Comparison of Source Term Assessment of the Release of Severe Accident Before and After the Fukushima Accident

Seunggi Jeong,Byungchae Lee,Jihyun Yu,Jonghoa Kim,Jangsoo Suh 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

Attention has been paid to the source term released after Chernobyl and Three Mile Island (TMI), which were the representative accidents of nuclear power plants, and has been studied several times in order to predict and evaluate radiation source term, which can be released in the event of a virtual accident. In particular, the impact of the accident was assessed on the basis of Deterministic Safety Analysis (DSA) and after the WASH-1400, the technology of the Probabilistic Safety Assessment (PSA) was introduced, supplementing safety by taking into account the existence of uncertainty. After the Fukushima accident, a SOARCA report was published to evaluate the specific classification of each type of accident, the realistic progress of the accident, and the leakage of radioactive materials. In this paper, the evaluation methodology and results of the source term of severe accident before and after the Fukushima accident were compared, and the evaluation methods applied to domestic nuclear power plants were compared. Prior to the Fukushima accident, the behavior of the accident and source term were evaluated for Loss of Coolant Accident (LOCA), which led to design based accidents, Total Loss of Feed Water (TLOFW) followed by Station Blackout (SBO) the results were compared to Chernobyl and TMI based on the resulting data to evaluate safety and reliability. After the Fukushima accident, the Interfacing System Loss of Coolant Accident (ISLOCA) and the Steam Generator Tube Rupture (SGTR), which is classified as containment’s bypass accident, were included for predictive assessment. This is due to the analysis that the risk of cancer and early mortality are affected. MACST facilities and strategies were added to domestic nuclear power plants, and accidents with a high core damage frequency were mainly interpreted. In addition, source term was evaluated with the addition of a Basement Melt-Through (BMT) accident that had not previously been considered as a focus. As a result of the comparison of source term evaluation, accidents can be caused by a number of unidentified problems, and Korea’s experience on Level 2 and 3 has not been accumulated, making it difficult to predict the results of source term evaluation or lack of reliability.

Performance Evaluation by Measurement Conditions for Wide Area Site Exploration Design

Seunggi Jeong,Jihyun Yu,Byungchae Lee,Jonghoa Kim,Jangsoo Suh 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

Due to the Fukushima nuclear accident, a large amount of radioactive material was released into the atmosphere, and consequently, it spread over a wide area and was deposited into the soil. As a result of this, a wide area of radioactive contamination site was created. Due to the contaminated site, the need for research on various exploration platforms for efficient situation management and field response is being emphasized. Backpack-type radiation survey & monitoring equipment is useful for creating a contamination maps containing information such as Dose Rate, Radionuclide, Activity Concentration accompanied by spatial analysis when performing a Scan Survey that moves with a backpack on a wide area site. contamination maps are based on accurate radiological characteristic information. However, there is a problem in that the accuracy of the evaluation results is lowered due to changes in environment conditions or the variability of the dose rate and counting rate during scan survey. This problem should be solved by applying the influence of each variable to the underlying data. However, prior to this, it is most important to prepare the base underlying first. And this can be obtained through evaluation of detection performance through static survey. Therefore, in this study, the change in detection efficiency for the measurement height and radius of the backpack-type radiation survey & monitoring equipment based on the 3×3 NaI(Ti) detector was evaluated. First, the height of the source and Backpack-type radiation survey & monitoring equipment was evaluated from 0 cm to 1 m, which is the height of the soil and detector when an adult male wears a backpack. The experiment was conducted using the 137Cs (383 kBq) point source, which is a nuclide mainly detected at the contaminated site. The measurement time was measured five times per one minute, considering that it was backpack-type equipment and a future scan survey. In addition, in order to evaluate the detection radius, the measurement was performed by changing the measurement distance up to 5 m at intervals of 50 cm. As a result of evaluating the detection performance of the backpack-type radiation surveys & monitoring equipment, it was confirmed that increasing the detection height and radius reduces the count rate in the form of an exponential function. In addition, it was confirmed that the detected radius varies depending on the height. Based on these results, we plan to conduct additional research to understand the scan survey and its sensitivity to various factors. Through this, the company plans to develop various models for exploring the site by improving the accuracy of backpack-type radiation surveys & monitoring equipment.

Erythema infectiosum: a retrospective clinical study of 83 cases

( Hongpil Jeong ),( Hanhim Jeong ),( Sunyoung Jo ),( Seunggi Hong ),( Jaewan Go ),( Hyunjoo Lee ),( Eunphil Heo ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.2

Background: Erythema infectiosum (EI) is a childhood illness commonly observed among school-aged children and is caused by the infection of Human parvovirus B19 (B19). In atypical forms, it is often difficult to distinguish from other viral diseases, drug eruption, and erythema multiforme. Objectives: The purpose of this study was to analyze clinical characteristic of EI. Methods: We retrospectively reviewed the medical records of the patients who suspected for EI from last 10 years (January 2009 - August 2019) in our hospital found eighty three patients. Results: A total of 83 patients (male to female ratio, 1.08) with a mean age of 8.45 years (range, 0.7 ~ 43 years) were evaluated. Rash started from face in 32 cases (38.6%), trunk in 16 cases (19.3%) and simultaneously in the whole body in 35 cases. Most patients has similar lapse of illness, resolved skin lesion in 1-2 weeks without other complications. Four cases had arthralgia, and thirty eight patients had upper respiratory tract infection symptoms with mild fever. We identified B19 DNA by PCR from serum in 27 cases (33%), results of test were positive in 18 and negative in 9. In these patients needed for differential diagnosis with drug eruption (3 cases), viral exanthem (8 cases) and acute urticaria (4 cases). Conclusion: EI is usually diagnosed on clinical characteristics. But significant number of atypical EI can be observed, which should be differentiated from other diseases. In these cases, serum B19 PCR aid confirmation of EI.

Relationship between clinical findings and ophthalmological features in facial herpes zoster patients

( Hanhim Jeong ),( Hongpil Jeong ),( Sunyoung Jo ),( Seunggi Hong ),( Hyun Joo Lee ),( Eunphil Heo ),( Jae Wan Go ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.2

Background: Facial herpes zoster can be accompanied with several complications such as postherpetic neuralgia(PHN), facial palsy and ocular complications. Ophthalmologic consultation is important to figure out the presence of ocular complications. Objectives: The aim of this study is to evaluate the risk factors and clinical features of the facial herpes zoster patients suspected of ocular complications. Methods: We analyzed the records of 146 facial herpes zoster patients who received ophthalmologic consultation from 2014 to 2019. We investigated the patient’s age, sex, dermatomal distribution, delayed time to treatment. Results: Among the age groups, the incidence rate of ocular complications (83.8%) and severe ocular complications(SOC, 37.8%) were highest in the fifth decade. Herpes zoster involving both the ophthalmic(V1) and the maxillary(V2) nerve showed a higher incidence rate of ocular complications(89.7%) and SOC(50.0%) than those involving only V1(p=0.031, p=0.025). Patients who received antiviral treatment within 4days showed lower rates of ocular complications(52.3%) and SOC(20.0%) than patients who received treatment after 5days(p<0.001, p=0.019). The incidence of PHN were higher in those older than 60years(55.7%, p<0.001) and treated more than 4days after the onset(46.9%, p=0.002). Conclusion: Facial herpes zoster can lead to ocular complications and PHN. To decrease the risk of them, it is important to provide an early antiviral treatment and ophthalmologic consultatation.

FW-H 방법을 이용한 잠수함 표면 처리에 따른 소음 전산 해석

김승기(Seunggi Kim),유재영(Jaiyoung Ryu) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11

Submarine has been performed for national defense activities representatively. Underwater Radiated Noise (URN) which emitted during underwater vehicle operation is directly related to the survivability of the underwater vehicle. This study focused on examining the effects of surface treatment on noise aspects in submarine. Numerical simulations were conducted for two cases : smooth surface as a reference case, and V-type riblet. To solve the incompressible fluid flow passing the submarine, the Reynolds-averaged Navier-Stokes equation coupled with the k-ω SST turbulence model was used. As a result of examining the noise radiation around the submarine, it was confirmed that it was necessary to pay attention to the noise radiation effect in the middle part of the submarine body. And the results indicate that overall sound pressure level can be reduced about maximum 4 dB at far-field by applying riblet surface. This study provides more enhanced understanding about the surface design on underwater vehicles to reduce underwater radiated noise.

Treatment of infantile hemangiomas with topical timolol agent - single center experience

( Seunggi Hong ),( Sunyoung Jo ),( Hanhim Jeong ),( Eunphil Heo ),( Kiwoong Ro ) 대한피부과학회 2018 대한피부과학회 학술발표대회집 Vol.70 No.2

Background: Systemic propranolol is treatment of choice of large and complicated infantile hemangiomas (IHs), but there are safety concerns. Topical uses of the nonselective beta-blocker timolol can also effective treatment of IHs by inhibit the growth and promote regression. Objectives: The purpose of this study was to evaluate efficacy and safety of topical timolol for managing IHs through a Korean single center experience. Methods: A total of 25 patients with IHs were applied with timolol 0.5% ophthalmic solution twice a day without any other therapeutic modalities. Outcomes were defined in terms of decrease of thickness and reduction of red color in a semiquantitative manner: almost complete reduction (>80%), paler and thinner (50-80%), slightly paler and thinner (<50%), no change, and further growth. Results: The duration of timolol therapy ranged from 8 to 60 weeks (mean: 22.7 weeks). Among 25 patients, 4 patients were shown almost complete reduction, 14 patients were shown paler and thinner, 3 patients were shown slightly paler and thinner, 2 patients were shown no change, and 2 patients were shown further growth. Twenty-one (84%) of the 25 patients reported symptomatic improvement associated with growth arrest of IH and a reduction in thickness and redness. During topical timolol treatment, any systemic absorption adverse events were not observed. Conclusion: In this study, topical timolol is safe and efficacious topical therapy for IHs.

Reaction Mechanism of Area-Selective Atomic Layer Deposition for Al₂O₃ Nanopatterns

Seo, Seunggi,Yeo, Byung Chul,Han, Sang Soo,Yoon, Chang Mo,Yang, Joon Young,Yoon, Jonggeun,Yoo, Choongkeun,Kim, Ho-jin,Lee, Yong-baek,Lee, Su Jeong,Myoung, Jae-Min,Lee, Han-Bo-Ram,Kim, Woo-Hee,Oh, Il-K American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.47

<P>The reaction mechanism of area-selective atomic layer deposition (AS-ALD) of Al2O3 thin films using self-assembled monolayers (SAMs) was systematically investigated by theoretical and experimental studies. Trimethylaluminum (TMA) and H2O were used as the precursor and oxidant, respectively, with octadecylphosphonic acid (ODPA) as an SAM to block Al2O3 film formation. However, Al2O3 layers began to form on the ODPA SAMs after several cycles, despite reports that CH3-tenninated SAMs cannot react with TMA. We showed that TMA does not react chemically with the SAM but is physically adsorbed, acting as a nucleation site for Al2O3 film growth. Moreover, the amount of physisorbed TMA was affected by the partial pressure. By controlling it, we developed a new AS-ALD Al2O3 process with high selectivity, which produces films of similar to 60 nm thickness over 370 cycles. The successful deposition of Al2O3 thin film patterns using this process is a breakthrough technique in the field of nanotechnology.</P>

잔류응력이 배관 응력부식균열 제작에 미치는 영향에 관한 연구

배승기(Seunggi Bae),김재성(Jaeseong Kim),정상혁(Sanghyeok Jeong),이찬희(Chanhee Lee) 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11

전 세계 가동 중인 원자력발전소에서 많이 발생하는 응력부식균열은 평균적으로 가동 후 20년 이후부터 지속적으로 발생하고 있어 노후화된 원전에서는 안전사고 발생에 위협적인 존재로 인식되고 있다. 응력부식균열은 인장 잔류응력, 재료의 민감도, 수화학적 환경의 3가지 조건이 모두 형성될 경우에만 발생하는 것으로 잘 알려져 있다. 원전 구조물에서 인장 잔류응력이 가장 많이 존재하는 곳은 용접부 배관으로 용접 중 냉각에 의해 수축되는 배관 양끝단이 고정되어 있어 변형이 발생하지 않으며 이는 모두 인장 잔류응력으로 바뀌게 된다. 인장 잔류응력이 많이 존재하고 있는 용접부의 표면을 인장잔류응력이 아닌 압축잔류응력으로 바꾸는 방법으로 오버레이 용접, 레이저 피닝, 워터젯 피닝, UNSM(ultrasonic nanocrystal surface modification)처리, 고주파 피닝(high frequency peening), 진동응력완화(vibration stress relaxation), PWHT(post weld heat treatment), MSIP(mechanical stress improvement process), pipe lock, IHSI(induction heating stress improvement), 정수압 실험(hydro-static proof test), LPB(low plasticity burning) 등의 다양한 연구들이 진행되고 있다. 하지만, 이러한 연구들은 실제 배관재 용접부에서 응력부식균열 발생 경향을 실험적으로 확인한 연구보다는 대부분 해석적, 간접적인 방법을 적용하여 진행되었다. 이에 본 연구에서는 6인치 STS 304 배관 용접부와 용접부 표면에 초음파 피닝을 적용한 시험편에 직접 관통 응력부식균열을 제작하여 그 특성을 확인하였다. 배관 용접부 표면의 잔류응력을 확인하기 위해 hole drilling 기법을 적용하였으며, 재료적인 특성 변화를 검토하기 위해 표면 및 두께 방향으로 OM과 SEM 촬영을 진행하였다.

A case of Mycobacterium massiliense soft tissue infection

( Hanhim Jeong ),( Sunyoung Jo ),( Seunggi Hong ),( Jaewan Go ),( Eunphil Heo ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.1

Mycobacterium massiliense is a new species in the Mycobacterium chelonae-Mycobacterium abscessus group, which was first isolated in 2004 from the sputum of a patient with hemoptoic pneumonia. It is an acid-fast bacillus that is classified as a pathogenic ‘rapid growing’ nontuberculous mycobacteria. A 64-year-old female patient presented with a tender, erythematous to brownish subcutaneous nodule located on her left posterolateral thigh for 2 weeks. She had no history of medical procedure or trauma and the symptom was refractory to antibiotic medication. Skin biopsy and bacterial, fungus and AFB culture were done in the lesion. Bacterial and fungus culture of the pus specimen revealed negative results. AFB culture stain was positive, and Mycobacterium massiliense was identified. It showed resistance to ciprofloxacin, doxycycline, and trimethoprime/sulfamethoxazole. Histopathologically, it revealed epidermal hyperplasia and a neutrophilic abscess with granulomatous inflammation. AFB and PAS staining results were negative. The patient was treated with a combination of amikacin, cefoxitin and clarithromycin for first 4 weeks followed by oral clarithromycin monotherapy for several months. The skin lesion showed improvement after the treatment.

A case of myxoid intravascular fasciitis

( Hanhim Jeong ),( Sunyoung Jo ),( Seunggi Hong ),( Jaewan Go ),( Eunphil Heo ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.1

Nodular fasciitis is a common reactive proliferation arising in the subcutaneous tissue, muscle and fascia. Intravascular fasciitis is a rare variant of nodular fasciitis, seen in less than 3% of nodular fasciitis. It is presented in a small-to medium sized vessels and shares similar histopathology of nodular fasciitis, composed of high density of fibroblasts. A 16-year-old female patient presented with an asymptomatic erythematous patch with linear tortuous subcutaneous nodules on her left posterior thigh. On physical examination, prominent telangiectasia were found within the hyperpigmented lesion and multiple subcutaneous nodules were touched smoothly with cartilage hardness in the lesion. Punch biopsy was done in the nodular lesion. Histologically, a welldemarcated nodule was found in the deep dermis without signs of inflammation around it. Only in the nodular lesion, myxoid changes with sparse spindle cells were found. Immunohistochemical staining results showed that most of the spindle cells were positive for smooth muscle actin. The lesion also showed strong positive staining with Alcian blue. A diagnosis of myxoid intravascular fasciitis was made based on the clinical and pathological findings. The patient is planning to undergo surgery when symptom arises. Herein we report a rare case of intravascular fasciitis that showed a feature of prominent mucin deposition in the lesion, a case of myxoid intravascular fasciitis.