합성보에 휨모멘트가 작용하면, 콘크리트 슬래브의 아랫면과 강재보의 윗면은 각각 인장력과 압축력에 의하여 팽창과 수축을 한다. 필연적으로 두 부재의 사이에서는 미끄러지려고 하는 수평전단력이 작용하게 되며, 이에 저항할 수 있는 전단 연결재의 역할이 매우 중요하다. 이 연구에서는 화약의 폭발력을 사용하여 강재보의 플랜지에 전단연결재를 고정하는 방법을 개발하였다. 개발 고정방법의 구조성능을 검증하기 위하여 보-기둥 접합부 실험과 유한요소해석을 수행하였다. 실험 및 해석결과를 기반으로 판단했을 때, 개발된 접합방식을 통하여 충분한 연성 및 강도를 확보할 수 있을 것으로 판단된다.

Prussian blue is known as a superior material for selective adsorption of radioactive cesium ions; however, the separation of Prussian blue from aqueous suspension, due to particle size of around several tens of nanometers, is a hurdle that must be overcome. Therefore, this study aims to develop granule type adsorbent material containing Prussian blue in order to selectively adsorb and remove radioactive cesium in water. The surface of granular activated carbon was grafted using a covalent organic polymer (COP-19) in order to enhance Prussian blue immobilization. To maximize the degree of immobilization and minimize subsequent detachment of Prussian blue, several immobilization pathways were evaluated. As a result, the highest cesium adsorption performance was achieved when Prussian blue was synthesized in-situ without solid-liquid separation step during synthesis. The sample obtained under optimal conditions was further analyzed by scanning electron microscope-energy dispersive spectrometry, and it was confirmed that Prussian blue, which is about 9.7% of the total weight, was fixed on the surface of the activated carbon; this level of fixing represented a two-fold improvement compared to before COP-19 modification. In addition, an elution test was carried out to evaluate the stability of Prussian blue. Leaching of Prussian blue and cesium decreased by 1/2 and 1/3, respectively, compared to those levels before modification, showing increased stability due to COP-19 grafting. The Prussian blue based adsorbent material developed in this study is expected to be useful as a decontamination material to mitigate the release of radioactive materials.

As a method of seismic-design for pile-supported wharves, equivalent static analysis, response spectrum analysis, and time history analysis method are applied. Among them, the response spectrum analysis is widely used to obtain the maximum response of a structure. Because the ground is not modeled in the response spectrum analysis of pile-supported wharves, the amplified input ground acceleration should be calculated by ground classification or seismic response analysis. However, it is difficult to calculate the input ground acceleration through ground classification because the pile-supported wharf is build on inclined ground, the methods to calculate the input ground acceleration proposed in the standards are different. Therefore, in this study, the dynamic centrifuge model tests and the response spectrum analysis were carried out to calculate the appropriate input ground acceleration. The pile moment in response spectrum analysis and the dynamic centrifuge model tests were compared. As a result of comparison, it was shown that the response spectrum analysis results using the amplified acceleration in the ground surface were appropriate.

Although the 1997 Raw Data of the National Wealth Statistical Survey (South Korea) is timely 20-year-old data, it is meaningful as a benchmarking in the capital stock estimations of Korea, which is estimated by PIM (permanent inventory method). In the case of machinery/equipment, it is the data that can analyze in depth the changes in the industrial structure of Korea. In the case of ASL (average service life) which has economic concept, since the change of ASL is not so large, ASL yielded by the Raw Data of the 1997 National Wealth Statistical Survey is meaningful as reference value for the ASL estimated by the Bank of Korea and the National Statistical Office. As you know Japan has changed its service life due to changes in its industrial structure. However, many of its assets are still used for the years indicated in Showa (before 1989). The same trend with other countries such as Japan. However, the United States is constantly devoted to assessing the useful ASL and value of assets by distinguishing between the Hulten-Wykoff models and those not. Korea has also benchmarked the useful ASL of the United States and Japan when it conducted its own survey every 10 years by due diligence until 1997. In this study, the ‘constraint’ Iowa curve estimation by the Raw Data of the 1997 National Wealth Statistical Survey is based on the age records of the assets and the maximum age of the assets appropriately derived. And then we made modified Iowa curve by smoothing. From this modified one, we suggested ASL by asset. After 1997, the vintage disposal data directly were collected by the National Statistical Office with Oh Hyun Seung, Cho Jin Hyung, in order to estimate the useful ASL. Since then, the B/S team of the Economic and Statistics Bureau of the Bank of Korea has been working on a new concept of content training.

The degree of interaction is a very important factor determining stiffness, strength and deflection performance in the composite beam. Because this synthesis is made through the shear connector, the structural performance of the shear connector is very important. In this study, the connection method was developed using the driving pin to solve the problem of conventional welding connection method. To verify the structural performance of the developed connection method, the push-out test was performed and analyzed against numerical analysis results. Based on the results of the analysis, it is deemed that the structural performance can be obtained by joining the shear connection in proposed method.

Recently, damage to domestic facilities due to strong winds and typhoons is increasing. This study focused on sign structures among various vulnerable facilities. The evaluation of wind fragility was performed considering the destruction of the anchor for fixing, which is one of the failure modes of the sign structures. The performance evaluation of the anchor for fixing was carried out to derive the wind fragility. Three parameters were set and twelve anchor types were selected to perform the pull-out and shear tests. The resistance performance was estimated based on the experimental results. Wind loads were estimated using the Monte Carlo simulation method. Based on this, we derive the wind fragility according to the wind exposure category. Finally, the change of the wind exposure category and the evaluation of the wind fragility according to the experimental parameter were performed.

바이오파울링은 역삼투막 여과 공정에서 운전 성능을 저해하는 주요 원인이다. 이전 연구들은 분리막 표면에 발생하는 바이오파울링을 제어하기 위해서 화학적 세정제를 주입하는 방법을 주로 사용하였다. 화학적 세정제의 주입은 분리막의 손상뿐만 아니라 이차적으로 수계 오염을 발생시키기 때문에 주입 농도와 운영 방법에 주의가 요구된다. 이러한 문제를 극복하기 위해, 본 연구에서는 분리막 표면에 생물막 저해제를 고정하여 바이오파울링을 제어하는 연구를 수행하였다. 표면 고정화를 위한 방법으로 Layer-by-layer 기술을 적용하였고, 생물막저해제로 클로르헥시딘과 글루타알데하이드를 사용하였다. 막 표면의 생물막 저해제 고정화는 미생물의 부착 억제 및 사멸로 생물막 형성이 지연되어 운전 성능이 유지되는 효과를 나타냈다.

In this study, the differences of holding power according to the shape and weight distribution of concrete weight used in shellfish shell fishery were investigated through the experiments. To investigate the differences in shape, five bar-shaped concrete weights with the same length and different cross-sectional shapes were produced. The sectional shape of each weight was square, triangle, circle, small cross, and large cross (SQ, TR, CI, CR-S, CR-L). Ten rectangular parallelepiped weights with different bottom area and cross-sectional area were produced. To investigate the differences by the weight distribution, the holding power on the square model (SQ) with six 50 g weights at different positions was investigated. All the holding power was obtained by measuring the tensile force generated when the concrete weight was pulled at a constant speed on the sand. As a result, there were no differences in holding power between the ten rectangular weights. However, the experiment on weights with different cross-sectional shapes showed differences in holding power. The holding power was higher in the order of CR-L > CR-S > CI > TR > SQ. In the weight distribution test, the holding power was higher as the front side of the weight was heavier. Generally, the frictional force is the same even if the shape is different, when two objects have the same value in the weight and the roughness. On the other hand, it seems to have a large impact when the shape of the bottom is deformed in the course of pulling the object. Particularly, the larger the degree of protrusion like cruciform weights, the more the holding power increased while deeply digging the bottom. It is also likely that the holding power increases as the front weight increases.

In this paper, numerical modeling is conducted to analyze the tension of an anchor line by varying the size and drag coefficient of a buoy when the trapnet is influenced by the wave and the current simultaneously. A mass-spring model was used to analyze the behavior of trapnet underwater under the influence of waves and current. In the simulation of numerical model, wave height of 3, 4, 5 and 6 m, a period of 4.4 s, and the flow speed of 0.7 m/s were used for the wave and current condition. The drag coefficients of buoy were 0.8, 0.4 and 0.2, respectively. The size of buoy was 100, 50 and 25% based on the cylindrical buoy (0.0311 ㎥) used for swimming crab trap. The drag coefficient of the trapnet, the main model for numerical analysis, was obtained by a circular water channel experiment using a 6-component load cell. As a result of the simulation, the tension of the anchor line decreased proportional to buoy’s drag coefficient and size; the higher the wave height, the greater the decrease rate of the tension. When the buoy drag coefficient and size decreased to one fourth, the tension of the anchor line decreased to a half and the tension of the anchor line was lower than the holding power of the anchor even at 6 m of wave height. Therefore, reducing the buoy drag coefficient and size appropriately reduces the trapnet load from the wave, which also reduces the possibility of trapnet loss.

In the present study, sled analysis was conducted under the condition of 20g (20 times of gravitational acceleration) and 48 km/h of initial velocity, suggested by WC-19 to investigate the injuries of traffic minorities of tie-down type fixing inside a vehicle during crash. Also, four new parameters, which were related to angles between belts and wheelchair and their levels were limited by WC-19, were proposed and orthogonal array was prepared with different levels of each parameter. In the meantime, four parameters were optimised by minimising head injury criteria and chest acceleration of passengers in each case of the orthogonal array.

This study introduces the comparison of efficiency levels of photovoltaics systems by analyzing various installation systems of photovoltaics systems and optimization techniques and proposes a system using techniques In this study, the generation time and power generation of two types of photovoltaic power generation system were measured and compared. Comparing the monthly power generation time with the power generation amount, it is found that there are many fixed variable photovoltaic power generation systems with a large average daily power generation time of 0.8h and an average power generation capacity of 2,871kw from November to December. Total Fixed Variable Total Daily Power Generation Time 2.4h The power generation amount is 23,184kw, showing a large amount of electric power generation.

In order to study the effect of barley, Italian ryegrass (IRG), and legume mixture on nitrogen fixation and transfer to grasses on spring paddy field, an experiment was carried out from Oct. 2006 to June 2007 in Naju, Korea. A split plot design with three replications was used for the experiment. One reference plot was assigned for each treatment to determine nitrogen fixation. Main plots consisted of Chinese milk vetch, crimson clover, forage pea, and hairy vetch with barley, respectively. Subplot treatment were barley or IRG with four seeding ratio of legumes (50:50, 60:40, 70:30, and 80:20). To estimate N fixation by legumes, 15N isotope dilution technique was used. 15N fertilizer [(15NH4)2SO4 solution at 99.8 atom N] was uniformly applied to 600 cm2 in the middle of each plot on April 15, 2007. Plots were harvest by hand on June 8, 2007. Dried sample were ground to a fine power and analyzed for total N isotope N. 15N was determined using elemental analyzer-isotope ratio mass spectrometry. The calculation of N transfer was determined with the isotope dilution method. The content of N was higher in legumes than that in barley or Italian ryegrass. Nitrogen level in forage pea was significantly higher than that of other legumes. There were significantly differences in N content between legumes in IRG mixture. Atom % 15N excess was significantly different in legumes with barley. The 60:40 sub plot had higher (p<0.05) atom % 15N than other seeding ratio treatments. The enrichment ranged from 0 to 0.58. Compared to barley, the enrichment of IRG with its accompanied legumes was higher, ranging from 0.38 to 1.0. The N derived from the atmosphere (Ndfa) ranged from 0% to 49.5% with barley-legume mixture. It ranged from 0 to 60.5% in IRG-legume plots. N transfer from legumes to neighboring grasses was 12.3 to 90.9 kg/ha for barley-legume mixture and 31.7 to 107.8 kg/ha for IRG plots. IRG plots showed higher N transfer for IRG-legume mixture in general based on difference method. Based on 15N dilution method, the N transfer was 0 to 36.1 kg/ha for barley-legume mixture and 0 to 50.6 kg/ha for IRG plots. There was a tendency toward higher N transfer on the difference method than that of the 15N dilution method.

One of the important advantages of Thermosonics is that it can be applied to complex structures such as a turbine blade as a convenient and quick screening test method. For a reliable thermosonic test, the vibrational characteristics of the system comprising the tested structure and the clamp at ultrasonic frequency range should be identified. Therefore, this study presented the analysis results of frequency response functions and mode shapes of the turbine blade and clamp system and investigate the possibility of the reliable excitation system for the thermosonic test.

With increasing demands of transportation services for disabled or aged people, who need wheelchairs, it is recommended to install wheelchairs inside automotive vehicles. However, wheelchairs are not effectively safe devices during car crash unless they are properly fixed. So far, few data have been found related to wheelchair safety or characteristics during car crash, therefore, frontal crash simulations have been carried out based on the FE models of a dummy and a conventional wheelchair including the wheelchair fixing belts and the install plate in the present study. Head injury criteria (HIC) and motion criteria (MC) are investigated and the optimum value of the design variable was found by the Robust design.

The mobility of the tactical vehicle is important for a mission completion and survivability. During the field operation of the MLRS(Multiple Launcher Rocket System), broken bolt was found in a final reduction gear with oil leakage. It was confirmed that the final reduction gear pad bolt was broken with ductile fracture after inspecting and scanning electronic microscope of the bolt. Furthermore, a finite element analysis on the bolt was conducted with regards to the operating conditions in the final reduction gear. Conducting the analysis, there was a possibility of the bolt being damaged when we put rusty spline and the adhesion of hub thrust pad as input parameters. Finally, improvements on the spline in the shaft are expected in the future by utilizing the result of this study.