• 한국군사과학기술학회지
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• 제27권1호
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• pp.1-7
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• 2024

Weather is one of the main causes of aircraft accidents, and among the phenomena caused by weather, icing is a phenomenon in which an ice layer is formed when an object exposed to an atmosphere below a freezing temperature collides with supercooled water droplets. If this phenomenon occurs in the rotor blades, it causes defects such as severe vibration in the airframe and eventually leads to loss of control and an accident. Therefore, it is necessary to foresee the icing situation so that it can ascend and descend at an altitude without a freezing point. In this study, vibration data in normal and faulty conditions was acquired, data features were extracted, and vibration was predicted through deep learning-based algorithms such as CNN, LSTM, CNN-LSTM, Transformer, and TCN, and performance was compared to evaluate blade icing. A method for minimizing operating loss is suggested.

• Nuclear Engineering and Technology
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• 제56권9호
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• pp.3483-3490
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• 2024

The initial size distribution and morphological parameters of sodium aerosols are critical in evaluating the accidental suspended aerosol behaviour in Sodium-cooled Fast Reactor (SFR) containment. Mass-based measurements were more familiar in characterizing the sodium aerosols. Real-time number size distribution measurements are carried out in this study. The sensitivity analysis of sodium aerosol effective density (ρ_e) in deriving the actual number size distributions from the measured Aerodynamic Particle Size Distributions (APSD) and predicting suspended aerosol dynamics is presented. Tests are conducted in a 1 m³ chamber at 47 ± 3% RH for different initial mass concentrations (M₀) of 0.1, 1, and 2.9 g/m³. The initial APSDs measured just after the generation completions are observed to be polydisperse with the count median aerodynamic diameter (CMAD) < 1 ㎛. The literature reported ρ_e values of sodium aerosols, 2.27, 1.362, and 0.61 g/cm³ are used to derive mobility equivalent PSDs from APSD in each test. The real-time number concentration decay and size growth for four different PSDs are measured and compared with the estimate using nodal method-based code to ascertain the actual parameters. The validated parameters CMD = 0.66 ㎛, σ_g = 1.96, ρ_e = 1 g/cm³ and χ = 1 are used for improved estimation of sodium aerosol dynamics in Indian SFR containment with M₀ = 4 g/m³ for severe accident scenarios.

• Nuclear Engineering and Technology
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• 제56권10호
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• pp.4018-4030
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• 2024

The in-vessel retention through external reactor vessel cooling (IVR-ERVC) strategy is a key management strategy for early termination of a nuclear severe accident that can threaten the integrity of the reactor vessel. To simulate the physical phenomena of the molten corium, the smoothed particle hydrodynamic (SPH) method is utilized in this study. The SPH method is a Lagrangian computational fluid dynamic (CFD) method that can simulate multi-fluid stratification, turbulence, natural circulation, radiative heat transfer, thermal ablation, and crust formation. To address the external vessel cooling, it is coupled with a conventional 1-D nuclear system analysis method. The 1-D system analysis code can calculate the two-phase natural circulation of cooling water and the convective heat transfer on the external reactor vessel wall. These two simulation codes exchange the temperature and heat flux of the reactor vessel outer wall. This study numerically simulated the IVR-ERVC strategy for a Korean high-power reactor and compared it with the traditional lumped parameter method (LPM). Unlike LPM, this study provides localized detailed data about the thermal hydraulic behavior of molten corium and visualization of phenomena in the IVR-ERVC strategy. This enhances our understanding of the phenomena in IVR-ERVC strategy and introduces new perspectives.

• Nuclear Engineering and Technology
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• 제56권10호
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• pp.4077-4086
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• 2024

The natural circulation system has been widely studied for use in various applications because of its inherent advantage. However, it has a key weakness called flow instability that makes the system unstable. Through massive previous research, the mechanisms of flow instability were analyzed, but there was an ambiguous aspect related to the effect of experimental parameters on the phenomenon. Particularly, there has been no report on the heat transfer performance of the system when flow instability phenomena were present. In this study, thermal-hydraulic phenomena of a two-phase natural circulation system that functions as a passive containment cooling system (PCCS) was investigated according to experimental parameters, namely, the temperature boundary (120-158 ℃) and exit loss coefficient (0-34.5) under atmospheric pressure conditions. The experimental results showed five different flow types in the loop. The flow modes that occurred by the interaction between flashing and boiling were classified by referring to the mass flow rate, void fraction, and visualization data. The system was more unstable when the temperature boundary conditions increased, but it was more stable when the exit loss coefficient increased. These results have only been confirmed in our research. The reason for the results is that the flow conditions are located on the boundary between Density Wave Oscillation I and the stable flow region, and that boundary does not have clear criteria. In addition, comparing the heat transfer performance of a system by heat rate can confirm the effect of flow instability on the thermal performance of the passive cooling system. As a result, the high exit loss coefficient stabilizes the system better than the low case and has similar heat removal performance.

• 한국습지학회지
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• 제17권1호
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• pp.45-52
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• 2015

구미의 화학약품 제조업체 휴브글로브에서 불산 유출사고가 발생하고 약 1년 후인 2013년 8월 초 사고 발생 현장 주변에 성립한 식생 피해에 대한 조사를 통해 다음과 같은 결과를 얻었다. 소나무와 스트로브잣나무는 매우 심한 피해, 은행나무, 상수리나무, 리기다소나무, 왕버들, 무궁화 및 배롱나무는 심한 피해, 굴참나무, 참싸리 및 참억새는 중간수준의 피해 그리고 갈참나무, 청미래덩굴, 새, 아까시나무 및 오동은 가벼운 피해를 나타내었다. 우리는 피해 현장 주변에서 피해를 입지 않은 어떤 식물도 발견하지 못하였다. 이러한 결과는 불소가 대기, 토양 및 물에 오랫동안 남아 생태계의 모든 수준에 걸쳐 부정적인 영향을 미친다고 알려졌듯이 이 지역에서 지난 해 발생한 불소피해가 여전히 지속되고 있다는 것을 의미한다. 한편, 여천공업단지에서 조사된 결과에 의하면, 식물 잎에 포함된 불소 농도는 비료공장으로부터 거리에 따라 달라졌고 식생 피해는 그 농도에 비례하는 경향이었다. 이런 점에서 불산 유출사고 현장 주변 생태계에 잔존하는 불소의 제거 및 해독 대책이 시급히 요청되고 있다. 불소를 불활성화 시킬 수 있는 칼슘과 마그네슘을 함유하고 있는 돌로마이트의 시비가 그 피해를 완화시킬 수 있는 복원계획의 하나로 준비되었다. 그밖에 토양개량 효과를 증진시키기 위해 인산염 비료 시비가 복원계획으로 추가되었다. 나아가 우리는 불소피해를 완화시키기 위한 두 번째 대책으로 내성종의 도입을 추천하였다. 불소가스 피해로 고사된 나무들을 대체하여 새로운 숲을 만들기 위한 내성종으로 우리는 갈참나무를 추천하였고, 그 숲이 안정된 내부 환경을 확보하기 위한 망토군락을 이룰 식물 종으로는 청미래덩굴과 새를 추천하였다.

• 인터넷정보학회논문지
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• 제21권2호
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• pp.139-148
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• 2020

현재 우리 군은 과학과 기술의 발달, 2000년대 들어 급격히 심해진 저 출산율, 병 복무기간 단축 등으로 병력위주에서 장비위주로 첨단화, 고속화, 복잡화 되어가고 있다. 즉, 한 번의 실수로 많은 인명피해가 발생할 수 있는 실정이다. 선진국과 민간 안전교육 체계 및 교육성과 등을 분석해보면 군 안전 및 자살사고를 예방하기 위해서는 체험교육이 중요하며, 체계적이고 효율적인 체험교육을 위해서는 안전체험훈련장 건립이 필요함을 알 수 있었다. 지금 입대하고 있는 장병들은 일명 인터넷세대로 태어나면서부터 인터넷을 접하면서 성장하여 가상·증강현실(VR / AR)을 자유롭게 활용하고 있으며, 지금의 과학 기술 수준은 국민안전체험관의 체험실 대부분을 가상·증강현실로 대체할 수 있을 정도의 수준까지 발전하였다. 따라서 군 안전체험훈련장은 설치공간, 건립비, 유지비, 사용자 특성, 교육효과 등을 고려하여 '응급처치'처럼 모형이 효과적인 체험실 몇 개를 제외한 많은 체험실을 가상·증강현실로 건립할 필요성이 있다. 가상·증강현실(VR / AR) 기술의 발전, 국민안전체험관 운용실태, 군 부대 특성, 설치비 및 유지비 등을 고려하여 체험훈련 소요를 도출하였다. 그리고, 국민안전체험관 대비 저비용으로 효과적인 훈련성과를 달성할 수 있는 안전체험훈련장 구축방안과 부대별 교육인원 및 주변 여건에 부합한 안전체험훈련장 규모와 체험실 구성에 대해 제시하였다. 향후 이를 기반으로 안전체험훈련장을 구축하여 체험교육을 한다면 군 안전 및 자살사고를 예방하는데 기여하게 될 것이다.

• 대한소아치과학회지
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• 제26권1호
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• pp.96-102
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• 1999

외상으로 인해 치근 완성 여부가 불분명 한 완전 탈구된 치아를 재식한 후 18개월 여간 관찰하여 다음과 같은 결과를 얻었다. 1. 재식 초기의 염증성 치근 흡수는 수산화 칼슘을 사용한 근관치료로 억제될 수 있었다. 2. 치근 완성 여부가 불확실한 치아에서 조기 근관치료가 염증성 치근 흡수 및 유착의 방지에 더 큰 임상적 성공을 얻을 수 있었다. 따라서, 재식 당시 치근첨의 개방성 여부가 명확하지 않을 때에는 성인의 치료 지침에 따라 치료하는 것이 보다 효과적이며, 불가피 할 경우에는 환자 및 보호자의 철저한 교육에 뒤따른 정확한 내원 약속이 속발증을 최소화 할 수 있을 것으로 사료된다.

• 대한한방내과학회지
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• 제26권4호
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• pp.806-819
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• 2005

Objective : The purpose of this study is to investigate clinical characteristics and remedial value oriental medical therapy for sufferers of severe headache. Methods : On the authority of DongEuiBoCam, patients were classified into three groups: migraine, qi-syncope headache and phlegm-headache. All patients wert treated with acupuncture therapy and herb medicines. After that inquiry was made into the extent of improvement of headache. Results : 1. In accordance with the statistics, 56 cases(50.5%) had phlegm-syncope headache, 28 cases(25.2%) had qi-syncope headache and 27 cases(24.3%) had migraine. 2. The ratio between males and females was about 1:4. Most patients were in their forties. 3. 12 cases(31.6%) with migraine had pain only on the right side of the head, 20 cases(26.3%) with phlegm-syncope and 17 cases(45.6%) with qi-syncope headache suffered from the frontal lobe headache. 4. 8 cases(29.6%) with migraine had been suffering for a week or less, 12 cases(21.4%) with phlegm-syncope headache had been suffering for over six months and under one year and 6 cases(21.4%) with qi-syncupe headache had suffered over one year and under five. 5. Overwork and stress was deemed the main cause of migraine. Phlegm-syncope headache was also attributed to stress and tense situations. Qi-syncope headache was believed to be variously caused by traffic accident, noise, blood pressure and other reasons. 6. 46 cases(30%) felt dull headache and 32 cases(20.9%) felt dizzy. The common associated symptoms of migraine and qi-syncope headache included back, neck and shoulder pain and other pains. Dizziness was an especially prevalent symptom of phlegm-syncope headache. 7. After the oriental medical therapy, 12 cases(10.8%) almost entirely recovered, 50 cases(45%) were in about half as much pain, 45 cases(40.5%) improved little and 4 cases(3.6%) felt no improvement. Conclusions : The results support a role for oriental medical therapy in treatment of headache.

• Journal of Preventive Medicine and Public Health
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• 제26권4호
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• pp.587-598
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• 1993

Hydrofluoric acid is one of the strongest irritating, corrosive and poisonous inorganic chemicals. Hydrofluoric acid burns are occurring with ever-increasing frequency due to the wide use of this acid in industries. Hydrofluoric acid burns are characterized by severe progressive tissue destruction and excruciating pain due to the unique properties of the freely dissolvable fluoride ion. The authors reviewed medical records of 32 cases (36 spells) of hydrofluoric acid burns which occurred in a hydrofluoric acid manufacturing factory from Sep. 1, 1990 to June 30, 1993. The results are as follows; 1. Eleven measurements of air concentrations of hydrofluoric acid by detection tube method from 1990 to 1992 were all below TLV (Department of Labor, R.O. K). 2. There were 19 cases (22 spells) of hydrofluoric acid burns which occurred during the study period among regular employees. The overall incidence density of hydrofluoric acid was 17.8 cases (20.6 spells) per 100 person-year. Incidence density was 19.0 cases (22.0 spells) per 100 person-year among male workers and there were no female cases. Incidence density was 32.9 cases (38.3 spells) per 100 person-year among production workers and 1.9 cases (1.9 spells) per 100 person-years among management workers with the difference being statistically significant (P<0.01). 3. Of 32 cases (36 spells) of hydrofluoric acid burns among workers who were regularly employed or temporarily employed, 26 spells (81.2%) were between age 20 to 39. In 15 spells(41.7%) burns occurred between 12:00 and 17:59 with 16 spells(44.3%) having arrived at hospital within 2 hours after the accident. 4. Of 36 spells, the main cause of hydrofluoric acid burns were by splashes (8 spells, 22.2 %). The most frequent site of burns were fingers and pain was the most frequent symptom. Thirty spells (83.3%) of the hydrofluoric acid burns were treated with local injection of antidote (calcium gluconate). Complete recovery without scarring were observed in most of the cases (34 out of 36 cases, 94.4%). The study results suggest that to prevent hydrofluoric acid burns, environmental control and the wearing of hydrofluoric acid resistant protective clothes and gloves are important. It is also stressed that establishment of an emergency management and a transfer system for hydrofluoric acid burn victims is necessary.

• Journal of Chest Surgery
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• 제31권10호
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• pp.1004-1008
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• 1998

본 논문은 동맥관개존증으로 인한 Eisenmenger 증후군 환자에서 시행된 심장-폐이식 수술에 대한 증례 보고이다. 동맥관 개존증으로 인한 Eisenmenger 증후군인 32세의 여자 수혜자는 1996년 6월 이후 심부전으로 심한 호흡곤란을 겪고 있었으며, 1997년 7월초에 빈맥, 호흡곤란, 하지부종을 주소로 응급실을 통하여 입원한 후 호흡곤란, 저산소증, 상심실성 빈맥, 전해질 이상 등으로 치료받으면서 퇴원하지 못하고 심장-폐 이식 대상자로 등록되었다. 수술전에 시행한 심초음파검사에서 우-좌단락의 동맥관개존증, 우심실 및 우심방의 심한 확장, 100 mmHg의 우심실 수축기압 소견을 보였다. 폐동맥압이 체동맥압보다 높게 역전되어 있었고 심한 이산화탄소 정체 및 저산소증의 소견을 보여서 중환자실에서 인공호흡기로 호흡기능을 보조받고 있었다. 공여자는 교통사고로 두부손상을 입고 뇌사판정을 받은 1 8세 남자였다. 공여자 및 수헤자의 혈액형은 모두 AB(+)형이었다. 1997년 10월 26일 심장-폐이식을 시행하였다. 심장 -폐분절은 공여자가 있던 타병원에서 구득하여 냉장보존 상태로 본원으로 이송하였다. 이식된 심장 및 폐의 총 허혈 시간은 각각 249분 및 270분이었다. 면역억제요법은 cyclosporine, azathioprine을 수술전부터 투여하였으며 steroid 는 기관 문합부위의 치유와 감염예방을 위하여 수술후 3주 이후부터 사용하였다. 환자는 수술후 31일째에 특별한 합 병증없이 퇴원하였으며 심장-폐이식후 4개월이 지난 현재, 심폐기능의 이상소견과 거부반응의 증거없이 NYHA funct ional class I의 상태로 지내고 있으며 면역억제제와 예방적 항생제, 소량의 이뇨제 및 항고혈압제를 복용하고 있다.