• Nuclear Engineering and Technology
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• 제50권6호
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• pp.907-914
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• 2018

In this article, we conducted molecular dynamics simulations to investigate the effect of applied strain and temperature on irradiation-induced damage in alpha-zirconium. Cascade simulations were performed with primary knock-on atom energies ranging between 1 and 20 KeV, hydrostatic and uniaxial strain values ranging from -2% (compression) to 2% (tensile), and temperatures ranging from 100 to 1000 K. Results demonstrated that the number of defects increased when the displacement cascade proceeded under tensile uniaxial hydrostatic strain. In contrast, compressive strain states tended to decrease the defect production rate as compared with the reference no-strain condition. The proportions of vacancy and interstitial clustering increased by approximately 45% and 55% and 25% and 32% for 2% hydrostatic and uniaxial strain systems, respectively, as compared with the unstrained system, whereas both strain fields resulted in a 15-30% decrease in vacancy and interstitial clustering under compressive conditions. Tensile strains, specifically hydrostatic strain, tended to produce larger sized vacancy and interstitial clusters, whereas compressive strain systems did not significantly affect the size of defect clusters as compared with the reference no-strain condition. The influence of the strain system on radiation damage became more significant at lower temperatures because of less annealing than in higher temperature systems.

• 대한금속재료학회지
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• 제49권7호
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• pp.577-582
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• 2011

The newly developed ${\alpha}-case$ controlled mold material for Ti investment castings was suggested in this research. The $Al_2O_3$ mold containing interstitial $TiO_2$ and substitutional $Ti_3Al$ was manufactured by the reaction between $Al_2O_3$ and Ti. It is obvious that as the $TiO_2$ and $Ti_3Al$ content in the mold surface were increased, the depth of the interfacial reaction was significantly reduced. In addition, substitutional $Ti_5Si_3$ in the mold surface owing to the reaction between Ti and $SiO_2$ from the binder was effective for ${\alpha}-case$ reduction. Therefore, the ${\alpha}-case$ reduction was accomplished by the diffusion barrier effect of interstitial $TiO_2$, substitutional $Ti_3Al$ and $Ti_5Si_3$.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2879-2888
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• 2023

In fusion environments, large scales of helium (He) atoms are produced by a radical transformation along with structural damage in structural materials, resulting in material swelling and degradation of physical properties. To understand its irradiation effects, this paper investigates the stability, electronic structure, energetics, charge density distribution, PDOS and TDOS, and diffusion processes of He impurities in 6HSiC materials. The formation energy indicates that a stable, favorable position for interstitial He is the HR site with the lowest energy of 2.40 eV. In terms of vacancy, the He atom initially prefers to substitute at pre-existing Si vacancy than C vacancy due to lower substitution energy. The minimum energy paths (MEPs) with migration energy barriers are also calculated for He impurity by interstitial and vacancy-mediated diffusion. Based on its calculated energy barriers, the most possible diffusion path includes the exchange of interstitial and vacancy sites with effective migration energies ranging from 0.101 eV to 1.0 eV. Our calculation provides a better understanding of the stabilization and diffusion behaviors of He impurities in 6H-SiC materials.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1480-1489
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• 2024

Displacement cascade behaviors of Ti-6Al-4V alloys are investigated using molecular dynamics (MD) simulation. The embedded atom method (EAM) potential including Ti, Al and V elements is modified by adding Ziegler-Biersack-Littmark (ZBL) potential to describe the short-range interaction among different atoms. The time evolution of displacement cascades at the atomic scale is quantitatively evaluated with the energy of primary knock-on atom (PKA) ranging from 0.5 keV to 15 keV, and that for pure Ti is also computed as a comparison. The effects of temperature and incident direction of PKA are studied in detail. The results show that the temperature reduces the number of surviving Frenkel pairs (FPs), and the incident direction of PKA shows little correlation with them. Furthermore, the increasing temperature promotes the point defects to form clusters but reduces the number of defects due to the accelerated recombination of vacancies and interstitial atoms at relatively high temperature. The cluster fractions of interstitials and vacancies both increase with the PKA energy, whereas the increase of interstitial cluster is slightly larger due to their higher mobility. Compared to pure Ti, the presence of Al and V is beneficial to the formation of interstitial clusters and indirectly hinders the production of vacancy clusters.

• Tuberculosis and Respiratory Diseases
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• 제87권1호
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• pp.40-51
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• 2024

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrosing interstitial pneumonia with a very poor prognosis. Accurate diagnosis of IPF is essential for good outcomes but remains a major medical challenge due to variability in clinical presentation and the shortcomings of existing diagnostic tests. Medical history collection is the first and most important step in the IPF diagnosis process; the clinical probability of IPF is high if the suspected patient is 60 years or older, male, and has a history of cigarette smoking. Systemic assessment for connective tissue disease is essential in the initial evaluation of patients with suspected IPF to identify potential causes of interstitial lung disease (ILD). Radiologic examination using high-resolution computed tomography plays a pivotal role in the evaluation of patients with ILD, and prone and expiratory computed tomography images can be considered. If additional tests such as surgical lung biopsy or transbronchial lung cryobiopsy are needed, transbronchial lung cryobiopsy should be considered as an alternative to surgical lung biopsy in medical centers with experience performing this procedure. Diagnosis through multidisciplinary discussion (MDD) is strongly recommended as MDD has become the cornerstone for diagnosis of IPF, and the scope of MDD has expanded to monitoring of disease progression and suggestion of appropriate treatment options.

• Tuberculosis and Respiratory Diseases
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• 제61권3호
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• pp.294-298
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• 2006

단순 흉부 X-선에서 양측성 폐문 림프절 비후를 보이는 대표적인 질환으로 유육종증, 림프종, 결핵, 폐암, 아밀로이드증, 브루셀라증, 콕시디오이데스진균증(Coccidioidomycosis) 등이 있다. LIP의 방사선학적 소견은 보통 비특징적이고, 초기 병변에서 양측 폐하에 망상, 망상결절성 침윤을 보이며 병이 진행됨에 따라 낭성 변화를 동반하고, 봉소상을 보이는 경우가 있으나, 본 증례의 환자와 같이 종격동과 양측 폐문에 림프절 종대를 동반하는 경우에 대한 보고는 흔치 않다. 저자들은 흉부 X-선 및 CT상 종격동과 양측 폐문부의 림프절 종대를 동반한 간질성 결절성 폐침윤 소견을 나타낸 환자에서 흉강경하 폐 생검을 통해 진단된 LIP를 경험하였기에 문헌고찰과 함께 보고하는 바이다.

• Journal of Periodontal and Implant Science
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• 제33권4호
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• pp.693-703
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• 2003

The present study evaluated the effects of guided tissue regeneration using xenograft material(deproteinated bovine bone powder), with and without Calcium sulfate membrane in beagle dogs. Contralateral fenestration defects (6 ${\times}$ 4 mm) were created 4 mm apical to the buccal alveolar crest of maxillary premolar teeth in 5 beagle dogs. Deproteinated bovine bone powders were implanted into fenestration defect and one randomly covered Calcium sulfate membrane (experimental group). Calcium sulfate membrane was used to provide GTR. Tissue blocks including defects with soft tissues which were harvested following four & eight weeks healing interval, prepared for histo-phathologic analysis. The results of this study were as follows, 1. In control group, at 4 weeks after surgery, new bony trabecular contacted with interstitial tissue and osteocytes lie cell were arranged in new bony trabecule. Bony lamellation was not observed. 2. In control group , at 8 weeks after surgery, scar-like interstitial tissue was filled defect and bony trabecule form lamellation. New bony trabecular was contacted with interstitial tissue but defect was not filled yet. 3. In experimental group, at 4 weeks after surgery, new bony trabecular partially recovered around damaged bone. But new bony trabecule was observed as irregularity and lower density. 4. In experimental group, at 8 weeks after surgery, lamella bone trabecular developed around bone cavity and damaged tissue was replaced with dense interstitial tissue. In conclusion, new bone formation regenerated more in experimental than control groups and there was seen observe more regular bony trabecular in experimental than control groups at 4 weeks after surgery. In control group, at 8 weeks after surgery, the defects was filled with scar-like interstitial tissue but, in experimental group, the defects was connected with new bone. Therefore xenograft material had osteoconduction but could not fill the defects. We thought that the effective regeneration of periodontal tissue, could be achieved using GTR with Calcium sulfate membrane.

• 한국가금학회지
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• 제37권3호
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• pp.247-253
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• 2010

텔로미어(telomere)는 염색체 양 말단에 위치하는 DNA와 단백질의 복합체로서 (TTAGGG)n의 단순 반복 염기 서열로 이루어져 있다. 그러나 일부 조류 및 척추동물의 경우 염색체의 양 말단 부위외 간질적 위치에도 telomeric DNA sequence가 분포한다. 본 연구는 닭 염색체에 있어 telomeric DNA의 분포 양상을 제시하고자 한국 재래닭의 초기 배아로부터 염색체 표본을 제작하고, telomeric DNA probe를 이용한 FISH를 수행하여 염색체 상 텔로미어의 분포 양상을 분석하였다. 분석 결과, 닭의 모든 염색체 양 말단부에 텔로미어가 분포하는 것으로 나타났으며, 더불어 대형 염색체 중 1번의 1q32, 1p11, 1p23 위치와 2번 염색체의 2q24 및 3번 염색체 3q32에 interstitial telomeric signal(ITS)이 존재하는 것이 확인되었다. 이러한 한국 재래닭 염색체의 텔로미어 분포 양상은 이전 Gallus domesticus에서 발표한 분포 양상과 거의 일치한 것으로 나타났다. 한국 재래닭의 각 염색체별 텔로미어 함유율은 4.6~16.3% 정도로 분석되었으며, 거의 대부분의 염색체에서 단완 말단부의 telomeric DNA의 함량이 장완 말단부보다 높은 것으로 나타났다. 닭 염색체에서 ITS의 존재와 분포 양상은 핵형학적으로 진화 과정 중 염색체 간의 융합에 의해 신생 염색체가 형성되었을 가능성을 시사한다.

• Journal of Chest Surgery
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• 제39권5호
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• pp.382-386
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• 2006

배경: 다양한 형태의 간질성 폐질환의 확진을 위해서 조직학적인 진단을 필요로 한다. 흉부외과의 폐생검이 간질성 폐질환의 진단에 얼마나 도움이 되는지 알아보고자 하였다. 대상 및 방법: 1995년 6월부터 2002년 11월까지 경상대학교병원 흉부외과에서 폐생검을 시행한 17명의 환자를 대상으로 병록지, 전화설문을 시행하여 후향적인 조사를 하였다. 결과: 평균 나이는 $49{\pm}22$세였다. 나이의 범위는 1세에서 70세였다. 주소는 대부분 호흡곤란이었으며, 간질성 폐질환의 확진을 위하여 소아과와 내과에서 의뢰된 환자들이었다. 폐생검 접근방법은 흉강경 6예, 개흉술 11예였다. 11예에서(65%) 확진이 가능하였고, 조직학적인 진단이 확인된 후 13예에서(76%) 치료방법을 변경하였다. 결론: 외과적인 폐생검술은 간질성 폐질환의 감별진단에 도움을 줄 수 있다. 폐생검술은 수술 중 사망이 없을 정도로 안전한 방법이다. 진단이 되지 않은 간질성 폐질환의 감별진단을 위하여 폐생검이 권유하는 것은 치료방법의 결정에 중요하다.

• Journal of Chest Surgery
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• 제29권10호
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• pp.1133-1137
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• 1996

흉강경을 이용한 흉부수술의 경우 최근 들어 상당한 발전이 계속되면서 시술할 수 있는 분야가 크게 증가하였다. 중앙대학교 흉부외과에서는 1994년 9월부터 1995년 8월까지 비디오흉강경을 이용한 수술 67례의 임상결과를 보고하는 바이다. 1. 진단은 기흉 35례, 미만성 간질성 폐질환 9례, 농흉 7례, 폐암에 의한 삼출액 3례, 다한증 3례, 흉강내 이물질 2례, 중피종 1례, 속립성 폐결핵 1례, 기질화된 폐렴 1례였다 2. 수술은 기흉환자 35례중 흉막 유착이 심하여 개흉술로 전환한 2례를 제외한 33례 에서 비디오 흉강경 기포절제술을 시행하였다. 그외에 흉강경을 이용한 지혈 5례, 세척술 7례, 이물질 제거 2례, 악성 늑막 삼출시 활석분무 3례, 교감신경 절제 술을 3례 시행하였다. 흉강경적 생검은 12례 시행하였다. 3. 기흉환자중 재발성 기흉으로 18례 수술하였고 지속적 공기누출 12례, 단순흉부사진상 기포가 보인 례가 5례 있었다. 심한 유착을 보여 흉강경에서 전환한 개흉적 기포제거술 2례를 시행하였다. 4. 비디오흉강경적 생검을시행한 12례의 병리학적 소견은 특발성 폐섬유화증 9례, 속립성 결핵 1례, 중피종 1례 및 기질화된 폐염 1례였다. \ulcorner鈒\ulcorner폐섬유화증 9례중 7례는 박리성 간질성 폐염, 2례는 통상 성 간질성 폐염이었다. 5. 비디오흉강경 67례중에서 63례에서 특별한 합병증 없이 퇴원하였고 4례에서 합병증이 발생하였다. 2 례가 계속된 공기누출, 2례는 반대측의 무기폐가 발생하였다. 따라서 비디오홍강경 수술은 비교적 안전하고 합병증이 적으며 앞으로 흉부수술영역에서 사용범위가 확대될 것으로 생각된다.