of this research is to analyze the characteristics of panels that affect the evaluating results of riding quality and to evaluate the appropriateness of roughness management criteria based on ride comfort satisfaction. METHODS: In order to analyze the influence of panel characteristics of riding quality, 33 panels, consisting of civilians and experts, were selected. Also, considering the roughness distribution of the expressway, 35 sections with MRI ranging from 1.17 m/km to 4.65 m/km were selected. Each panel boarded a passenger car and evaluated the riding quality with grades from 0 to 10, and assessed whether it was satisfied or not. After removing outlier results using a box plot technique, 964 results were analyzed. An ANOVA was conducted to evaluate the effects of panel expertise, age, driving experience, vehicle ownership, and gender on the evaluation results. In addition, by using the receiver operating characteristics (ROC) curve, the MRI value, which can most accurately evaluate the satisfaction with riding quality, was derived. Then, the compatibility of MRI was evaluated using AUC as a criterion to assess whether the riding quality was satisfactory. RESULTS: Only the age of the panel participants were found to have an effect on the riding quality satisfaction. It was found that satisfaction with riding quality and MRI are strongly correlated. The satisfaction rate of roughness management criteria on new (MRI 1.6 m/km) and maintenance (MRI 3.0 m/km) expressways were 95% and 53%, respectively. As a result of evaluating the roughness management criteria by using the ROC curve, it was found that the accuracy of satisfaction was the highest at MRI 3.1-3.2 m/km. In addition, the AUC of the MRI was about 0.8, indicating that the MRI was an appropriate index for evaluating the riding quality satisfaction. CONCLUSIONS: Based on the results, the distribution of the panels’age should be considered when panel rating is conducted. From the results of the ROC curve, MRI of 3.0 m/km, which is a criterion of roughness management on maintenance expressways, is considered as appropriate.

δ Scuti형 변광성 BO Lyn의 파장에 따른 광도곡선 차이를 알아보기 위해서 보현산천문대의 1.8m 반사망원경과 적외선 검출기 KASINICS를 이용한 측광 관측을 수행하였다. 2011년 3월 26일부터 4월 1일까지 총 7일간의 관측 자료 로 J, H, Ks필터 광도곡선을 얻어 기존에 보고된 V필터에서의 광도곡선과 비교하여 주기, 극대점, 진폭, 형태에 대한 차이를 알아보았다. 적외선 광도곡선의 주기 분석 결과 단일 주파수해 f1=10.712 cycle/day, 주기 P=0.09335±0.00002 days의 값을 얻었으며, 파장에 따른 주기의 차이는 나타나지 않았다. 적외선에서는 2f1에 해당하는 주파수가 검출되었는 데, 이는 고진폭 δ Scuti형 변광성의 특징인 비대칭적인 광도곡선의 형태를 잘 설명해준다. 극대점의 위치를 비교한 결 과 계산된 V필터의 예상 극대점보다 관측된 적외선 극대점이 전체 주기의 약 0.3에 해당하는 만큼 더 늦게 나타났다. 진폭은 ΔJ/ΔV=0.328, ΔH/ΔV=0.216, ΔKs/ΔV=0.211로 파장이 길어질수록 변광의 폭이 더 작게 나타났다. 파장에 따른 극대점의 지연과 변광폭의 차이는 맥동변광성의 밝기 변화가 주로 온도변화에 기인하기 때문인 것으로 여겨진다.