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Kwon, Hyuk-Sung,Ro, Jong-Suk,Jung, Hyun-Kyo IEEE 2018 IEEE transactions on magnetics Vol.54 No.12
<P>Optimization of an electric machine is a nonlinear multi-variable problem. For optimization of the nonlinear multi-variable problem, many function evaluations are required, which in turn requires much time. To address this problem, we propose a novel optimization algorithm of which the convergence speed, accuracy, and reliability are superior compared to those of widely used conventional algorithms. The performance of the proposed algorithm is verified through mathematical test functions and applied to a practical optimization scenario of cogging torque minimization for an interior permanent magnet synchronous machine.</P>
Lessons Learned in Improvement Work of Fuel Handling Equipment at Operating Nuclear Power Plants
Sang-Gyoon Chang,Won-Bae Park,Min-Gyu Kim,Dae-Hyuk Kwon 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2
The purpose of this study is to provide lessons learned in the experience of improvement work of fuel handling equipment at operating nuclear power plants. The upgrade of fuel handling equipment for safety enhancement and performance improvement has been going on for 15 years since the early 2000’s. The main goal is to increase fuel loading/unloading capability of the equipment from about 2.5 fuel assemblies per hour to more than six (6). It is achieved with sequential operations of three (3) fuel handling equipment, which consists of the refueling machine, the fuel transfer system and the spent fuel handling machine. The scope of the upgrade for fuel handling equipment is summarized as follows. The PC data control system based on PLC for interlocks and high speed motor drive system is introduced for better operating efficiency. The motors and drives for bridge, trolley, and hoist are replaced with AC servomotors and drivers, respectively. The fuel transfer system has an auto-initiation feature operating from the refueling machine or the spent fuel handling machine. The winch motor and drive for the carriage of fuel transfer system is also replaced with AC servomotors and drivers. And some of HPU (hydraulic power units) equipment for each building (reactor containment building and fuel handling building) are replaced to improve their function. The considerations for improvement of fuel handling equipment are as belows. 1) Fuel handling should be consistent with the instructions provided by the fuel designer and/or manufacturer, which are for Standard type fuel and Westinghouse type fuel, used in domestic nuclear power plants. Each fuel has unique design characteristics, which are PLC setpoints for overload and underload, slow speed zones for a bridge, trolley and hoist, allowable acceleration/deceleration value in handling, hoist elevation and manual speed in off-index operation at reactor. 2) The interlock system should be designed in accordance with design criteria specified by the utilities of nuclear power plant. 3) Performance should be improved according to the operating characteristics of the fuel handling equipment. High-speed and optimization of FTS upender and carriage are essential for operating performance so that its modification should be considered first. And the low speed and range in the operation mechanism of the hoist should be designed to comply with guidelines. 4) The accident analysis through self-diagnosis function and operation history in modification at domestic operating nuclear power plants would be good lessons learned. It is advisable to utilize such various information as it can help to improve reliability of nuclear fuel handling operation and power plant operation rate.
Leptomeningeal carcinomatosis of gastric cancer: Multi-center retrospective analysis of 54 cases (초)
( Sung Yong Oh ),( Sung Hyun Kim ),( Hyuk Chan Kwon ),( In Gyu Hwang ),( Joung Soon Jang ),( Gyeong Won Lee ),( Jung Hun Kang ),( Su Jin Lee ),( Jee Yun Lee ),( Ho Yeong Lim ),( Young Suk Park ),( Won 대한내과학회 2008 대한내과학회지 Vol.75 No.1S
Hyuk Sung Kwon,Ha-rin Yang,Kyungtaek Yun,Jong Sook Baek,Young Un Kim,Seongho Park,Hojin Choi 대한신경정신의학회 2020 PSYCHIATRY INVESTIGATION Vol.17 No.8
Objective This study aimed to evaluate the effect of cognitive training programs on the progression of dementia in patients with early stage Alzheimer’s disease dementia (ADD) at the day care center. Methods From January 2015 to December 2018, a total of 119 patients with early ADD were evaluated. All subjects were classified into two groups according to participate in cognitive training program in addition to usual standard clinical care. Changes in scores for minimental status examination-dementia screening (MMSE-DS) and clinical dementia rating-sum of boxes (CDR-SOB) during the 12 months were compared between two groups. Multivariable logistic regression analyses were performed. Results As compared to case-subjects (n=43), the MMSE-DS and CDR-SOB scores were significantly worse at 12 months in the control- subjects (n=76). A statistically significant difference between the two groups was observed due to changes in MMSE-DS (p=0.012) and CDR-SOB (p<0.001) scores. Multivariable logistic regression analysis showed that the cognitive training program (odds ratio and 95% confidence interval: 0.225, 0.070-0.725) was independently associated with less progression of ADD. Conclusion The cognitive training program was associated with benefits in maintaining cognitive function for patients with earlystage ADD that were receiving medical treatment.
Kwon Doo Hyuk,Jang Seong Hwa,Park Hyungjong,Sohn Sung-Il,Hong Jeong-Ho 대한의학회 2022 Journal of Korean medical science Vol.37 No.19
Background: Intravenous recombinant tissue plasminogen activator (IV rtPA) is the mainstay of treatment for acute ischemic stroke to recanalize thrombosed intracranial vessels within 4.5 hours. Emergency carotid artery stenting for the treatment of acute stroke due to stenoocclusion of the proximal internal carotid artery (ICA) can improve symptoms, prevent neurological deterioration, and reduce recurrent stroke risk. The feasibility and safety of the combination therapy of IV rtPA and urgent carotid artery stenting have not been established. Methods: From November 2005 to October 2020, we retrospectively assessed patients who had undergone emergent carotid artery stenting after IV rtPA for hyperacute ischemic stroke due to steno-occlusive proximal ICA lesion. Hemorrhagic transformation, successful recanalization, modified Rankin Scale (mRS) score at 90 days, and stent patency at 3 and 12 months or longer were evaluated. Favorable outcome was defined as a 90-days mRS score of ≤ 2. Results: Nineteen patients with hyperacute stroke had undergone emergent carotid artery stenting after IV rtPA therapy. Their median age was 70 (67.5–73.5) years (94.7% men). Among 15 patients with an additional intracranial occlusion after flow restoration in the proximal ICA, a modified TICI grade ≥ 2b was achieved in 11 patients (73.3%). Hemorrhagic transformation occurred in five patients (26.3%); mortality rate was 5.7%. Eleven patients (57.9%) had favorable outcomes at 90 days. Stent patients (94.1%) maintained stent patency for ≥ 12 months. Conclusion: We showed that emergent carotid artery stenting after IV rtPA therapy for hyperacute stroke caused by atherosclerotic proximal ICA steno-occlusion was feasible and safe.
Dietary Exposure and Risk Assessment of Mercury from the Korean Total Diet Study
Kwon, Young Min,Lee, Haeng Shin,Yoo, Dong Chul,Kim, Chun Huem,Kim, Gi Sun,Kim, Ji Ae,Lee, Yu Na,Kim, Young Soon,Kang, Kyung Mo,No, Ki Mi,Paek, Ock Jin,Seo, Jung Hyuk,Choi, Hoon,Park, Sung Kug,Choi, Do Informa UK (TaylorFrancis) 2009 Journal of toxicology and environmental health. Pa Vol.72 No.21
<P>As a national project, obtaining information on the amount of heavy metal exposure of individuals through food intake is an important basic parameter for risk assessment. This study was conducted to evaluate dietary exposure levels and various risks from mercury (Hg) in Korean foods. In total, 342 samples comprising 114 food items were collected and then cooked prior to analysis. As found by Hg analysis, the mean content of metal in the fish and shellfish group was highest among the 15 Korean food groups. The total daily amount of Hg intake from typical Korean foods was 2.40 mug/person/d. The daily amount (mug/person/d) of Hg intake from each food group was 0.155 in grains and cereals, 0.008 potatoes and starch, 0.005 sugars and sweets, 0.0093 pulses, 0.0018 nuts and seeds, 0.203 vegetables, 0.027 fruits, 0.021 meats and poultry, 0.004 eggs, 1.826 fish and shellfish, 0.022 seaweed, 0.043 milk and dairy products, 0.008 oils and fats, 0.042 beverages, and 0.023 seasonings. The fish and shellfish group contributed most to total dietary intake at 76%. For risk assessment, probable daily intake (PDI) was calculated and compared with provisional tolerable weekly intake (PTWI) of the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The level of Hg intake through fish and shellfish of 0.001 mg/kg body weight bw/wk corresponded to 4.54% of the PTWI value of 0.005 mg/kg bw/wk, the safety standard for JECFA. The level of Hg intake through selected foods from the Food list for Koreans was 0.001 mg/kg bw/wk, corresponding to 5.95% of PTWI value. Therefore, overall intake was at levels below the recommended JECFA levels. The relative gender Hg hazard from Korean foods was 6.26% and 5.5% for males and females, respectively. The relative age Hg hazard from Korean foods was, 8.9% in those 3-6 yr old, 6.7% in those 7-12 yr old, 5.2% in those 13-19 yr old, 5.9% in those 20-29 yr old, 6.3% in those 30-49 yr old, 5.6% in those ages 50-64 yr, and 3.7% in the group of those over 65 yr of age. Relative regional Hg hazard from Korean foods was 6.3% in urban versus 5.5% in rural areas. Thus, the amount of Hg intake through consumption of Korean foods was found to be at a relatively safe level. These data may be thus used to establish safety standards for fish and shellfish consumption.</P>
( Sung Joon Park ),( Yoon Soo Jang ),( Tae Hyuk Koh ),( Young A Kwon ),( Sang Wroul Song ) 대한안과학회 2011 Korean Journal of Ophthalmology Vol.25 No.6
This research focuses on four cases of patients having undergone eximer laser photorefractive surgery who were diagnosed with adenoviral keratoconjunctivitis during the postoperative period and who later developed epidemic keratoconjunctivitis (EKC)-like keratitis. Two of the patients had undergone laser-assisted subepithelial keratectomy (LASEK), one had undergone laser in situ keratomileusis and one had photorefractive keratectomy. After the surgery adenoviral keratoconjunctivitis and recurrent late-developing EKC-like keratitis were observed in the patients. Recurrent late-developing EKC-like keratitis occurred in one of the patients, who had received LASEK as many as three times. The others had only one or two episodes.The corneal infiltrates of keratitis mainly occurred in the central cornea. Successful resolution of recurrent late-developing EKC-like keratitis was achieved through the use of topical steroids without sequelae and the final best-corrected visual acuity was as good as the base line. These keratitis infiltrates have been presumed to represent an immune response to the suspected adenoviral antigens deposited in corneal stroma during the primary adenoviral infection. Previous reports argued that patients with a history of adenoviral ketatoconjunctivitis were succeptible to adenoviral keratoconjunctivitis becoming reactivated; however, in our research, our patients had their first adenoviral infections after the eximer laser photorefractive surgery and reactivation was confirmed. We recommend that attention be paid to adenoviral infection after laser refractive operations, because these patients seem to have more frequent recurrences.