산업의학전문의 육성의 요구성

이승환,Lee, Seung-Hwan 대한산업보건협회 1993 산업보건 Vol.57 No.-

비행시차(jet lag)에 의한 여행객의 수면-각성 주기의 변화

이승환,김인,서광윤,Lee, Seung-Hwan,Kim, Leen,Sub, Kwang-Yoon 대한수면의학회 1995 수면·정신생리 Vol.2 No.2

Jet lag can be defined as the cumulative physiological and psychological effects of rapid air travel across multiple time zone. The consequences of jet lag include fatigue, general malaise, sleep disturbances, and reductions of cognitive and psychomotor performance, all of which have been documented in experimental biological and air crew personnel studies. Thus authors tried to study the jet lag of natural travellers by modified self reporting sleep log. Total 61 healthy travellers was studied for 3 days before and 7 days after jet-flights across seven to ten time zone. The eastbound travelling group was 38 persons, aged 19 -70 and westbound travelling group was 23 persons, aged 13 - 69. Sleep onset time, wake-up time, sleep latency, awakening frequency on night sleep, awakening duration on night sleep, sleepiness at wake-up and nap length were evaluated. Our results suggested that the 7 to 10 time zone shift gave significant influence to traveller's sleep-wake cycles. The date which subjective physical condition was recovered on was $5.16{\pm}1.50$ day after arrivals for eastbound, while for westbound, $4.91{\pm}1.62$ day. In eastbound travelling, sleep onset time became later than baselines and could not recover until 7th day. But in westbound, it became earlier than baseline and could recover until 6th day. The mean score of 24-hour sleepiness was greater in eastboumd than westbound. Therefore the eastbound travelling caused more sleep-wake cycle disturbance and daytime dysfunction than westbound travelling. In other parameters, there was no definite difference between east and westbound. From our results, it was suggested that the symptom severity of jet lag was dependent on the travelling direction. To demonstrate more definite evidence, large sized data collections and comparision by age difference were needed.

정신치료의 신경생물학적 기전

이승환,김승현,Lee, Seung-Hwan,Kim, Seung-Hyun 대한생물정신의학회 2002 생물정신의학 Vol.9 No.2

Polarisation of biological and psychosocial aspects of psychiatry is nowadays main stream. Current knowledges of the interaction between biology and psychology make it possible to consider a truly integrative approach of the two aspects. Research findings suggest that the neuronal plasticity is the key mechanism to answer how the mental function work to an environmental stimuli and how the psychotherapeutic approach work on the brain. Advances in neuroscience research have led to a more sophisticated understanding of how psychotherapy may affect brain function. Even though there have been a tremendous efforts to find out the neurobiological mechanism of mental function, the answer is at best premature. In this article, research findings about of neuronal plasticity, implicit memory, animal studies which were associated with psychotherapy and psychological aspects were reviewed.

연골 모세포종 - 골단과 견인골단의 비교 -

이승환,이모세,신규호,한수봉,Lee, Seung-Hwan,Lee, Mo-Ses,Shin, Kyoo-Ho,Hahn, Soo-Bong 대한근골격종양학회 2008 대한골관절종양학회지 Vol.14 No.1

목적: 연골 모세포종은 드문 원발성 양성 골종양으로 대부분이 장관골의 골단에 호발하는 것으로 알려져 있다. 본 연구에서는 19례의 환자를 대상으로 골단과 견인골단에 발생한 연골모세포종을 비교 분석하고자 하였다. 대상 및 방법: 1987년 8월부터 2005년 8월까지 연골모세포종으로 치료 받은 19례의 환자를 대상으로 하였으며 평균 추시기간은 5년이었다. 발생 연령은 평균 17.6세였으며 남자가 15명, 여자가 4명이었다. 수술적 치료로는 소파술, 소파술 및 골이식술, 소파술 및 시멘트 충전술을 시행하였다. 후향적 연구 방법을 통해 골단과 견인골단에 발생한 연골 모세포종에서 발생 연령, 증상의 기간, 종양의 크기, 성장판의 개폐여부, 병적골절여부, 재발여부 및 동맥류성 골낭종의 동반여부 등의 차이를 분석하였다. 결과: 발생부위는 골단이 11례, 견인골단이 8례였다. 골단에 발생한 경우는 대퇴골 원위부가, 견인골단은 대퇴골 대전자가 가장 많았다. 평균 발생 연령은 골단이 14.2세, 견인골단이 22.3세로 통계적으로 유의한 차이를 보였다. 골단에 발생한 11례중 3례에서는 성장판 유합후에 발생하였으며, 견인골단에서는 전례(100%)에서 유합후에 발생하여 통계적으로 유의한 차이가 있었다. 종양의 크기는 견인골단에 발생한 경우 통계적으로 유의하게 큰 것으로 나타났다. 결론: 연골 모세포종은 주로 장관골의 골단에 호발하는 것으로 알려져 있으나 20세 이상에서는 견인골단에서 주로 발생하여 진단에 주의를 요한다. 두 그룹간 발생 연령, 성장판의 개폐여부 및 종양의 크기가 통계적으로 유의한 차이가 있었으며 증상의 기간, 병적골절, 재발, 동맥류성 골낭종의 동반여부에는 차이가 없는 것으로 나타났다. Purpose: Chondroblastoma is a rare benign bone tumor which occurs most frequently at epiphysis of long bones. This study analyzed the difference between patients with chondroblastoma either on their epiphysis or apophysis. Materials and Methods: We reviewed 19 patients with chondroblastoma who visited our hospital from August 1987 to August 2005. The mean follow up period was five years. Fifteen patients were male and 4 patients were female. The mean age of the patients was 17.6 years. The treatment consisted of either curettage alone, curettage with bone graft or curettage with cementation. We retrospectively compared the difference between one chondroblastoma originating from the epiphysis and the other chondroblastoma originating from the apophysis in terms of age predilection, duration of symptoms, size of tumor, status of the physis, presence of pathologic fracture, recurrence rate and accompanying aneurismal bone cyst. Results: Among the 19 patients, 11 patients had chondroblastoma at the epiphysis, and 8 at the apophysis. Distal femur was the most common site for epiphysis lesions while the greater trochanter was the most common site for lesions arising at the apophysis. The mean age was 14.2 years in the epiphysis group and 22.3 years in the apophysis group. Chondroblastoma occurred after closure of the physis in 3 out of 11 cases in the epiphysis group and in all 8 cases in the apophysis group showing a statistical significance between the groups in terms of status of the physis at onset. Size of the lesion was bigger in the apophysis group with statistical significance. Conclusion: Chondroblastoma is known to occur frequently at the epiphysis of long bones, but our study shows that in patients over 20 years old it occurs more frequently at the apophysis which needs to be considered when making the proper diagnosis. There was a significant difference between the two groups in terms of the age of occurrence, status of physis and size of tumor while there was none in terms of the duration of symptoms, presence of pathologic fracture, recurrence rate and presence of accompanying aneurismal bone cyst.

표준논단 - 글로벌 시대의 국제표준 활용 방안

이승환,Lee, Seung-Hwan 기술표준원 2009 기술표준 Vol.91 No.-

MEMS 기술에 의한 초소형 마이크 로스피커

이승환,Lee Seung-Hwan 한국전기전자재료학회 2006 전기전자재료 Vol.19 No.8

국제표준화 활동 정책 제언

이승환,Lee, Seung-Hwan 기술표준원 2007 기술표준 Vol.62 No.-

전국노동위생단체연합회와의 교류회

이승환,Lee, Seung-Hwan 대한산업보건협회 1996 산업보건 Vol.99 No.-

NKN-(1-x)BNT-xBT 세라믹스의 압전 및 유전특성

이승환,남성필,이성갑,이영희,Lee, Seung-Hwan,Nam, Sung-Pill,Lee, Sung-Gap,Lee, Young-Hie 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.10

In this study, piezoelectric and dielectric properties of the $(Na_{0.5}K_{0.5})NbO_3-(1-x)(Bi_{0.5}Na_{0.5})TiO_3-xBaTiO_3$ [NKN-(1-x)BNT-xBT] ceramics were investigated. The lead-free NKN-(1-x)BNT-xBT ceramics were fabricated by a conventional mixed oxide method. The results indicate that the addition of $BaTiO_3$ significantly influences the sintering, microstructure, phase transition and electrical properties of NKN-BNT ceramics. A gradual change in the piezoelectric and dielectric properties was observed with the increase of BT contents. The dielectric constant, piezoelectric constant ($d_{33}$) and electromechanical coupling factor ($k_p$) increased at the morphotropic phase boundary (MPB). The $d_{33}$=184 pC/N, $k_p$=0.38, dielectric constant=1455 with dielectric loss value of less than 1% were obtained for the NKN-0.95BNT-0.05BT ceramics sintered at $1150^{\circ}C$ for 2h. These results demonstrate that the NKN-(1-x)BNT-xBT ceramics is an attractive candidate for lead-free piezoelectric materials.

후두 전적출술 후 기관루 재발에 대한 종격동 청소술 치험 1례

이승환,태경,유연희,최준석,Lee, Seung Hwan,Tae, Kyung,Yu, Yean-Hee,Choi, Joon-Suk 대한기관식도과학회 1999 大韓氣管食道科學會誌 Vol.5 No.1

Sternal recurrence has been defined as a diffuse infiltrate of neoplastic tissue at the junction of the amputated trachea and the skin. The overall prognosis is poor, resulting from progressive tracheostomal obstruction or massive hemorrhage due to erosion of major vessels. Neither radiation therapy nor chemotherapy has demonstrated any efficacy in controlling these sternal recurrence. Surgery, especially mediastinal dissection, may benefit only an occasional patient. Recently authors experienced one case of mediastinal dissection for sternal recurrence after total laryngectomy for laryngeal cancer. We report our case with a brief review of literature.