• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.643-648
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• 1996

Recent failures of Heat Transport (HT) system Liquid Relief Valves (LRVs) at several CANDU 6 plants resulted in heavy water spills. A multi-discipline KAERI task team along with AECL representatives was set up to assess the specific implications on the Wolsong 2/3/4 station. The study applied the knowledge gained from the generic study by conducting a fundamental review of the specific design of Welsong 2/3/4. The purpose of the study was to demonstrate compliance with the relevant codes and licensing regulations and to identify the improvements to the design and operating procedures applicable to Wolsong 2/3/4. This paper presents the key recommendations of this study.

• The Korean Journal of Malacology
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• v.27 no.2
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• pp.131-141
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• 2011

Boring caracteristics, boring rate, and predation, rates on the valves of the seed and adult clams of Meretrix petechialis by Glossaulax didyma didyma in the shellfish aquafarm and the indoor rearing aquarium were investigated by various morphometric data. The investigations were carried out from June to September, 2007. The morphology of drilled holes on the valves of M. petechialis showed the crater type as seen in the spats of Ruditapes philippinarum and M. lusoria. The sizes of the outer diameters of holes were greater than the inner diameters of the holes on the valves of M. petechialis in the shellfish aquafarm and the indoor aquarium at the laboratory. On the whole, the sizes of the holes on the valves of the seeds of M. petechialis was smaller than those bored holes on the adult valves. The location of the bored holes on the valves of the seeds varied widely with the the sizes of the individuals of M. petichialis, while most of holes on the valves of adult clams were located near the umbo position of the valves of the clams in the shellfish aquafarm and the indoor aquarium at the laboratory. On the whole, the outer and inner diameters of the bored holes increased with increase of shell lengths of the clams in the shellfish aquafarm and the indoor rearing aquarium at the laboratory. The authors could confirm experimentally the boring snail, G. didyma didyma, drilled the seeds and adult clams of M. petechialis. In the experiments for 15 days (three times repeated) in the indoor rearing aquarium at the laboratory, the mortality of dead shells to total shells of M. petechialis by boring snail Glossaulax didyma didyma was totally average 41.5%, and percent of drilled shells to total dead shells of clams by the boring snail was average 47.1%. Of total shells, percent of drilled shells to total shells of clams by the boring snail was totally average 19.3%. Predation of G. didyma didyma were greater at night than the day time. Average 0.5 seed and adult individuals of M. petewchialis were consumed per G. didyma didyma, per day. Predation varied with shell lengths of M. petechialis and shell widths of G. didyma didyma.

• Journal of Chest Surgery
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• v.29 no.10
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• pp.1111-1117
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• 1996

Structural deterioration of the bioprosthetic xenograft valves due to primary tissue failure occurs in two modes: from fatigue lesions with tear and wear with or without calcification and from calcification with obstruction. Two groups of consecutive 56 patients with the Hancock porcine ortic valve(HM) and of 1 13 patients with the standard-profile onescu-Shiley bovine pericardial valve(ISM) explanted from mitral position at the time of re-replacement surgery for primary tissue failure at Seoul national University Hospital until 1994, were studied for clinical and pathological features. Their ages at primary implant were 31.9 $\pm$9.2 years In HM and 30.4$\pm$ 12.5 years in ISM. Hemodrnamic dysfunction of the failed mitral bloprostheses were predominantly insufficiency in HM(64.3%) and stenosis in ISM(51.3%)(p<0.001). Pathologic findings of the explanted mitral valves reflected these hemodynamic changes, revealing failure more often from tissue damage(tears and wears) in HM and more often from calcification in ISM(p< 0.001). Explant period(from primary implant to explant) was relatively short in ISM(8.7$\pm$2.6years), compared with the one in HM(10.4 $\pm$2.6 years)(p<0.001). In conclusion, both the Hancock and the lonescu-shiley valves would fail from calcification as well as issue damage. However, while the Hancock porcine valves in mitral position failed more frequently from tissue failure and insufficiency, the standard-profile lonescu-Shiley pericardial valves did from calcification and stenosis, especially in young pAtients . Although the possibility of less occurrence of valve failure from mechanical reasons may be expected with newer generation bloprostheses, it does not seem to Improve durability significantly unless further refinement in antimineralization is achieved. Therefore, clinical use of the glutaraldehyde-treated bioprosthetic valves is, at present, limited to the patients of advanced age groups.

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.99-104
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• 2001

In this study, selecting methods of the hydraulic valve and evaluation item for development of reliability testing standard are c]early defined. And, we developed reliability testing standard of the hydraulic valves which are as follows, - Hydraulic directional control valve, - Hydraulic on-off solenoid valve - Hydraulic PWM valve, - Hydraulic check valve, - Hydraulic relief valve, - Hydraulic reducing valve, - Hydraulic flow control valve

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.105-111
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• 2001

In this study, for improvement of pneumatic valve reliability, we grasped the falling-off problem in efficiency of domestic valve and performed detailed analysis the relating International standards, and we also decided sampling method and reliability evaluation items to be evaluated valves. And, in addition, we describe the developed evaluation standard to increase the competition power and to improve the reliability of domestic pneumatic valve manufacturers through deciding of test conditions and thesis of evaluation procedures to each evaluation items.

• Journal of the Korean Society of Safety
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• v.13 no.2
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• pp.104-108
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• 1998

In order to evaluate the performances of safety valves for low pressure, the popping pressure and flow rate of the natural gas have been investigated. The measured results of the popping pressure show that there is a big scattering depending on the manufacture year of a safety valve. And sample A showed the ideal popping pressure mode compared to other B and C samples. The popping flow rate of the safety valve is proportional to the seat size as the inlet pressure increases. These results may be used as a guideline for a design and diagnosis of the safety valve.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.360-364
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• 1994

This paper is concerned with extracting the diagnostic signature for motor-operated valves (MOV's) noninvasively. A torque estimator is developed and tested to obtain electical torque of the induction motors which are attached to the MOV's. Inverse filter is used to recover the gear meshing forces from the measured actuator housing vibration, which contain the gear rotation information. Frequency demodulation techniques are performed and an adaptive linear bandpass filter is implemented to improve signal-to-noise ratio. Finally, stand-alone valve experiments are carried out to validate the signature extraction scheme.

• Journal of Chest Surgery
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• v.11 no.4
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• pp.535-540
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• 1978

Between January 1974 and November 1978, 23 cases of double valve replacement were done in the Department of Thoracic Surgery, Seoul National university Hospital. All had symptoms of rheumatic valvular heart disease and belonged to functional class III or IV according to NYHA classification. Among 23 cases, mitral and aortic valves were replaced in 14, and mitral and tricuspid valves in 9 cases. Six operative deaths [26%] and 4 late deaths [23%] were found. In the former group 5 and in latter one operative death were noted. Main cause of operative death was low cardiac output syndrome due to myocardial failure. Among 4 late deaths, 2 were caused by thromboembolism, one by bacterial endocarditis, and one by arrhythmia.

• Journal of Magnetics
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• v.13 no.3
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• pp.81-84
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• 2008

Spin injection and detection in lateral spin valves with double nonmagnetic bottom electrodes are investigated theoretically. Spin-polarized current injected from a magnetic electrode is split to two bottom electrodes, and nonlocal spin signals between the other magnetic electrode and the nonmagnetic electrodes are calculated from drift-diffusion equations. It is shown that the spin signal is approximately proportional to the associated current in the electrode.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.283-288
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• 2001

This study provides analytical evaluation of the Dual-Ann Work Module. The current hydraulic system was modeled using the HyPneu and analyzed to find the cause of the instability. The cause of the instability was determined to be primarily an interacting involving the pilot operated check valves and the counterbalance valves for fail safe mode of operation. A new design concept was developed to eliminate the potential for unstable operation while adequately meeting the need for a fail-safe feature.