• Nuclear Engineering and Technology
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• v.50 no.1
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• pp.190-202
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• 2018

Maintaining the integrity of the major equipment in nuclear power plants is critical to the safety of the structures. In particular, the soundness of the piping is a critical matter that is directly linked to the safety of nuclear power plants. Currently, the limit state of the piping design standard is plastic collapse, and the actual pipe failure is leakage due to a penetration crack. Actual pipe failure, however, cannot be applied to the analysis of seismic fragility because it is difficult to quantify. This paper proposes methods of measuring the failure strain and deformation angle, which are necessary for evaluating the quantitative failure criteria of the steel pipe elbow using an image measurement system. Furthermore, the failure strain and deformation angle, which cannot be measured using the conventional sensors, were efficiently measured using the proposed methods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.1
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• pp.93-98
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• 2000

We performed this study to determine the radioprotective effects of Shi-Quan-Dai-Bu-Tang, as a prescription of traditional Oriental medicine, and its major ingredients. The jejunal crypt survival, endogenous spleen colony formation, and apoptosis in jejunal crypt cells were investigated in mice irradiated with high and low dose of ${\gamma}$-rays. The administration of danggui, baishaoyao, rensan, gancao or baifuling before irradiation protected the jejunal crypts (p<0.005). Shoudehuang, danggui, baishaoyao, rensan and huangqui increased the formation of endogenous spleen colony (p<0.05). Chuanxiong, baishaoyao, rensan and baifuling reduced the frequency of radiation-induced apotosis (p<0.05). The results indicated that the extracts of danggui, baishaoyao, rensan and baifuling may have radoprotective effects in mice irradiated with high and low dose of ${\gamma}$-rays. The radioprotective effect of the prescription, Shi-Qaun-Da-Bu-Tang, was not significant.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.245-253
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• 2017

The relative displacement of a piping system installed between isolated and nonisolated structures in a severe earthquake might be larger when without a seismic isolation system. As a result of the relative displacement, the seismic risks of some components in the building could increase. The possibility of an increase in seismic risks is especially high in the crossover piping system in the buildings. Previous studies found that an elbow which could be ruptured by low-cycle ratcheting fatigue is one of the weakest elements. Fatigue curves for elbows were suggested based on component tests. However, it is hard to find a quantitative evaluation of the ultimate state of piping elbows. Generally, the energy dissipation of a solid structure can be calculated from the relation between displacement and force. Therefore, in this study, the ultimate state of the pipe elbow, normally considered as failure of the pipe elbow, is defined as leakage under in-plane cyclic loading tests, and a failure estimation method is proposed using a damage index based on energy dissipation.

• Journal for History of Mathematics
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• v.18 no.4
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• pp.1-16
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• 2005

Chosun dynasty mathematician Park Yul (1621 - ?) wrote San Hak Won Bon(算學原本) which was posthumously published in 1700 by his son Park Du Se (朴斗世). It is the first mathematics book whose publishing date is known, although we have Muk Sa Jib San Bub (默思集算法) by Gyung Sun Jing (慶善徵, 1616-?). San Hak Won Bon is the first Chosun book which deals with tian yuan shu (天元術) and was quoted by many Chosun authors. We do find it in the library in Korea University. In this paper, we investigate its contents together with its historical significance and influences to the development of Chosun dynasty Mathematics and conclude that Park Yul is one of the most prominent Chosun dynasty mathematicians.

• Journal of Microbiology
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• v.39 no.4
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• pp.286-292
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• 2001

During mitosis. the proper segregation of duplicated chromosomes is corrdinated by a spindle check-point. The bifurcated spindle checkpoint blocks cell cycle progression at metaphase by monitoring unattached kinetochores and inhibits mitotic exit in response to the misorientation of the mitotic spin- dle Ibd1p/Bfa1p is a spindle checkpoint regulator of budding yeast in the Bub2p checkpoint pathway for mitotic exit and its disruption abolishes mitotic arrest when proper organization of the mitotic spin-dls inhibited. Ibd1p/Bfa1p localizes to the spindle pole body, a microtublue-organizing center in yeast, and its overexpression arrests the cell cycle in 80% of cells with an enlarged budy at mitosis and in 20 % of cells with multiple buds. In this study, we found that the C-terminus of Ibd1p/Bfa1p phys-ically interacts with Skp1p, a key component of SCF (Skp1/cullin/F-box) complex for ubiquition-medi-ated proteolysis of cel cycle regulatores as well as an evolutionally conserved kinetochore protein for cell cycle progression. A putative F-box motif was found in the C-terminus of Ibd1p/Bfa1p and its function was investigated by making mutants of conserved residues in the motif. These Ibd1p/Bfa1p mutants of a putative F-box interacted with SKp1p in vitro by two-hybrid assays as wild type Ibd1p/Bfa1p. Also these Ibd1p/Bfa1p utants displayed the overexpression phenotypes of wild type Ibd1p, when over-expressed under inducible promoters . These results suggest that a putative F-box motif of Ibd1p/Bfa1p is not essential for the interaction with SKp1p and its function in mitotic exit and cytokinesis.

• Nuclear Engineering and Technology
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• v.18 no.3
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• pp.175-182
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• 1986

The KNUI (Korea Nuclear Unit 1) loss of offsite power transient as a design-base accident has been simulated using the RELAP5/MOD1/NSC computer code. The analysis is carried out using the best-estimate methodology, but the sequence and its assumptions are based on the evaluation methodology th at emphasizes conservatism. Important thermal-hydraulic parameters such as average temperature, steam generator level and pressurizer water volume are compared with the results in the KNU1 Final Safety Analysis Report (FSAR). The present analysis gives much lower RCS average temperature and pressurizer water volume, and much higher S/G water volume at the turnaround point, which may be considered to be additional improved safety margins. This is expected since the present analysis deals with the best-estimate thermal-hydraulic models as well as the initial conditions on a best-estimate basis. These additional safety margins may contribute to further validate the safety of the KNU1 in this type of accidents(Decrease in Heat Removal by the Secondary System).

• Nuclear Engineering and Technology
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• v.18 no.1
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• pp.9-16
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• 1986

Simulation of the system thermal-hydraulic parameters was carried out following the KNUl (Korea Nuclear Unit-1) loss of normal feedwater transient sequence occurred on November 14, 1984. Results were compared with the plant transient data, and good agreements were obtained. Some deviations were found in the parameters such as the steam flowrate and the RCS (Reactor Coolant System) average temperature, around the time of reactor trip. It can be expected since the thermal-hydraulic parameters encounter rapid transitions due to the large reduction of the reactor thermal power in a short period of time and, thereby, the plant data involve transient uncertainties. The analysis was performed using the RELAP5/MOD1/NSC developed through some modifications of the interphase drag and the wall heat transfer modeling routines of the RELAP5/MOD1/CY018.

• Nuclear Engineering and Technology
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• v.22 no.1
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• pp.12-19
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• 1990

The Loss of Offsite Power Transient at 77.5% power which occurred on June 9, 1981 at the Kori Unit 1 PWR (Pressurized Water Reactor) is simulated using the RELAP5/MOD2 system thermal-hydraulics computer code. Major thermal-hydraulic parameters are compared with the available plant data. The comparison of the analysis results with the plant data demonstrates that the RELAP5/MOD2 code has the capability to simulate the thermal-hydraulic behaviour of PWRs under accident conditions of this type with accuracy, except the pressurizer pressure and level. The pressurizer pressure increase is sensitive to the in surge now it is believed that the interracial heat transfer in a horizontal stratified flow regime may be estimated low and the compression effect due to insurge flow may be high. In the nodalization sensitivity study it is found that S/G noding with junctions between bypass plenum and steam dome is preferred to simulate the S/G water level decreasing and avoid the spurious level peak at trubine trip.

• Journal of Chest Surgery
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• v.51 no.1
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• pp.35-40
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• 2018

Background: The treatment of malignant pleural mesothelioma (MPM) is challenging, and multimodal treatment including surgery is recommended; however, the role of surgery is debated. The treatment outcomes of MPM in Korea have not been reported. We analyzed the outcomes of MPM in the context of multimodal treatment, including surgery. Methods: The records of 29 patients with pathologically proven MPM from April 1998 to July 2015 were retrospectively reviewed. The treatment outcomes of the surgery and non-surgery groups were compared. Results: The overall median survival time was 10.6 months, and the overall 3-year survival rate was 25%. No postoperative 30-day or in-hospital mortality occurred in the surgery group. Postoperative complications included tachyarrhythmia (n=4), pulmonary thromboembolism (n=1), pneumonia (n=1), chylothorax (n=1), and wound complications (n=3). The treatment outcomes between the surgery and non-surgery groups were not significantly different (3-year survival rate: 31.3% vs. 16.7%, respectively; p=0.47). In a subgroup analysis, there was no significant difference in the treatment outcomes between the extrapleural pneumonectomy group and the non-surgery group (3-year survival rate: 45.5% vs. 16.7%, respectively; p=0.23). Conclusion: Multimodal treatment incorporating surgery did not show better outcomes than non-surgical treatment. A nationwide multicenter data registry and prospective randomized controlled studies are necessary to optimize the treatment of MPM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.24-33
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• 2002

The cell search scheme for W-CDMA consists of the following three stages: slot synchronization(1st stage), group identification and frame boundary detection(2nd stage), and long code identification(3rd stage). The performance of the cell search when a mobile station is switched on, which is referred to as initial cell search, is decreased by the initial frequency and timing error. In this paper, we propose the pipeline structured initial cell search scheme using time trackers to compensate for the impact of the initial timing error in the stage 2 and stage 3. The simulation results show that the performance of the proposed scheme is maximal 1.5dB better than that of the conventional one when the initial timing error is near ${\pm}T_c$/2.