Scanning probe microscopy (SPM) has become an indispensable tool in efforts to develop the next generation of nanoelectronic devices, given its achievable nanometer spatial resolution and highly versatile ability to measure a variety of properties. Recently a new scanning probe microscope was developed to overcome the tip degradation problem of the classic SPM. The main advantage of this new method, called Reverse tip sample (RTS) SPM, is that a single tip can be replaced by a chip containing hundreds to thousands of tips. Generally for use in RTS SPM, pyramid-shaped diamond tips are made by molding on a silicon substrate. Combining RTS SPM with Scanning spreading resistance microscopy (SSRM) using the diamond tip offers the potential to perform 3D profiling of semiconductor materials. However, damage frequently occurs to the completed tips because of the complex manufacturing process. In this work, we design, fabricate, and evaluate an RTS tip chip prototype to simplify the complex manufacturing process, prevent tip damage, and shorten manufacturing time.

The aim of this study is to ensure the structural integrity of a canister to be used in a dry storage system currently being developed in Korea. Based on burnup and cooling periods, the canister is designed with 24 bundles of spent nuclear fuel stored inside it. It is a cylindrical structure with a height of 4,890 mm, an internal diameter of 1,708 mm, and an inner length of 4,590 mm. The canister lid is fixed with multiple seals and welds to maintain its confinement boundary to prevent the leakage of radioactive waste. The canister is evaluated under different loads that may be generated under normal, off-normal, and accident conditions, and combinations of these loads are compared against the allowable stress thresholds to assess its structural integrity in accordance with NUREG-2215. The evaluation result shows that the stress intensities applied on the canister under normal, off-normal, and accident conditions are below the allowable stress thresholds, thus confirming its structural integrity.

A transfer cask serves as the container for transporting and handling canisters loaded with spent nuclear fuels from light water reactors. This study focuses on a cylindrical transfer cask, standing at 5,300 mm with an external diameter of 2,170 mm, featuring impact limiters on the top and bottom sides. The base of the cask body has an openable/closable lid for loading canisters with storage modules. The transfer cask houses a canister containing spent nuclear fuels from lightweight reactors, serving as the confinement boundary while the cask itself lacks the confinement structure. The objective of this study was to conduct a structural analysis evaluation of the transfer cask, currently under development in Korea, ensuring its safety. This evaluation encompasses analyses of loads under normal, off-normal, and accident conditions, adhering to NUREG-2215. Structural integrity was assessed by comparing combined results for each load against stress limits. The results confirm that the transfer cask meets stress limits across normal, off-normal, and accident conditions, establishing its structural safety.

본 연구는 EMG(electromyography) 텍스타일 전극 개발을 목적으로 레이어 수의 디자인 및 원단을 다르게 하여 성능 및 신호 획득 안정성을 평가한다. 레이징 및 프레스 공정을 통하여 텍스타일 전극을 제조하며 Layer-0, Layer-1, Layer-2로 레이어 유무 및 수에 따른 결과를 분석했다. 이에 레이어 유무에 따라서는 근활성 측정에 영향을, 수가 많을수록 높은 성능이 나타남을 확인할 수 있었다. Layer-2 구조로 통일하여 5가지의 원단(네오프렌, 스판덱스 쿠션, 폴리에스테르 100%, 나일론 스판덱스, 광목 캔버스)으로 전극을 제조해 실험해 보았다. 성능적인 면에서, 원단의 중 량이 높은 나일론 스판덱스가 높은 성능을 보였으며, 스판쿠션 텍스타일 전극이 근활성도 수득에 높은 안정성을 보 였다. 이에 위 연구는 레이어에 따른 성능 연관성과 전극-피부사이의 닿는 면적 간의 관계 등을 고찰하여 슬리브 전체의 의복압을 늘리는 대신 특정 센서 측정 부위에만 높은 압력을 가함으로 차후 연구에서 레이어의 수 및 물성에 따른 전극의 공학적 설계 가능성을 제시한 의의가 있다.

For efficient design and manufacture of PWR spent fuel burnup detector, data simulated with various condition of spent fuel in the NPP storage pool is required. In this paper, to derive performance requirements of spent fuel burnup detector for neutron flux and dose rates were evaluated at various distances from CE16 and WH17 types of fuel, representatively. The evaluation was performed by the following steps. First, the specifications of the spent fuel, such as enrichment, burnup, cooling time, and fuel type, were analyzed to find the conditions that emit maximum radioactivity. Second, gamma and neutron source terms of spent fuel were analyzed. The gamma source terms by actinides and fission products and neutron source terms by spontaneous and (α, n) reactions were calculated by SCALE6 ORIGAMI module. Third, simulation input data and model were applied to the evaluation. The material composition and dose conversion factor were referred as PNNL-15870 and ICRP-74 data, respectively and dose rates were displayed with the MCNP output data. It was assumed that there was only one fuel modeled by MCNP 6.2 code in pool. The evaluation positions for each distance were selected as 5 cm, 10 cm, 25 cm, 50 cm, and 1 m apart from the side of fuel, respectively. Fourth, neutron flux and dose rates were evaluated at distance from each fuel type by MCNP 6.2 code. For WH 17 types with a 50 GWd/MTU burnup from 5 cm distance close to fuel, the maximum neutron flux, gamma dose rates and neutron dose rates are evaluated as 1.01×105 neutrons/sec, 1.41×105 mSv/hr and 1.61×101 mSv/hr, respectively. The flux and dose rate of WH type were evaluated to be larger than those of CE type by difference in number of fuel rods. The relative error for result was less than 3~7% on average secured the reliability. It is expected that the simulated data in this paper could contribute to accumulate the basic data required to derive performance requirements of spent fuel burnup detector.

In the wake of the Fukushima NPP accident, research on the safety evaluation of spent fuel storage facilities for natural disasters such as earthquakes and tsunamis has been continuously conducted, but research on the protection integrity of spent fuel storage facilities is insufficient in terms of physical protection. In this study, accident scenarios that may occur structurally and thermally for spent fuel storage facilities were investigated and safety assessment cases for such scenarios were analyzed. Major domestic and international institutions and research institutes such as IAEA, NEA, and NRC provide 13 accident scenario types for Spent Fuel Pool, including loss-of-coolant accidents, aircraft collisions, fires, earthquakes. And 10 accident scenario types for Dry Storage Cask System, including transportation cask drop accidents, aircraft collisions, earthquakes. In the case of Spent Fuel Pool, the impact of the cooling function loss accident scenario was mainly evaluated through empirical experiments, and simulations were performed on the dropping of spent nuclear fuel assembly using simulation codes such as ABAQUS. For Dry Storage Cask System, accident scenarios involving structural behavior, such as degradation and fracture, and experimental and structural accident analyses were performed for storage cask drop and aircraft collision accidents. To evaluate the safety of storage container drop accidents, an empirical test on the container was conducted and the simulation was conducted using the limited element analysis software. Among the accident scenarios for spent fuel storage facilities, aircraft and missile collisions, fires, and explosions are representative accidents that can be caused by malicious external threats. In terms of physical protection, it is necessary to analyze various accident scenarios that may occur due to malicious external threats. Additionally, through the analysis of design basis threats and the protection level of nuclear facilities, it is necessary to derive the probability of aircraft and missile collision and the threat success probability of fire and explosion, and to perform protection integrity evaluation studies, such as for the walls and structures, for spent fuel storage facilities considering safety evaluation methods when a terrorist attack occurs with the derived probability.

In an automotive plant, an automated storage and retrieval system (ASRS) synchronizes material handling flows from a part production line to an auto-assembly line. The part production line transfers parts on small-/large-sized pallets. The products on pallets are temporarily stored on the ASRS, and the ASRS retrieves the products upon request from the auto-assembly line. Each ASRS aisle is equipped with narrow-/wide-width racks for two pallet sizes. An ASRS aisle with narrow-/wide-width racks improves both storage space utilization and crane utilization while requiring delicate ASRS aisle design, i.e., the locations of the narrow-/wide-width racks in an ASRS aisle, and proper operation policies affect the ASRS performance over demand fluctuations. We focus on operation policies involving a common storage zone using wide-width racks for two pallet sizes and a storage-retrieval job-change for a crane based on assembly-line batch size. We model a discrete-event simulation model and conduct extensive experiments to evaluate operation policies. The simulation results address the best ASRS aisle design and suggest the most effective operation policies for the aisle design.

로터 블레이드는 조류발전 터빈의 매우 중요한 구성 요소로서, 해수의 높은 밀도로 인해 큰 추력(Trust force)와 하중(Load)의 영 향을 받는다. 따라서 블레이드의 형상 및 구조 설계를 통한 성능과 복합소재를 적용한 블레이드의 구조적 안전성을 반드시 확보해야 한 다. 본 연구에서는 블레이드 설계 기법인 BEM(Blade Element Momentum) 이론을 이용해 1MW급 대형 터빈 블레이드를 설계하였으며, 터빈 블레이드의 재료는 강화섬유 중의 하나인 GFRP(Glass Fiber Reinforced Plastics)를 기본으로 CFRP(Carbon Fiber Reinforced Plastics)를 샌드위치 구조에 적용해 블레이드 단면을 적층(Lay-up)하였다. 또한 유동의 변화에 따른 구조적 안전성을 평가하기 위해 유체-구조 연성해석 (Fluid-Structure Interactive Analysis, FSI) 기법을 이용한 선형적 탄성범위 안의 정적 하중해석을 수행하였으며, 블레이드의 팁 변형량, 변형 률, 파손지수를 분석해 구조적 안전성을 평가하였다. 결과적으로, CFRP가 적용된 Model-B의 경우 팁 변형량과 블레이드의 중량을 감소시 켰으며, 파손지수 IRF(Inverse Reserce Factor)가 Model-A의 3.0*Vr를 제외한 모든 하중 영역에서 1.0 이하를 지시해 안전성을 확보할 수 있었 다. 향후 블레이드의 재료변경과 적층 패턴의 재설계뿐 아니라 다양한 파손이론을 적용해 구조건전성을 평가할 예정이다.

최근 토목공학 분야 내 현장조건을 구현할 수 있는 스마트 건설 기술의 요소기술로서 3D 프린팅 기술의 적용 분야 가 확대되고 있다. 센서기술의 보조도구, 모듈러 시공상 적용 등으로 다양하게 활용되고 있는 가운데 3D 프린팅 기술을 단순 부재 제작이 아닌 각각의 부재들이 최대 성능을 발휘할 수 있는 최적설계 도출 방안으로 활용하고자 한다. 이를 위해 3D 프린 팅 재질인 필라멘트를 활용하더라도 신뢰성 있는 최적설계가 도출이 가능한지에 대한 연구가 선행되어야 하며, 이에 본 연구에 서는 지반보강재 중 하나인 지오셀 관련 선행연구 결과와 필라멘트의 물성치가 적용된 해석 결과와의 비교를 통해 재료적 신뢰 성을 검증하고자 한다. 해석 결과, 지오셀 구성요소에 따른 보강성능의 경향이 기존 선행연구 결과와 일치함을 확인하였기에 필 라멘트를 활용하더라고 충분히 신뢰성 있는 최적설계가 도출이 가능할 것이라 판단된다.

New buildings have been designed using different seismic design standards that have been revised. However, the seismic performance of existing buildings is evaluated through the same performance evaluation guidelines. Existing buildings may not satisfy the performance targets suggested in the current guidelines, but there are practical limitations to discriminating the existing buildings with poor seismic performance through a full investigation. In this regard, to classify buildings with poor seismic performance according to the applied standard, this study aimed to evaluate performance-based investigation of the seismic design proposals of buildings with different design standards. The target buildings were set as RC ordinary moment frames for office occupancy. Changes in seismic design criteria by period were analyzed, and the design spectrum changes of reinforced concrete ordinary moment resisting frames were compared to analyze the seismic load acting on the building during design. The seismic design plan was derived through structural analysis of the target model, compared the member force and cross-sectional performance, and a preliminary evaluation of the seismic performance was performed to analyze the performance level through DCR. As a result of the seismic performance analysis through the derived design, the reinforced concrete ordinary moment frame design based on AIK 2000 has an insufficient seismic performance level, so buildings built before 2005 are likely to need seismic reinforcement.

PURPOSES : This study evaluates the long-term performance of the asphalt overlay designed by the Seoul pavement design method which determines overlay thickness by considering existing pavement conditions, traffic volume, and bearing capacity of the pavement. METHODS : A total of 76 sections including 17 control sections and 59 design sections were constructed under various traffic conditions, overlay thicknesses and asphalt mixtures. The performance of the pavements has been monitored up to 60 months in terms of surface distresses, rutting, and longitudinal roughness. The service life of the pavements was estimated to be the period when the Seoul pavement condition index (SPI) becomes 6.0, i.e., a rehabilitation level. RESULTS : Overall, the service life of the pavements was 72 months in the control and 120 months for the design sections. For relatively thinner overlay sections than designed, the service life reduced significantly; 36 months for 15cm thick overlay and 120 months for 25cm thick overlay. The service life of the pavement in the bus-only lane was 78 months, which is 30 months shorter than that in mixed-traffic lanes. Out of the bus-only lanes, 56% of the pavement along bus stop was deteriorated early to be a poor condition while only 2% of the pavement in a driving lane was degraded to be poor. The overlay with Stone Mastic Asphalt (SMA) in the wearing surface had 38% longer life than that with conventional dense graded mixtures. CONCLUSIONS : Most of the overlays sections designed by the Seoul pavement design method were expected to survive 10 years, except for bus-only lanes. The control sections having 5 to 10 cm thick overlays showed significant lower performance than the design sections. Thus proper thickness and materials considering the characteristics of existing pavement and traffic volumes should be applied to secure the service life of overlays.

Due to the Fukushima nuclear accident, a large amount of radioactive material was released into the atmosphere, and consequently, it spread over a wide area and was deposited into the soil. As a result of this, a wide area of radioactive contamination site was created. Due to the contaminated site, the need for research on various exploration platforms for efficient situation management and field response is being emphasized. Backpack-type radiation survey & monitoring equipment is useful for creating a contamination maps containing information such as Dose Rate, Radionuclide, Activity Concentration accompanied by spatial analysis when performing a Scan Survey that moves with a backpack on a wide area site. contamination maps are based on accurate radiological characteristic information. However, there is a problem in that the accuracy of the evaluation results is lowered due to changes in environment conditions or the variability of the dose rate and counting rate during scan survey. This problem should be solved by applying the influence of each variable to the underlying data. However, prior to this, it is most important to prepare the base underlying first. And this can be obtained through evaluation of detection performance through static survey. Therefore, in this study, the change in detection efficiency for the measurement height and radius of the backpack-type radiation survey & monitoring equipment based on the 3"×3" NaI(Ti) detector was evaluated. First, the height of the source and Backpack-type radiation survey & monitoring equipment was evaluated from 0 cm to 1 m, which is the height of the soil and detector when an adult male wears a backpack. The experiment was conducted using the 137Cs (383 kBq) point source, which is a nuclide mainly detected at the contaminated site. The measurement time was measured five times per one minute, considering that it was backpack-type equipment and a future scan survey. In addition, in order to evaluate the detection radius, the measurement was performed by changing the measurement distance up to 5 m at intervals of 50 cm. As a result of evaluating the detection performance of the backpack-type radiation surveys & monitoring equipment, it was confirmed that increasing the detection height and radius reduces the count rate in the form of an exponential function. In addition, it was confirmed that the detected radius varies depending on the height. Based on these results, we plan to conduct additional research to understand the scan survey and its sensitivity to various factors. Through this, the company plans to develop various models for exploring the site by improving the accuracy of backpack-type radiation surveys & monitoring equipment.

Seismic demand on nonstructural components (NSCs) is highly dependent on the coupled behavior of a combined supporting structure- NSC system. Because of the inherent complexities of the problem, many of the affecting factors are inevitably neglected or simplified based on engineering judgments in current seismic design codes. However, a systematic analysis of the key affecting factors should establish reasonable seismic design provisions for NSCs. In this study, an idealized 2-DOF model simulating the coupled structure-NSC system was constructed to analyze the parameters that affect the response of NSCs comprehensively. The analyses were conducted to evaluate the effects of structure-NSC mass ratio, structure, and NSC nonlinearities on the peak component acceleration. Also, the appropriateness of component ductility factor (R p) given by current codes was discussed based on the required ductility capacity of NSCs. It was observed that the responses of NSCs on the coupled system were significantly affected by the mass ratio, resulting in lower accelerations than the floor spectrum-based response, which neglected the interaction effects. Also, the component amplification factor (a p) in current provisions tended to underestimate the dynamic amplification of NSCs with a mass ratio of less than 15%. The nonlinearity of NSCs decreased the component responses. In some cases, the code-specified R p caused nonlinear deformation far beyond the ductility capacity of NSCs, and a practically unacceptable level of ductility was required for short-period NSCs to achieve the assigned amount of response reduction.

In this study, stiffness evaluation was conducted on the main member, front cross member, and rear cross member, which are three components of sub-frame for SUVs (sports utility vehicles), through mode analysis. As for the design variables used in the analysis, the maximum frequency was examined by varying the width and height of each of the three parts into four types. Of course, the weight at this time is minimized, and the mode is set as a constraint that only bending occurs and no distortion occurs. As a result of the analysis, the member affecting the 1st mode was the rear cross member, and the member having the greatest influence on the 2nd mode was the front cross member. In addition, the member with the greatest influence on the 3rd mode appeared as the rear cross member, indicating that this part had the greatest effect on the bending stiffness.

In this paper, the flexural capacity equation of FRP-bar reinforced concrete beams was verified by comparing the experimental results and flexural capacity obtained according to the ACI procedure. And, also the economic feasibility of FRP-bar reinforced concrete beams was analyzed by comparing nominal moment capacity of beams. The results of analysis were as follows, 1) GFRP concrete beams have lower flexural performance than reinforced concrete beams, whereas CFRP concrete beams have similar flexural performance to reinforced concrete beams under the same reinforcement ratio 2) Although the design moment increased as the compressive strength of concrete increased, the flexural performance of GFRP reinforced concrete beams was found to be lower than the reinforced concrete beams for all reinforcement ratios.

최근 비구조요소의 피해사례가 증가하면서 비구조요소 내진설계에 관한 많은 연구가 진행되고 있다. 하지만 대부분의 연구는 평면 적 요소보다는 수직적 요소나 시스템적 요소를 변수로 층가속도를 평가하고 있다. 때문에 본 논문에서는 횡력저항에 많은 부분을 차 지하는 코어를 평면적 변수로 사용하여 비구조요소 내진설계를 위한 층가속도에 대해 평가하였다. 정사각형의 2축대칭의 평면에서 코어의 형태(위치 및 비중)변화에 따라 서로 다른 5개의 평면과 각 평면마다 5층, 10층, 15층, 20층의 층수를 가진 총 20개의 모델로 선 형시간이력해석을 수행하였다. 분석 결과 코어 위치에 따라 편심을 받는 평면에서는 층가속도가 최대 1.7배의 비틀림 증폭이 발생하 였고 구조물의 중층부에서 비틀림의 영향이 가장 큰 것을 확인할 수 있었다. 편심이 없이 코어의 비중만 변화한 평면에서는 주기 0.4694초를 기준으로 이하일 때는 주기가 증가할수록 층가속도가 저층부에서는 감소하고 고층부에는 증가하며, 반대로 주기 0.4694 초 이상일 때는 주기가 증가할수록 층가속도가 저층부에서는 증가하고 고층부에는 감소한다는 것을 확인할 수 있었다. 또한, 구조물 의 층수는 최대층가속도에 영향을 주지 못하는 것을 확인하였다. 핵심용어 :