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일방향 응고법을 이용한 Mar M-247LC 초내열합금의 액상 물성 측정
김현철,이재현,서성문,김두현,조창용,Kim, Hyeon-Cheol,Lee, Jae-Hyeon,Seo, Seong-Mun,Kim, Du-Hyeon,Jo, Chang-Yong 한국재료학회 2001 한국재료학회지 Vol.11 No.9
Directional solidification experiments have been carried out at the solidification rates from 0.5 to 50$\mu\textrm{m}$/s in Mar M-247LC superalloy in which several important liquid properties were estimated by analyzing the interface stability and temperature gradient at the solid/liquid interface. The diffusion coefficient in the liquid was estimated by employing the constitutional supercooling criterion. The temperature gradients changed with solidification rates and latent heat of solidification. The thermal conductivities of solid and liquid could be estimated by heat flux balance at the solid liquid interface.
Anodic Bonding 에 의한 소자 열화에 관한 연구
김현철,전국진 ( Hyeon Cheol Kim,Kuk Jin Chun ) 한국센서학회 1993 센서학회지 Vol.2 No.2
Anodic Bonding technique is usually used for the fabrication of capacitive pressure sensor. This technique is that a Pyrex glass and a silicon wafer are heated and are applied by very high voltage, so surrounding electronic circuits are to be damaged. In this paper, we calculated the electric field intensity using the RC model for the anodic bonding and experimentally investigated the effects for MOS devices and operational amplifiers. The NMOS`s and PMOS`s within the 340㎛ and 380㎛ distance are so affected that their threshold voltages are changed for the case of anodic bonding at 300 ℃ and 800V. Also, the offset voltage was changed by 40mV, but DC gain and output swing were not changed for operational amplifier.
온도별 구리금파리(Lucilia sericata)의 발육
김현철,김수정,윤지은,조태호,최병렬,박정규,Kim, Hyeon-Cheol,Kim, Soo-Jung,Yun, Ji-Eun,Jo, Tae-Ho,Choi, Byeong-Reol,Park, Chung-Gyoo 한국응용곤충학회 2007 한국응용곤충학회지 Vol.46 No.1
Maggot therapy는 1900년대 초부터 압박성 욕창, 당뇨나 괴사에 의한 궤양, 수술 후 감염된 상처, 화상 등의 상처치료에 다시 사용되기 시작하였다. 환부에 처리할 적절한 발육단계의 무균유충을 생산하고, 증식 보존용 계통을 유지하는 데 필요한 자료를 얻기 위하여 온도별(15.4, 20.6, 22.5, 26.2, 29.1, $33.0^{\circ}C$) 발육실험을 수행하였다. 간배지(liver agar medium)에서 알기간과 1령 및 2령 기간은 $33.0^{\circ}C$에서 각각 9.0시간, 14.0시간, 18.6시간으로 가장 짧았다. 3령 기간과 번데기 기간은 $29.1^{\circ}C$에서 각각 285.0시간과 171.0시간으로 가장 짧았다. 온도별 발육기간을 기초로 각 발육단계의 발육영점온도와 유효적산온도를 산출하였다. 암수 성충은 대개 1개월 이상 생존하였고, 암컷은 일평생 2.7회 산란하였으며, 총 338.5개의 알을 낳았다. Maggot therapy (MT) has been re-introduced for non-healing wounds such as pressure sore, diabetic and necrotic ulcers, as well as infected surgical wounds, burn, and trauma injuries since early 1990s. For the production of sterile maggot of proper developmental stage, Lucilia sericata were studied on developmental periods of immature stages on liver agar medium under six different temperatures such as 15.4, 20.6, 22.5, 26.2, 29.1, and $33.0^{\circ}C$, and adult longevity and egg Production under $29^{\circ}C$. The periods of eggs and larvae of the 1st and the 2nd instars were shortest at $33^{\circ}C$ by 9.0, 14.0 and 18.6 hours, respectively. The periods of the 3rd instar larvae and pupae were shortest at $29.1^{\circ}C$ by 285.0 and 171.0 hours, respectively. Developmental zero point and total effective temperature far the development of each stage were calculated based on the developmental periods. Adults of both female and male lived more than one month. Females laid an average of 338.5 eggs through 2.7 times of egg laying throughout her lifetime.
악관절잡음 및 동통을 동반한 정복성 관절원판 변위환자에 대한 관절강 Pumping 효과
김현철,최종훈,박혜숙,김종열,Kim, Hyeon-Cheol,Choi, Jong-Hoon,Park, Hye-Suk,Kim, Chong-Youl 대한안면통증구강내과학회 1999 Journal of Oral Medicine and Pain Vol.24 No.1
Pumping into the upper joint cavity of the TMJ was done on patients who had reducible disc displacement with pain. This article discusses the change in TMJ sounds before and after the Pumping treatment. 20subjects(mean age of $32.1{\pm}10.2yr$)were selected among those who visited the department of Oral Medicine of Yonsei University for the treatment of craniomandibular dysfunctions. Through a thorough history taking, clinical exam and X-ray taking these subjects were diagnosed as reducible disc displacement patients, and they were subdivided into two groups as acute and chronic according to the time the TMJ sound was made. Sonopak was used to measure the TMJ sound before, right after and one-week after the Pumping treatment. VAS was used to measure the degree of subjective TMJ complaints(sounds and pain) before and one-week after the Pumping treatment. Vibration related items included total integral, high integral, low integral, ratio of high integral to low integral, peak amplitude, peak frequency and median frquency. 1. It was not statistically significant between the acute and chronic groups before the treatment. However, total integral, high integral, low integral, peak amplitude, peak frequency, median frequency showed to be greater in the chronic group. 2. In all the subjects, just after the Pumping treatment was done, total integral, high and low integral, peak amplitude and peak frequency significantly decreased (p<0.05). Even after one week, low integral, peak frequency and median frequency significantly decreased (p<0,05), and the TMJ sound diminished accordingly. 3. Comparing the two groups(before and right after the Pumping treatment), there was the following difference ; in the acute group, high integral, high amplitude, high frequency and median frequency significantly decreased(p<0.05). In the chronic group, total integral, high integral, low integral, ratio, peak amplitude and peak frequency significantly decreased(p<0,05). It was not statistically significant between the acute and chronic group. 4. Comparing the two groups(right after and one week after the Pumping treatment), there was the following difference : in the acute group, high integral, high amplitude, high frequency and median frequency significantly decreased(p<0.05), In the chronic group, low integral significantly decreased(p<0.05). However, although it was not statistically significant, after one week, there was an increase in total integral, ratio, peak amplitude and peak frequency compared to right after the treatment group. 5. In the VAS of before and one week after the Pumping treatment of the TMJ pain and sound, the TMJ pain significantly decreased(p<0.05) in both the acute and chronic group. However, it was not statistically significant between the two groups. There was a statistically significant decrease(p<0.05) in the TMJ sound in the acute group after one week of Pumping treatment, but no change was notable in the chronic group and it was not statistically significant between the two groups. From the above results, we can conclude that Pumping into the upper joint cavity of patients having reducible disc displacement is effective in reducing clicking and pain. Therefore, it can be applied in diverse clinical fields.
과학기술 동호인소개-전국학교컴퓨터 교육연구회(NASEC)
김현철,Kim, Hyeon-Cheol 한국과학기술단체총연합회 1995 과학과 기술 Vol.28 No.11
컴퓨터 교육의 이론과 실제에 관한연구를 통해 학교사회의 정보화 촉진에 기여할 목적으로 91년창립된 전국학교컴퓨터 교육연구회는 3천여명의 회원이 전국12개 시 도지회를 중심으로 8회의 컴퓨터교육과 6회의 학술세미나를 개최하는 등 왕성한 활동을 펴오고 있다.