• Corrosion Science and Technology
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• 제20권4호
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• pp.189-195
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• 2021

A technology for designing and licensing a dedicated radiation shielding facility needs to be developed for safe and efficient operation an R&D center. Technology development is important for smooth operation of such facilities. Causes of damage to internal structures (such as baffle former bolt (BFB) of pressurized water reactor) of a nuclear power reactor should be analyzed along with prevention and countermeasures for similar cases of other plants. It is important to develop technologies that can comprehensively analyze various characteristics of internal structures of long term operated reactors. In high-temperature, high-pressure operating environment of nuclear power plants, cases of BFB cracks caused by irradiated assisted stress corrosion cracks (IASCC) have been reported overseas. The integrity of a reactor's internal structure has emerged as an important issue. Identifying the cause of the defect is requested by the Korean regulatory agency. It is also important to secure a foundation for testing technology to demonstrate the operating environment for medium-level irradiated testing materials. The demonstration testing facility can be used for research on material utilization of the plant, which might have highest fluence on the internal structure of a reactor globally.

• 대한방사선기술학회지:방사선기술과학
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• 제42권3호
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• pp.231-238
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• 2019

Medical institutions are abundant in human resources and have a unique structure with diverse professions and various organizational cultures coexist. This organizational culture influences organizational effectiveness and influences the effectiveness of the organization as a factor of leadership and organizational culture. Leadership is an important factor in linking employee behavior to organizational commitment to achieve job satisfaction. The purpose of this study was to analyze the effect of organizational effectiveness on organizational culture, leadership perception, and job stress in a special organization called radiologist. As a result, organizational culture and transformational leadership showed high correlation with 0.627. Among the organizational effectiveness variables, organizational commitment showed the highest influence with transformational leadership(${\beta}=0.284$, p<0.001), and job satisfaction was also the highest with transformational leadership (${\beta}=0.440$, p<0.001). The results showed that the expectation of transformational leadership affects organizational commitment and job satisfaction. In order to expect a positive change in the effectiveness of the organization, the radiologist culture requires an organizational culture that can fully demonstrate autonomy and creativity, and transformational leadership is required for this.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2823-2834
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• 2023

Austenitic stainless steel welds (ASSWs) of nuclear components undergo aging-related degradations caused by high temperature and neutron radiation. Since irradiation leads to the change of material characteristics, relevant quantification is important for long-term operation, but limitations exist. Although ion irradiation is utilized to emulate neutron irradiation, its penetration depth is too shallow to measure bulk properties. In this study, a systematic approach was suggested to estimate mechanical properties of ion irradiated 308 ASSW. First of all, weld specimens were irradiated by 2 MeV proton to 1 and 10 dpa. Microstructure evolutions due to irradiation in δ-ferrite and austenite phases were characterized and micropillar compression tests were performed. In succession, dislocation density based stress-strain (S-S) relationships and quantification models of irradiation defects were adopted to define phases in finite element analyses. Resultant microscopic S-S curves were compared to verify material parameters. Finally, macroscopic behaviors were calculated by multiscale simulations using real microstructure based representative volume element (RVE). Validity of the approach was verified for the unirradiated specimens such that the estimated S-S curves and 0.2% offset yield strengths (YSs) which was 363.14 MPa were in 10% agreement with test. For irradiated specimens, the estimated YS were 917.41 MPa in 9% agreement.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.927-938
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• 2023

The blanket plays an important role in fusion reactor and stands extremely high thermal and electromagnetic loads during operation situation and plasma disruption event, brings the need for precise thermal and electromagnetic analysis. Since the thermal field and EM field interact with each other nonlinearly, we develop a method of electromagnetic-thermal two-way coupling by using finite element software COMSOL. The coupling analyses of blanket under steady state and MD event are implemented and the results are analyzed. For steady state, the influences of coupling effects are relatively small but still recommended to be considered for a high precision analysis. The influence of thermal field on EM field can't be ignored under MD events. The variation of force density could cause a significant change in stress in certain parts of blanket. The influence of Joule heat during MD event is negligible, yet the potential temperature rise caused by induced current after MD event still needs to be researched.

• 한국해양공학회지
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• 제37권3호
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• pp.111-121
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• 2023

This paper intends to introduce the applicability of HydroQus to a problem of a tanker collision against a semi-submersible type floating offshore wind turbine (FOWT). HydroQus is a plug-in based on potential flow theory that generates interactive hydroforces in a commercial Finite element analysis (FEA) code Abaqus/Explicit. Frequency response analyses were conducted for a 10MW capacity FOWT to obtain hydrostatic and hydrodynamic constants. The tanker was modeled with rigid elements, while elastic-plastic elements were used for the FOWT. Mooring chains were modeled to implement station keeping ability of the FOWT. Two types of fracture models were considered: constant failure strain model and combined failure strain model HC-LN model composed of Hosford-Coulomb (HC) model & localized necking (LN) model. The damage extents were evaluated by hydroforces and failure strain models. The largest equivalent plastic strain observed in the cases where both restoring force and radiation force were considered. Stress triaxiality and damage indicator analysis showed that the application of HC-LN model was suitable. It could be stated that applications of suitable failure strain model and hydrodynamics into the collision simulations were of importance.

• BMB Reports
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• 제56권11호
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• pp.612-617
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• 2023

Pleiotropic regulator 1 (PLRG1), a highly conserved element in the spliceosome, can form a NineTeen Complex (NTC) with Prp19, SPF27, and CDC5L. This complex plays crucial roles in both pre-mRNA splicing and DNA repair processes. Here, we provide evidence that PLRG1 has a multifaceted impact on cancer cell proliferation. Comparing its expression levels in cancer and normal cells, we observed that PLRG1 was upregulated in various tumor tissues and cell lines. Knockdown of PLRG1 resulted in tumor-specific cell death. Depletion of PLRG1 had notable effects, including mitotic arrest, microtubule instability, endoplasmic reticulum (ER) stress, and accumulation of autophagy, ultimately culminating in apoptosis. Our results also demonstrated that PLRG1 downregulation contributed to DNA damage in cancer cells, which we confirmed through experimental validation as DNA repair impairment. Interestingly, when PLRG1 was decreased in normal cells, it induced G1 arrest as a self-protective mechanism, distinguishing it from effects observed in cancer cells. These results highlight multifaceted impacts of PLRG1 in cancer and underscore its potential as a novel anti-cancer strategy by selectively targeting cancer cells.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2020년도 춘계학술대회
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• pp.74-74
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• 2020

Skin is continuously exposed to a variety of environmental stresses, including ultraviolet (UV) radiation. UVB is an inherent component of sunlight that crosses the epidermis and reaches the upper dermis, leading to increased oxidative stress, activation of inflammatory response and accumulation of DNA damage among other effects. In the present study, the anti-wrinkle mechanism of Acorus gramineus callus culture supernatant (GB-AGS-PSC) was elucidated in UVB treated HaCaT keratinocytes. GB-AGS-PSC prevented the matrix metalloprotease 1 (MMP-1), elastin, and pro-collagen product and cytotoxicity and SOD inhibition. Quantitative polymerase chain reaction showed that GB-AGS-PSC-treated cells displayed dose-dependent increase in messenger RNA expression levels of Aquaporin 3 (AQP3), Keratin 1(KRT1), fillagrin, and hyaluronan synthase-2 (HAS 2) and decreased expression levels of matrix metalloproteinase-3, -9, and -13 in UVB treated HaCaT keratinocytes. Additionally, GB-AGS-PSC suppressed TNF-α, IL-1β, and IL-8 product for inflammatory responses in UVB treated HaCaT keratinocytes. Therefore, GB-AGS-PSC may be useful as an anti-photoaging resource for the skin.

• 치위생과학회지
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• 제10권4호
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• pp.265-271
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• 2010

본 연구는 구강보건의료기관에서 방사선 촬영을 하고 있는 치과위생사를 대상으로 방사선 노출에 대한 인지도와 지식을 살펴보았다. 그리고 치과방사선 피폭 대상인 환자와 보호자에 대한 관리 실태 및 근무환경에서 받는 직무스트레스를 조사한 후, 상호 변수 간의 관련성을 파악하기 위해 이메일과 등기우편을 통한 자기기입식 설문법에 의한 256명의 우편 설문조사 결과를 분석하여 다음과 같은 결과를 얻었다. 1. 치과방사선 안전관리 행태에서 최고점수 5점 만점에서 관련 지식은 3.11점, 인식 4.08점, 방사선안전관리 행위 3.43점으로 나타났다. 2. 치과위생사의 직무스트레스는 최고점수 5점 만점에서 2.63점으로 중등도 수준 이하로 나타났다. 3. 근무지별 방사선 피폭에 대한 인지도는 치과병원이 4.26점으로 가장 높았고, 보건(지)소가 3.95점으로 가장 낮았다(p=0.003). 4. 연령별 방사선 피폭에 대한 보호구 착용은 30-34세군만이 착용한다는 응답률이 66.7%로 높았다(p<0.001). 또한 근무지별로는 치과병원 근무자가 보호구 착용을 77.8%가 하고 있다고 응답하였고, 다른 집단은 착용하지 않는다는 응답률이 높았다(p<0.001). 5. 방사선 피폭에 대한 보호구 착용자가 방사선안전관리에 대한 지식, 인식, 자기 방어, 환자와 보호자에 대한 인식 및 보호 수준이 높았다(p<0.001). 6. 방사선 피폭에 대한 보호구 착용자가 비착용자에 비해 직무스트레스가 낮았다(p<0.001). 7. 연령별 직무스트레스는 25세 미만군이 3.10점으로 가장 높았고(p<0.001), 근무지별로는 대학병원 및 종합병원 근무자가 3.32점으로 가장 높았다(p<0.001). 8. 방사선 피폭에 대한 인식이 낮고(r=-0.133) 자기방어관리 수준은 높으며(r=-0.526), 환자와 보호자에 대한 인식 및 보호 수준이 높을수록(r=-0.403) 직무스트레스가 적었다. 이상의 결과에서 치과방사선 안전관리 행위가 적극적으로 시행될 때 직무스트레스는 감소할 수 있다고 여겨지며, 치과위생사의 건강증진을 위해 구강보건의료기관에서는 방사선보호장치 설치를 보다 강화하고 방사선 촬영 시 치과위생사는 갑상선 보호대 등 보호구 착용을 생활화할 수 있도록 교육 및 홍보를 활성화해야 한다고 제시된다.

• 에너지공학
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• 제23권3호
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• pp.186-190
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• 2014

원자력발전소는 냉각재상실사고(LOCA)와 같은 과도상태시 pH 조절을 통해 격납건물의 핵분열생성물(요오드) 제거 능력을 유지한다. 이와 더불어 격납건물 내부의 스테인레스강 기기들의 응력부식균열(Stress Corrosion Cracking)을 방지하고 알루미늄 또는 아연 부식에 의한 수소생성을 최소화할 수 있기 때문에 살수 및 집수조냉각수의 화학조건(pH) 조절능력이 요구된다. 현재 원전은 LOCA시 능동형 살수첨가제인 NaOH를 사용하여 격납건물 살수 및 집수조냉각수의 pH를 조절하도록 설계되어있다. 본 논문에서는 LOCA시 집수조냉각수의 pH를 분석하고, 살수화학조건 pH 관련 최신규제요건인 표준심사지침(SRP) 6.5.2에 따라 핵분열생성물제거상수 및 제염계수를 계산하였다. 분석결과, 격납건물집수조 pH는 8.09~9.67로서 설계기준을 만족한다. 그리고 격납건물살수계통에 의한 핵분열생성물 제거상수 및 제염계수는 원전 내환경기기검증을 위한 방사선환경 평가의 입력으로 제공된다.

• Journal of the korean society of oceanography
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• 제37권3호
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• pp.91-107
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• 2002

The wintertime upwind flow in the Yellow Sea has been investigated through a series of two-dimensional numerical experiments in an idealized basin. A total of 10 experiments have been carried out to examine the effects of wind forcing, bottom friction and the presence of oceanic currents sweeping the shelf of the East China Sea. A spatially uniform steady and periodic wind stresses are considered along with comparison of linear and quadratic formulations. The wind-driven flow in the absence of oceanic current has been computed using Proudman open boundary condition (POBC), while the wind-driven current in the presence of oceanic current has been computed using Flather’s radiation condition (FOBC). The oceanic currents to be prescribed at the open boundary have been simulated by specifying uniform sea level gradients across the Taiwan Strait and the eastern ECS shelf, Calculations show that, as seen in Lee et al. (2000), oceanic flow little penetrates into the Yellow Sea in the absence of wind forcing unless a unrealistically low rate of bottom frictional dissipation is assumed. Both steady and time-periodic wind stresses invoke the upwind flow along the central trough of the Yellow Sea, independently of the presence of the oceanic current. The presence of oceanic currents very marginally alters the north-south gradient of the sea surface elevation in the Yellow Sea. Changes in the intensity and direction of the wind-induced mean upwind flow are hardly noticeable in the Yellow Sea but are found to be significant near Cheju Island where the gradient is reduced and therewith contribution of Ekman transport increases. In case of steady wind forcing circulation patterns such as two gyres on the slope sides, a cyclonic gyre on the western slope and an anticyclonic gyre on the eastern slope persist and the upwind flow composes part of the cyclonic gyre in the Yellow Sea. While in case of the time-periodic wind stress the appearance and disappearance of the patterns are repeated according to the time variation of the wind stress and the upwind flow accordingly varies with phase delay, mostly intensifying near the time when the wind forcing is approximately near the middle of the decaying stage.