IN 738LC 합금의 미세조직 열화와 물성의 상관성 연구

유정훈,주성욱,신기삼,허성강,이재현,김의현,정진성,장성호,송기욱,하정수,Yoo Junghoon,Jo Sungwook,Shin Keesam,Hur Sungkang,Lee Je-Hyun,Kim Eui-Hyun,Jung Jine-sung,Chang Sungho,Song Geewook,Ha Jeongsoo 한국재료학회 2004 한국재료학회지 Vol.14 No.1

IN 738LC, the major material for gas-turbine for power generation, was heat treated at $750^{\circ}C$, $850^{\circ}C$, $950^{\circ}C$ for 1000, 2000, and 4000 hrs and the microstructural evolution and mechanical properties were examined using optical microscope, XRD, SEM/EDS. The results showed ${\gamma}$', the main strengthening elements in this alloy, was about 300 nm in size and was about 56% by area fraction in as-cast samples. The area fraction of ${\gamma}$' peaked at 2000 hours at $750^{\circ}C$. The average diameter of the ${\gamma}$' which was about 300 nm at ascast specimen increased to about 1 $\mu\textrm{m}$ after heat treatment at $950^{\circ}C$ for 4000 hrs. Carbides were formed at dendrite, cell or grain boundaries which was ascribed to the segregation caused by solute redistribution during solidification. It was found that MC type carbides formed at low temperature, whereas carbides of $M_{23}$ /$C_{ 6}$/ type formed at higher temperature or at longer degradation. The hardness and impact energy decreased as the heat treatment temperature or time of retention increased, which was inaccrodance with the area fraction of ${\gamma}$'.

식도 평활근종의 임상적 고찰

유정훈 대한흉부심장혈관외과학회 1991 Journal of Chest Surgery Vol.24 No.5

The five patients with leiomyoma of esophagus were treated from 1976, to 1990. The patients were 4 men and 1 woman whose ages ranged from 28 to 53 years. One of them was asymptomatic, two had mainly dysphagia and the others complained indigestion and epigastric discomfort. There was no relationship between the severity of symptoms and the size of tumor. The preoperative diagnosis was made by esophagoscopy and esophagogram, and all of them were treated by thoracotomy and enucleation. There was no postoperative complication and the results were excellent.

기관및 기관지 협착증 환자의 외과적 치료

유정훈 대한흉부심장혈관외과학회 1992 Journal of Chest Surgery Vol.25 No.11

We experienced 5 cases of tracheal stenosis and 7 cases bronchial stenosis treated surgically at the Department of Thoracic and Cardiovascular Surgery, School of Medicine, Hanyang University during 5 years. The causes of tracheal stenosis were prolonged endotracheal intubation 1 case, tracheostomy 1 case, the sequela of endobronchial tuberculosis 2 cases and tracheomalacia 1 case. The causes of bronchial stenosis were all endobronchial tuberculosis. The managements of tracheal stenosis were tracheal resection and end to end anastomosis. The resected lengths of trachea were 1.5cm, 3cm and 7.5cm. One case of suglottic stenosis was underwent the resection of trachea, 8cm in length, and the laryngotracheal anastomosis was done, but the re-stenosis of trachea was developed after 4 weeks post-operatively. One case of tracheomalacia was done permanent tracheostomy only, because the entire trachea was adhered to the surrounding tissue. The managements of bronchial stenosis were resection of involved lobe or one lung, in the 5 case. One case with Lt. main bronchial stenosis and atelectasis of Lt. upper lobe was done the lobectomy of Lt. upper lobe only and then, the Lt. pneumonectomy was done re-operatively because the atelectasis of Lt. lower lobe had continued. The other one case with stenosis of Rt. main bronchus, failed the insertion of metalic stent, was underwent the Rt. upper lobe lobectomy, sleeve resection and side to end anastomosis

주기관 긴 협착증 환자의 수술 치험

유정훈 대한흉부심장혈관외과학회 1992 Journal of Chest Surgery Vol.25 No.6

Recently we have experienced one case of long tracheal stenosis which developed after pulmonary tuberculosis. The patient was 32 years old woman, 165cm in height. She complained severe dyspnea and headache. We could hear the inspiratory wheezing sound and stridor without stethoscope. Preoperative tracheogram and chest CT scan showed long tracheal stenosis from the posterior portion of clavicular head to the upper portion of carina and right main bronchus. Under the general anesthesia, the stenotic segment, about 7.5cm, was resected and end to and anastomosis was performed successfully through the right anterolateral thoracotomy and supraclavicular collar incision. Her postoperative course was uneventful and the patient has remained well till now.

High-Tc superconductivity from an atomic point of view via tunneling

유정훈,이진호 한국물리학회 2017 Current Applied Physics Vol.17 No.6

Even after 30 years of discovery of the high temperature superconductivity (HTSC) from the cuprate compounds by Bednorz and Müller, the mechanism of the formation of Cooper pairs well above the liquid nitrogen boiling temperature is still remained to be elucidated. The discovery of a yet another HTSC family of the iron-based superconductors seemed to add more complexity to this puzzle, but also seems to render a prospect of finding a universal principle shared by the entire HTSC family. The tunneling experiments, on the other hand, also witnessed remarkable breakthroughs ever since Giaever succeeded the first tunneling experiment on a superconducting aluminum. The scanning tunneling microscopy (STM) invented by Binnig and Rohrer began to be heavily applied to the research of the condensed matter and became one of the most versatile spectroscopic tools as well as the most powerful microscope available also in the HTSC research field as of today. In this review, we would like to convey a snapshot of the current application of the STM in the research of HTSC, mainly focusing on the studies using the spectroscopic imaging scanning tunneling microscopy (SI-STM) which eventually led to the scanning Josephson tunneling microscopy (SJTM) by which we can visualize the superconducting Cooper pairs in an atomic scale.

전쟁과 과학 (1) - 원자탄과 운반 체계

유정훈 한국소음진동공학회 2010 소음 진동 Vol.20 No.1

흉부외과 질환의 진단시 FNAB 의 유용성과 객담세포검사 및 기관지 내시경 검사와의 비교 고찰

유정훈 대한흉부심장혈관외과학회 1990 Journal of Chest Surgery (J Chest Surg) Vol.23 No.6

From March 1986 to June 1990, the percutaneous Fine Needle Aspiration Biopsy[FNAB] of 102 thoracic lesions were performed with Westcott needle [slotted 20G or 22G thin needle], for the purpose of identifying and diagnosing thoracic lesions. There were 94 lung lesions [67 malignant tumors, 27 benign lesions] and 8 mediastinal and chest wall lesions. The results of FNAB were compared with sputum cytology and bronchoscopic examinations. The sputum cytologic examinations were performed in 54 cases of malignant lung tumor and the malignant cell was found at the 18 cases [33%]. We bronchoscopic examinations were performed in 24 cases and the malignant cell was found at the 12 cases [55%]. The positive diagnostic rate of malignancy was 100% by FNAB. Among them, 55 cases [82%] were diagnosed by cytologic examinations and 43 cases[64%] by both. The specific diagnoses for benign lung lesions in 15 cases[55%] and for mediastinal and chest well lesions in 5 cases[62%]. The 7 patients[6.9%] developed the pneumothorax and 5 of them required the treatment. Therefore, the FNAB of thoracic lesions may be a preferred diagnostic method because of its safety, simplicity and accuracy.

현물기본소득 관점에서 바라본 지역 간 대중교통서비스 제공

유정훈,이인규,최정윤 한국교통연구원 2016 交通硏究 Vol.23 No.2

In recent years, basic income related policies have risen as social and political issues attracting interests from all socioeconomic classes of people. Provision of a minimum level of public transport service to the public under market price can be considered a form of basic income in-kind paid by the central government. In this study, a minimum level of intercity public transport service is analyzed using in-depth information on intercity transit routes and operational attributes. The analysis of connectivity and competitiveness of intercity transit shows domestic inequality of intercity transit service has become severe. In particular, cities with a higher population and GRDP have better connectivity and competitiveness and, at the same time, have more transit stops for high-speed rail and express bus services, which provide a higher level of intercity transit service. In order to reduce the gap in public transit services, it is necessary to establish standards and methodologies to create a minimum level of intercity public transport. This study is expected to be utilized as a starting point in this regard. 최근 국내에서는 기본소득과 관련된 정책이 사회정치적 이슈로 부각되고 있으며, 이에 대한 사회 전 계층의 관심이 증가하고 있다. 국가에서 모든 시민들에게 시장 가격 이하로 기초적인 대중교통서비스를 공급하는 것은 일종의 현물기본소득을 제공하는 것과 같다고 볼 수 있다. 본 연구에서는 전국 지역 간 대중교통의 경로정보, 운행정보 등을 활용하여 최소 대중교통 공급 수준을 분석하였다. 전국 지역 간 대중교통의 연결성 및 경쟁력을 분석한 결과, 대중교통 공급에 있어 지역 간 불균형이 심각한 상황임을 확인할 수 있었다. 특히, 인구와 지역 내 총생산이 높고 고급 대중교통 서비스를 대표하는 고속철도와 고속버스의 정차횟수가 많은 지역일수록 대중교통 연결성 및 경쟁력이 높은 것으로 나타났다. 이러한 기초 대중교통 공급격차를 해소하기 위해서는 최소 대중교통서비스 수준을 정의할 수 있는 방법과 기준이 개발되어야 하며, 본 연구가 이에 대한 중요한 출발점으로 활용될 것으로 기대된다.

배출가스 중 SO₂ 농도에 따른 응축성 먼지의 발생특성

유정훈,임슬기,이도영,유명상,김종호 한국대기환경학회 2017 한국대기환경학회 학술대회논문집 Vol.2017 No.11

LNG 연소시설의 먼지 배출계수 산정

유정훈,송지한,황인준,이도영,김종호 한국대기환경학회 2020 한국대기환경학회 학술대회논문집 Vol.2020 No.10