• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4A
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• pp.407-419
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• 2009

The purpose of this study is to investigate the seismic behavior of precast segmental PSC bridge columns with precast concrete footings and to provide the details and reference data. Six precast segmental PSC bridge columns were tested under a constant axial load and a cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. A bonded or unbonded tendon element based on the finite element method, that can represent the interaction between tendon and concrete of prestressed concrete member, is used. A joint element is modified to predict the inelastic behaviors of segmental joints. This study documents the testing of precast segmental PSC bridge columns with precast concrete footings and presents conclusions based on the experimental and analytical findings.

• Biomedical Science Letters
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• v.29 no.2
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• pp.81-87
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• 2023

Pan-Enterovirus (Pan-EV) infects millions of children and infants worldwide every year. As severe infections have recently been reported, the need for monitoring has consequently intensified. Pan-EV is a categorical name for waterborne enteroviruses belonging to the Picornaviridae family, and includes a wide range of pathogens including Coxsackievirus (CoxV), Echovirus (EcoV) and Enterovirus (EV). In this study, we proposed an optimal RT-nested PCR method for diagnosis of various types of Pan-EV in an aquatic environment and developed a positive control. Considering detection sensitivity, specific reaction, and final identification, one condition capable of amplifying 478 bp among the four candidates in the 1^st round PCR (RT-PCR) and one condition in the 2^nd round PCR (nested PCR) were selected. Through the detection of nucleic acids extracted from 123 groundwater samples and the detection sensitivity test based on artificial spiking in the sample, the methods are optimal for non-disinfected water samples such as groundwater. We developed a positive control for Pan-EV detection that can be amplified to different sizes under the two conditions. Accuracy could be further improved by testing for contamination from the control group. The method proposed in this study and the positive control developed are expected to be used in monitoring Pan-EV in aquatic environments including groundwater through future research using more samples.

• Structural Engineering and Mechanics
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• v.87 no.3
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• pp.221-229
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• 2023

Urbanization and industrialization have significantly increased the amount of solid waste produced in recent decades, posing considerable disposal problems and environmental burdens. The practice of waste utilization in concrete has gained popularity among construction practitioners and researchers for the efficient use of resources and the transition to the circular economy in construction. This study employed Lytag aggregate, an environmentally friendly pulverized fuel ash-based lightweight aggregate, as a substitute for natural coarse aggregate. At the same time, fly ash, an industrial by-product, was used as a partial substitute for cement. Concrete mix M20 was experimented with using fly ash and Lytag lightweight aggregate. The percentages of fly ash that make up the replacements were 5%, 10%, 15%, 20%, and 25%. The Compressive Strength (CS), Split Tensile Strength (STS), and deflection were discovered at these percentages after 56 days of testing. The concrete cube, cylinder, and beam specimens were examined in the explorations, as mentioned earlier. The results indicate that a 10% substitution of cement with fly ash and a replacement of coarse aggregate with Lytag lightweight aggregate produced concrete that performed well in terms of mechanical properties and deflection. The cementitious composites have varying characteristics as the environment changes. Therefore, understanding their mechanical properties are crucial for safety reasons. CS, STS, and deflection are the essential property of concrete. Machine learning (ML) approaches have been necessary to predict the CS of concrete. The Artificial Fish Swarm Optimization (AFSO), Particle Swarm Optimization (PSO), and Harmony Search (HS) algorithms were investigated for the prediction of outcomes. This work deftly explains the tremendous AFSO technique, which achieves the precise ideal values of the weights in the model to crown the mathematical modeling technique. This has been proved by the minimum, maximum, and sample median, and the first and third quartiles were used as the basis for a boxplot through the standardized method of showing the dataset. It graphically displays the quantitative value distribution of a field. The correlation matrix and confidence interval were represented graphically using the corrupt method.

• Journal of radiological science and technology
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• v.46 no.6
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• pp.543-551
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• 2023

In this study, the aim was to assess the shielding performance of different 3D printing materials, specifically those produced using FDM, SLA, and CJP methods, with a focus on their application as shielding devices in clinical settings. Additionally, the weight of lead shielding materials can evoke reluctance in pediatric patients undergoing X-ray imaging. A total of 12 materials were printed using their respective 3D printers. These materials were then subjected to X-ray testing using diagnostic X-ray equipment and an exposure meter. The goal was to evaluate their shielding capabilities in comparison to 1 mm lead. The results of this evaluation revealed that VisiJet PXL-Pastel, produced using the CJP method, exhibited the highest shielding performance. Therefore, VisiJet PXL-Pastel by CJP method was selected for the creation of a shielding device designed for pediatric reproductive organs. Subsequent tests demonstrated that both the newly created shielding device and conventional lead shielding equipment achieved the same maximum shielding rate at 50 kVp. Specifically, the shielding rate for the 3D printed device was measured at 84.53%, while the conventional lead shielding equipment, categorized as Apron1 (85.74%), Apron2 (99.98%), and Apron3 (99.04%), demonstrated similar performance. In conclusion, the CJP-produced VisiJet PXL-Pastel material showcased excellent radiation shielding capabilities, allowing for anatomical observations of the target organs and their surrounding structures in X-ray images. Furthermore, its lower weight in comparison to traditional lead shielding materials makes it a clinically practical and useful choice, particularly for pediatric applications.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.3
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• pp.129-139
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• 2024

In this study, the SBC system, a new mechanical joint method, was developed to improve the constructability of precast concrete (PC) beam-column connections. The reliability of the finite element analysis model was verified through the comparison of experimental results and FEM analysis results. Recently, the intermediate moment frame, a seismic force resistance system, has served as a ramen structure that resists seismic force through beams and columns and has few load-bearing walls, so it is increasingly being applied to PC warehouses and PC factories with high loads and long spans. However, looking at the existing PC beam-column anchorage details, the wire, strand, and lower main bar are overlapped with the anchorage rebar at the end, so they do not satisfy the joint and anchorage requirements for reinforcing bars (KDS 41 17 00 9.3). Therefore, a mechanical joint method (SBC) was developed to meet the relevant standards and improve constructability. Tensile and bending experiments were conducted to examine structural performance, and a finite element analysis model was created. The load-displacement curve and failure pattern confirmed that both the experimental and analysis results were similar, and it was verified that a reliable finite element analysis model was built. In addition, bending tests showed that the larger the thickness of the bolt joint surface of the SBC, the better its structural performance. It was also determined that the system could improve energy dissipation ability and ductility through buckling and yielding occurring in the SBC.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.882-888
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• 2005

Procedure for analysis of methylmercury in fish was developed, involving addition of HCl, extraction with toluene, and clean-up using L-cystein solution. Obtained extract is analyzed by gas chromatography with electron capture detector using Ulbon HR-Thermon-Hg column. Detection limit and recovery of the method were 0.005mg/kg (expressed as Hg), 98-107 (103%), respectively. Total mercury and methylmercury concentrations in 175 commercial fish samples ranged from [mean-max (mean), unit: mg/kg]: 0.014-1.200 (0.270) and 0.006-0.901 (0.168) in tuna-fish, 0.020-0.934 (0.323) and 0.012-0.553 (0.149) in martin-fish, 0.082-0.782 (0.391) and 0.040-0.436(0.201) in shark, 0,023-0.031 (0.026) and 0,013-0.018 (0.015) in salmon, 0.098-0.193 (0.133) and 0.031-0.015(0.090) in tilefish, and 0,031-0.214 (0.089) and 0.016-0.093 (0.042) in canned tuna respectively. No sample of analyzed fish exceeded 1.0mg/kg wet wt., limit for methylmercury established by Codex. In all species examined, estimated weekly intake was lower than Provisional Tolerable Weekly Intake recommended by the JECFA (the Joint FAO/WHO Expert Committee on Food Additives).

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.129-144
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• 2019

This study aimed at developing an accelerated collection method that reduces measurement and collection time by improving and complementing the desiccator method, which is mainly used for quality control in wood-based panels and furniture production sites. First, this study measured the formaldehyde emissions from the wood-based panels by grade using the desiccator method. Further, this study compared the desiccator method with the developed process and analyzed the correlation in optimal temperature, time, and exposed area. The results showed that the developed process resulted in relatively similar outcomes in comparison to the desiccator method when the temperature was $100^{\circ}C$, the time was 1 h, and two specimens were used, at which the correlation was high. To verify the developed process, this study commissioned Korea Conformity Laboratories with the standardized temperature, time, and the number of specimens to compare them with the specimen that was not used in the actual test. As a result, the correlation to the desiccator method was shown to be very high. However, the formaldehyde emission measured by the accelerated collection process was mostly higher than that measured by the desiccator method. The formaldehyde emission grades from several specimens were one level higher. However, from the perspectives of quality control, it was determined that the accelerated collection method developed in this study could be sufficiently used.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.29-42
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• 1999

The SASW (Spectral-Analysis-of-Surface-Waves) method, which evaluates the stiffness structure of the subsurface and structures nonintrusively and nondestructively, has been successfully used in the civil engineering applications. However, the SASW method assumes that the subsurface or structures consist of horizontal multi-layers, so that the method has some difficulty in continuously evaluating the integrity of a tunnel lining and a pavement system. This difficulty prevents the SASW method from being used to generate a tomographic image of stiffness for the subsurface or structures. Recently, the GPR technique which has the advantage of continuously evaluating integrity of the subsurface and structures has been popular. This advantage of GPR technique initiated the efforts to make the SASW method, which is superior to GPR and other nondestructive testing methods due to its capability of evaluating stiffness and modulus, be able to do continuous evaluation of stiffness structure, and the efforts finally lead to the development of \ulcornerTomographic SASW Technique.\ulcorner Tomographic SASW technique is a variation of the SASW method, and can generate a tomographic image of stiffness structure along the measurement line. The tomographic SASW technique was applied to the investigation of lateral variability of a sand box placed by the raining method for the purpose of verifying its effectiveness. Tomographic SASW measurements on the sand box revealed that the investigated sand box has different shear stiffness along the measurement line, which gave a clue of how to make a better raining device.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.983-989
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• 2021

In this study, we intend to evaluate image quality and provide to clinical basic data by applying to 2D TSE (RT) and 3D GRASE (BH) techniques using Fast MRCP testing methods for application to patients in poor patient condition. Data were analyzed for 30 patients (15 males, 15 females, and 64±4.26 average age) who underwent MRCP tests. The equipment used was Ingenia CX 3.0 T equipment and Ds anterior coil was used for data acquisition. SNR and CNR of each image were measured through quantitative analysis, and the quality of the image was evaluated by dividing it into 5 grades for qualitative evaluation. The image evaluation was performed on the paired t-test and the Wilcoxon test, and when the p value was 0.05 or less, it was considered to be significant. As a result of quantitative analysis of SNR and CNR, 3D GRASE (BH) was measured high when comparing the two techniques, 2D TSE (RT) MRCP and 3D GRASE (BH) (p<0.05). The qualitative analysis result is a sharpness of the bile duct: 3D GRASE(BH): 4.12±0.03, Overall image quality: 3D GRASE(BH): 4.21±0.91 was high (p=0.001). The motion artifact of the bile duct showed no significant difference with two techniques(2D TSE(RT): 4.41±0.04, 3D GRASE(BH): 4.53±0.14(p=0.067). However, the background suppression obtained significant results with 2D TSE(RT) of 4.14±0.55(p=0.001). In conclusion, as a result of using the Fast MRCP testing method, MRCP images obtained by 3D GRASE (BH) had an advantage over MRCP images using 2D TSE (RT). However, there will be useful results of 2D TSE(RT) MRCP technique in patients who have difficulty holding their breath.

• YAKHAK HOEJI
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• v.56 no.5
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• pp.288-292
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• 2012

The aim of the paper is to ameliorate old research methods of Korean Pharmaceutical Codex to adjust the newest scientistic level which is necessary to maintain quality of medical supplies effectively. After reviewing result of Establishment of Dissolution Specifications for Generic Drugs in Korea Pharmaceutical Codex Monograph, there are two items chosen for the methods - Establishment of Dissolution Specifications for Generic Drugs in Korea Pharmaceutical Codex Monograph which KFDA researched in 2010, arranged new measuring standard by having an experiment to set measuring method after obtaining each item. According to the result, The experiment includes a measuring method of two items; Nafronyl Oxalate Capsules, and Ticlopidine Hydrochloride Tablets. The research is ameliorated by research methods through several experiments such as High Performance Liquid Chromatography validation, preparing items, implement of trial-experiment and authentic experiment, and experiment on measuring method of regulations of Korea Pharmaceutical Codex. The experiments are taken opinions of experts in KFDA into consideration and wrote out a report of the new measuring method on each last item. The report is combined as each two experiment sections of analyzing method to maintain the quality on the basis of the research in 2010 on setting of dissolution specifications for oral solid dosage forms. The result of measuring method of medical supplies through modernizing trial method of oral solid dosage forms is available to be accurate. In conclusion, this study could contribute to promotion of public health by organizing a basis for safe and high quality of medical supplies in domestic market.