• Journal of the Korean Society of Safety
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• v.26 no.6
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• pp.13-19
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• 2011

The purpose of this study is to examine the cause of damage to electrolytic capacitors and to present the heat generation mechanism in order to prevent the occurrence of similar problems. From the analysis results of electrolytic capacitors collected from accident sites, the fire causing area can be limited to the primary power supply for the initial accident. From the tests performed by applying overvoltage, surge, etc., it is thought that the fuse, varistor, etc., are not directly related to the accidents that occurred. The analysis of the characteristics using a switching regulator showed that the charge and discharge characteristics fell short of standard values. In addition, it is thought that heated electrolytic capacitors caused thermal stress to nearby resistances, elements, etc. It can be seen that the heat generation is governed by the over-ripple current, application of AC overvoltage, surge input, internal temperature increase, defective airtightness, etc. Therefore, when designing an electrolytic capacitor, it is necessary to comprehensively consider the correct polarity arrangement, appropriate voltage application, correct connection of equivalent series resistance(ESR) and equivalent series inductance(SEL), rapid charge and discharge control, sufficient margin of dielectric tangent, etc.

• Journal of the Korean Society of Safety
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• v.38 no.6
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• pp.9-15
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• 2023

Hydrogen is gaining attention as a sustainable and renewable energy source, potentially replacing fossil fuels. Its high diffusivity, wide flammable range, and low ignition energy make it prone to ignition even with minimal friction, potentially leading to fire and explosion risks. Workplaces manage ignition risks by classifying areas with explosive atmospheres. However, the effective installation of a blast wall can significantly limit the spread of hydrogen, thereby enhancing workplace safety. To optimize the wall installation of this barrier, we employed the response surface methodology (RSM), considering variables such as wall distance, height, and width. We performed 17 simulations using the Box-Behnken design, conducted using FLACS software. This process yielded two objective functions: explosion likelihood near the barrier and explosion overpressure affecting the blast wall. We successfully achieved the optimal solution using multi-objective optimization for these two functions. We validated the optimal solution through verification simulations to ensure reliability, maintaining a margin of error of 5%. We anticipated that this method would efficiently determine the most effective installation of a blast wall while enhancing workplace safety.

• Nuclear Engineering and Technology
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• v.39 no.2
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• pp.103-110
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• 2007

The High Temperature Gas-cooled Reactor (HTGR) possesses inherent safety features and is recognized as a representative advanced nuclear system for the future. Based on the success of the HTR-10, the long-time operation test and safety demonstration tests were carried out. The long-time operation test verifies that the operation procedure and control method are appropriate for the HTR-10 and the safety demonstration test shows that the HTR-10 possesses inherent safety features with a great margin. Meanwhile, two new projects have been recently launched to further develop HTGR technology. One is a prototype modular plant, denoted as HTR-PM, to demonstrate the commercial capability of the HTGR power plant. The HTR-PM is designed as $2{\times}250$ MWt, pebble bed core with a steam turbine generator that serves as an energy conversion system. The other is a gas turbine generator system coupled with the HTR-10, denoted as HTR-10GT, built to demonstrate the feasibility of the HTGR gas turbine technology. The gas turbine generator system is designed in a single shaft configuration supported by active magnetic bearings (AMB). The HTR-10GT project is now in the stage of engineering design and component fabrication. R&D on the helium turbocompressor, a key component, and the key technology of AMB are in progress.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1110-1119
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• 2020

The Floating Absorber for Safety at Transient (FAST) is a safety device used in the innovative Sodium-cooled Fast Reactor (iSFR). The FAST insert negative reactivity under transient or accident conditions. However, behavior of the FAST is still unclear under transient conditions. Therefore, the existing Floating Absorber for Safety at Transient Analysis Code (FASTAC) is improved to analyze the FAST movement by considering the reactivity and temperature distribution within the reactor core. The current FAST system is simulated under a single control rod withdrawal accident condition. In this investigation, the reactor thermal power does not return to its initial thermal power even if the FAST inserts negative reactivity. Only a 9 K of coolant temperature margin, in the hottest fuel assembly at EOL, can lead to unnecessary insertion of the negative reactivity. On the other hand, the FASTs cannot contribute to controlling the reactivity when normalized radial power is less than 0.889 at BOL and 0.972 at EOL. These simulation results suggest that the current FAST design needs to be optimized depending on its installed location. Meanwhile, the FAST system keeps the fuel, cladding and coolant temperatures below their limit temperatures with given conditions.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.1
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• pp.41-47
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• 1999

The route of bony invasion and spread pattern of tumor in the mandible are important in management of gingival cancer. Ten patients with gingival cancer involving mandibular body region were operated by composite resection. The radiographic and histopathologic features of the mandibular invasion and spread were analysed and compared. Our results showed that histopathologic extent of tumor invasion were greater than the radiographic prediction, especially in width of the tumor. And the pattern of bony invasion in the body area was mostly found in transmedullary spread rather than perineural spread. The vertical involvement in the mandibular body with tumor was evaluated. It indicated that if a oncologic surgeon was to ensure an adequate safety margin for extirpation of tumor, in most cases, the maintenance of the mandibular continuity is difficult. If the mandibular involvement by gingival cancer was identified radiographically and clinically, segmental mandibulectomy was required for the adequate safety margin, in consideration of the spread pattern in the body area.

• Journal of Gastric Cancer
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• v.12 no.3
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• pp.187-193
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• 2012

Purpose: The aim of this study is to evaluate the feasibility and safety of cardia preserving proximal gastrectomy, in early gastric cancer of the upper third. Materials and Methods: A total of 10 patients were diagnosed with early gastric cancer of the upper third through endoscopic biopsy. The operation time, length of resection free margin, number of resected lymph nodes and postoperative complications, gastrointestinal symptoms, nutritional status, anastomotic stricture, and recurrence were examined. Results: There were 5 males and 5 females. The mean age was $56.5{\pm}0.5$ years. The mean operation time was $188.5{\pm}0.5$ minutes (laparoscopic operation was 270 minutes). Nine patients were T1 stage (T2 : 1), and N stage was all N0. The mean number of resected lymph nodes was $25.2{\pm}0.5$. The length of proximal resection free margin was $3.1{\pm}0.1$ cm and distal was $3.7{\pm}0.1$ cm. Early complications were surgical site infection (1), bleeding (1), and gastro-esophageal reflux disease (1) (this symptom was improved with medication). Late complications were dyspepsia (3) (this symptom was improved without any treatment), and others were nonspecific results of endoscopy or symptom. Conclusions: Cardia preserving proximal gastrectomy was feasible for early gastric cancer of the upper third. Further evaluation and prospective research will be required.

• Toxicological Research
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• v.21 no.4
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• pp.297-301
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• 2005

Farmers are generally expressed to pesticides through mixing loding, application activity and harvesting of crop after application of pesticides. The present work investigated the exposure and risk of furathiocarb to workers when harvesting of cucumber was carried out in green house after application of furathiocarb EC. Glove was used for the hand exposure assessment, socks for foot and dermal patches for the other parts of body. Personal air monitor equipped with a XAD-2 resin was used for the respiratory exposure assessment. During the harvest of cucumber in green house, the initial rate of potential dermal exposure (Day 1) for methidathion was 1.3 mg/hr. The major exposure parts were hand $(78\~83\%),\;thigh\;(5\~7\%)$ and arms $(6\~9\%)$ during 3 days' harvest. No exposure was detected from the respiratory monitoring. For risk assessment, the potential dermal exposure (PDE), the absorbable quantity of exposure (AQE) and the margin of safety (MOS) and margin of exposure (MOE) were calculated. In risk assessment of harvester exposure for 7days, all MOS was > 1 and MOE was > 100 indicating that possibility of risk was little.

• Archives of Craniofacial Surgery
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• v.24 no.5
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• pp.236-239
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• 2023

Porocarcinoma (PC) and basal cell carcinoma (BCC) are distinct skin cancers. Few studies have documented the occurrence of two concurrent types of skin cancers, and to the best of our knowledge, this represents the inaugural report of such a coexisting lesion arising from a capillary malformation. Herein, we report a case of concurrent PC and BCC presenting with capillary malformation. A 93-year-old woman visited our hospital with a protruding mass in her right nasal ala that appeared as a capillary malformation. A biopsy was performed on the skin lesion, and BCC was diagnosed. A wide excision was performed. Permanent biopsy revealed that the skin lesion was a PC with basal cells and squamous differentiation. The safety margin of the deep tissue margin was < 0.1 cm; however, considering the advanced age of the patient, further excision was deemed to not possess any benefits. This case illustrates the importance of recognizing the possibility of multiple skin cancers, even in patients with benign lesions such as capillary malformations. The rarity of this presentation highlights the importance of thorough investigation and histopathological examination of skin lesions in guiding appropriate surgical excision.

• Archives of Plastic Surgery
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• v.50 no.5
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• pp.446-451
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• 2023

Background Elderly patients often have complications of blepharoptosis surgery that can result in the appearance or exacerbation of superficial punctate keratopathy (SPK). However, postoperative changes to SPK status have not been previously reported. We used subjective assessment of symptoms and measurement of SPK scale classification to investigate the safety and efficacy of blepharoptosis surgery in elderly patients. Methods Included in this prospective study were 22 patients (44 eyes) with bilateral blepharoptosis that underwent surgery. Patients comprised 8 males and 14 females with a mean (±standard deviation) age of 75.7 ± 8.2 years (range: 61-89). Blepharoptosis surgery consisted of transcutaneous levator advancement and blepharoplasty including resection of soft tissue (skin, subcutaneous tissue, and the orbicularis oculi muscle). Margin reflex distance-1 (MRD-1) measurement, a questionnaire survey of symptoms and SPK scale classification, was administered preoperatively and 3 months postoperatively for evaluation. Results The median MRD-1 was 1 mm preoperatively and 2.5 mm postoperatively, representing a significant postoperative improvement. SPK area and density scores were found to increase when the MRD-1 increase was more than 2.5 mm with surgery. All 10 items on the questionnaire tended have increased scores after surgery, and significant differences were observed in 7 items (poor visibility, ocular fatigue, heavy eyelid, foreign body sensation, difficulty in focusing, headaches, and stiff shoulders). Conclusion Blepharoptosis surgery was found to be a safe and effective way to maintain the increase in MRD-1 within 2.0 mm. Despite the benefits, surgeons must nonetheless be aware that blepharoptosis surgery is a delicate procedure in elderly people.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.1
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• pp.27-35
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• 2023

Pressure tubes are the main components of PHWR core and serve as the pressure boundary of the primary heat transport system. However, because pressure tubes have changed their geometrical dimensions under the severe operating conditions of high temperature, high pressure and neutron irradiation according to the increase of operation time, all dimensional changes should be predicted to ensure that dimensions remain within the allowable design ranges during the operation. Among the deformations, the diameter expansion due to creep leads to the increase of bypass flow which may not contribute to the fuel cooling, the decrease of critical channel power and finally the deration of the power to maintain the operational safety margin. This study is focused on the modeling of the expansion of the pressure tube diameter based on the operating conditions and measured diameter data. The pressure tube diameter expansion was modeled using the neutron flux and temperature distributions of each fuel channel and each fuel bundle as well as the measured diameter data. Although the basic concept of the current modeling approach is simple, the diameter prediction results using the developed methodology showed very good agreement with the real data, compared to the existing methodology.