압축하중을 받는 콘크리트 충전 강관(CFT) 부재는 강관에 의한 심부구속효과로 인해 내부 콘크리트의 취성이 감소하며, 이는 CFT 부재의 압축강도를 크게 증가시킨다. 본 연구에서는 강관을 퍼포본드 리브 전단연결재로 보강하여 콘크리트의 심부구속효과를 향상 시키고, 유한요소해석 모델에서 재료 특성 및 경계 조건을 설정하여 이를 평가하였다. 이때, 강재와 콘크리트 사이의 계면 거동을 보 다 정확하게 모사하기 위해 cohesive element를 사용하였으며, 이를 통해 강관과 콘크리트 간 하중 전달을 모델링하였다. 전단연결재 로 인한 심부구속효과 향상을 검증하기 위해 퍼포본드 리브 전단연결재가 적용된 CFT 부재의 축소 모델에 대한 실험 및 유한요소해 석을 수행하였고, 전단연결재가 없는 CFT 부재와의 비교를 통해 성능 향상이 확인되었다. 퍼포본드 리브 전단연결재는 홀의 지름 및 개수를 변화시키며 파라미터 스터디를 수행하였고, 이로 인해 전단연결재의 전단저항력 변화가 심부구속효과에 미치는 영향에 대해 평가하였다. 전단연결재의 전단저항력 변화에 따른 CFT 부재의 구조적 성능 차이를 분석하면서, 실험과 유한요소해석의 일치성을 검토하였다.

This study is to deal with the cause analysis and improvement ideas for breakage to hydraulic pipes mounted on self-propelled howitzers. Hydraulic piping is one of the core components of a hydraulic system. This is because in the case of devices that use hydraulic pressure as a power source, hydraulic oil is supplied through hydraulic piping to operate. Compared to the main hydraulic assembly, its importance is low, so there are not many studies or failure analysis cases on it. However, contrary to this, cases of hydraulic pipe failure account for a significant proportion of the total number of failures, requiring in-depth technical review. In this study, we aim to analyze the causes of failures in hydraulic pipes of self-propelled guns operated by the military and propose improvement measures. It is expected that this study will aid as a reference for problem solving when similar failures occur in the future.

KCEV(Korean Combat Engineer Vehicle) perform the mission of removing mines and various military obstacles buried in the battlefield and opening passageways. It is characterized by modifying the chassis of the K1 series tank and equipping it with an excavator, track-width mine plough, and magnetic signature duplicator. KCEV has a steering wheel, and steering force is transmitted to the transmission steering lever through the steering linkage and acceleration linkage. KCEV can be steered in up to 3 gears, and it was confirmed that there was a risk of interference with the acceleration linkage as a bending occurred in the steering linkage when steering to the right in 3 gears. In this study, we examined the bending of the acceleration linkage and proposed a method to increase the stiffness of the acceleration linkage tube to improve it. Structural analysis was conducted to confirm the effect of increasing rigidity, and the improvement was confirmed by applying it to an actual vehicle. As a result, it was confirmed that not only the bending displacement of the steering linkage was reduced, but also the stress in the bent area was reduced.

This study was conducted to solve the problem of the existing odor management method taking a long time to analyze samples. Using real-time air quality measurement equipment, 17 designated odor substances were measured three times at a business site causing odor complaints. As a result, three substances, hydrogen sulfide, trimethylamine, and methyl mercaptan, were measured at higher levels than the site boundary emission standards inside the business site. In the case of trimethylamine, it was measured about 500 times higher than Odor Threshold Values, and was estimated to be the substance causing the odor. Through an inspection of the business site, improvements were instructed to be made to the wastewater treatment process, which is the emission facility where trimethylamine is generated. Subsequent measurement results showed that designated odor substances were measured within the emission standards at all locations, and it was determined that efficient management of odorgenerating businesses would be possible if Selected Ion Flow tube-Mass Spectrometry was utilized.

This study evaluates the analytical performance of a newly developed miniaturized disposable U-tube for an automated blood viscometer and compares it to conventional viscometers. Whole blood viscosity (WBV), essential for circulatory function, exhibits non-Newtonian behavior, posing challenges for measurement at low shear rates. The blood viscometer, based on a scanning capillary tube method, used disposable U-tubes to measure viscosities across a shear rate range of 1s⁻¹ to 1,000s⁻¹. Precision evaluation showed stable coefficients of variation (CV) across different viscosity levels. Repeatability assessment indicated consistent CV values, demonstrating the reliability of the device. The agreement with the LV-III Brookfield viscometer and MCR 92 Rheometer was analyzed using Bland-Altman plots, which revealed minor systematic biases and consistent differences across the measurement range. Correlation analysis using Passing-Bablok regression showed high correlation coefficients (R > 0.96) with regression slopes close to 1. The newly developed miniaturized disposable U-tube exhibits excellent precision, reliable repeatability, and high correlation with established methods, enhancing laboratory productivity and offering potential for clinical applications. Further studies with human blood samples are recommended to confirm its clinical applicability.

This study improved the work efficiency by supplementing the shortcomings of the manual process by developing a double tube feeding device, and the following results were obtained by conducting the production capacity, production length, and defect rate tests. Developed a double tube production system to enable the simultaneous production of two tubes, increasing the production volume by about 1.5 times. The product length has been improved from semi-automatic to automated, and the production capacity has been improved from 16 to 25 pieces per hour (based on 15m). Developed a double-tube input straight line automatic adjustment feeder, which resulted in reducing the defect rate to less than 1%.

In this study, Pleurotus ostreatus No.42 was cultured in glucose-peptone-yeast-wheat bran medium using a previously reported novel rotary draft tube bioreactor. Versatile peroxidase (VP), a lignin-degrading enzyme, was isolated from a pellet-type mycelium culture grown in the medium for seven days. The VP was purified by sequentially applying ultra-filtration, DEAESepharose CL-6B column, and Mono Q column. SDS-PAGE analysis revealed the molecular weight of VP to be 36.4 KDa with an isoelectric point of 3.65. The amino acid sequence was confirmed as VTCATGQTT. The purified VP was observed to possess the property of not only oxidizing Mn ions but also decomposing veratryl alcohol, a non-phenolic compound. The catalytic ability of VP is a subject for future research.

Recently, the International Maritime Organization is strengthening regulations for ships operating in polar regions. Hence, insulated multi-core tubes as components for vessels operating in extreme cold need to be investigated in various aspects. Furthermore, the demand for research on electric propulsion vessels is also increasingly growing. Thus, to utilize a 4-core insulated multi-core tube with glass wool as insulation, which was previously developed for ships operating in polar regions, as a water-cooled electrical cable, this study conducted an experiment on the temperature change when water at normal temperature 25℃ was supplied as a coolant under the overcurrent varied from 10A to 25A. As a result, the temperature increase of the core in 10A condition was 3.3℃, but it increased to 13.05℃ in the 25A condition. This showed that a temperature difference of approximately 9.75℃ occurred according to the overcurrent load. However, the coolant inlet and outlet temperatures were relatively uniform around 1℃ in all conditions. This suggests that increasing the residence time by proper control of the coolant flow in the future could achieve a higher cooling effect.

Although the proportion of coal-fired power generation is decreasing, efficient operating technology is needed to continuously invest in facilities and reduce maintenance costs until it is abolished. Boilers, one of the main facilities of power plants, operate for a long time in harsh environments of high temperature and high pressure. In addition, damage due to deterioration is likely to occur depending on the fuel and tube material used. It is very important to judge soundness because damage caused by deterioration adversely affects facility operation. Previously, replication method was used to analyze the progress of deterioration. In the replication method, pre-treatment such as chemical treatment is performed on the boiler tube in the field, the area is reproduced by attaching a film, and the replicated film is determined by an expert in the laboratory with an expensive microscope. However, this method involves substantial costs and time requirements, as well as the possibility of human errors. To address these issues, we developed a mobile health assessment system in this research. Since it is detachable and takes images in real time, this system enables swift evaluations across a broad range and facilitates the assessment of preprocessing quality. In addition, it was intended to reduce existing human mistakes by developing a degradation classification algorithm using the merger cluster method.

Radiant tubes heat exchangers are critical components that facilitate the heat transfer process to steel in an annealing furnace, and it addresses several engineering problems, such as thermal stress and mechanical failure due to long-term thermal cycling, which can significantly affect the longevity of the tubes and maintenance requirements. In this study, we used commercial software (ANSYS) to simulate the thermal stress and deformation of radiant tubes subjected to extreme thermal conditions and pressure loads. We evaluated both thermally induced deformation and creep deformation, which is a time-dependent deformation under constant stress over the long term. The results showed that uneven temperature conditions and pressure loads lead to significant deformation and potential failures. To mitigate these engineering challenges, we also tested several designs that include supporting brackets. This study provides valuable insights for designing radiant tube heat exchangers in annealing furnaces to extend their lifespan and ensure system safety.

Due to its excellent processability, thermal conductivity and high corrosion resistance, copper tubes applied to heat exchangers are being joined through brazing to increase heat exchange efficiency. In order to improve performance, the issue of joint quality of copper tubes, a major member of heat exchangers, is emerging, so research is needed to obtain excellent joint quality of brazing joints that may be damaged. In this study, the quality change of joints according to process variables was studied through induction heating brazing experiments using high frequency. The depth of penetration, which indicates the quality of the junction, was measured, and the center position of the high-frequency electrode and the height of the electrode, which change the location of the heat source applied to the junction, were selected as process variables. Lastly, the thermal image data obtained between the brazing experiments were obtained and the joint quality according to the temperature gradient of the joint was analyzed.

The shell & tube-type heat exchanger has been frequently used because it shows simple structure, easy manufacturing and wide operation conditions among many heat exchangers. This study aims to investigate the characteristics for thermal flow of coolant and the possibility of damage for tube equipped with shell due to thermal stress. For these purposes, The thermal flow of coolant in tube was simulated using ANSYS-CFX program and thus the behaviors of coolant were evaluated with standard k-ε turbulence model. As the results, as the flow rate of coolant in tube was increased, the mean relative pressure was also increased with quadratic curve, however, as the surface temperature of tube was increased, mean temperature difference was linearly increased. Finally it showed that the damage of tube could be predicted, that is, which tube was the most weak due to thermal stress.

지난 10년간 선박의 횡동요 복원력 상실에 의한 해양사고가 지속해서 증가하고 있어, 횡동요 운동을 효과적으로 줄일 수 있는 장치가 필요한 실정이다. 횡동요 감쇄 탱크는 단순한 설치만으로 횡동요 저감을 가져오는 대표적인 수동형 제어장치로 그 장점이 널리 알려져 있다. 따라서 본 연구에서는 U-튜브형 횡동요 감쇄 탱크의 수치해석 기법을 개발하고자 한다. 특히, 해석기법의 검증을 위해 자유 수면 높이를 실험을 통해 계측하였다. 수치해석기법은 메쉬 의존성, 난류모델 ( ,  , Reynolds Stress Model), 시간 간격 크기 및 반복 횟수 등의 영향을 비교하여 개발하였다. 최종적으로 개발된 해석기법은 Realizable  이 난류 모델에 10-2s 수준의 시간 간격 크기와 15 회의 반복횟수를 적용하였다. 2가지의 U-튜브형 감쇄 탱크의 조건에서 계측된 자유수면 높이를 이용하여 개발된 해석기법을 검증하였다. 본 연구의 수치해석은 RANS 기반 상용 해석 Solver인 STAR-CCM+ (ver. 17.02)을 이용하였다.

콘크리트 충전강관은 국부좌굴을 방지하고 내화성이 향상되기 때문에 건설현장에서 많이 적용되며 휨성능을 향상시 키기 위해 강관 내부에 철근을 보강하여 사용한다. 그러나 철근은 부식되며 내구성이 저하되기 때문에 이를 대신할 소재에 대 한 연구가 진행되고 있다. 탄소섬유보강근은 철근에 비해 경량이며 고강도와 내부식성이 우수하다는 이점이 있다. 그러나 임계 온도가 250℃로 철근의 임계온도인 538℃에 비해 현저히 낮기 때문에 내화피복이 필요하다. 따라서 열전달해석을 통해 탄소섬 유보강근을 사용하였을 때 온도분포를 확인하고 P-M상관도를 도출하여 적용 가능여부를 확인하고자 한다. 해석결과 내화성능을 확보하기 위해 콘크리트 피복두께 40mm, 뿜칠내화피복재 30mm를 적용하거나 콘크리트 피복두께 60mm, 뿜칠내화피복재 20mm 를 적용하면 3시간 내화성능을 만족하는 것으로 평가되었다.

In this study, the cooling performance change according to the arrangement of the fin-tube heat exchanger using a single tube and the cooling performance change according to the air flow rate were studied. The arrangement of basic heat exchanger was set to 4 columns and 4 rows, and the performance change was studied while changing the columns and rows. In addition, the performance change was investigated by changing the air flow rate of the basic heat exchanger.

The restraints are used in the intensive care unit as a way to restrict the movement of the whole body or part of the body for the safety of the patient, such as maintaining medical equipment, preventing falls and patient self tube removal through regulating the patient's behavior. However, the physical restraints are used for the physical safety of the patient, but that is cause a variety of physical and psychological complications. Thus, nurses in intensive care units who apply restraint on face an ethical dilemma in the confrontation between the nurse's duty to improve the patient's health and protect the patient's safety and the value of the patient's autonomy and dignity. We have two examples are proposed to identify the ethical dilemma situation faced by nurses, to induce an active attitude towards elimination by establishing exactly restraint - removal criteria. In addition, it is proposed to seek a balance of individual values through active communication between the patient and the medical staff regarding the application of the restraint.

The use of heat exchangers in various applications such as chemical, air conditioning systems, fuel processing, and power industries is increasing. In order to improve the performance of the heat exchanger, the problem of bonding quality of the copper tube, which is a major member, is emerging. However, since the copper tube is in the form of a pipe, it is difficult to identify internal defects with external factors. In this study, a thermal imaging camera was used to develop and verify an algorithm for detecting defects in the brazing part, and in the process, the brazing performance characteristics were analyzed according to the electrode position, and finally, a learning model was developed and performance evaluation was performed. It was confirmed that the method of supplying heat to the base material and melting the filler metal through the heat transfer effect is more effective than supplying heat input to the filler metal in the bonding process of copper tubes through high-frequency induction heating brazing. Thermal image data was used to develop a defect discrimination model, and 80% of training data and 20% of test data were selected, and a neural network-based single-layer copper tube brazing defect discrimination model was developed through k-Flod cross-validation., the prediction accuracy of 95.2% was confirmed as a result of the error matrix analysis.