중증근무력증 환자의 말초 혈액내 T 림프구 분획의 변화

최철희,최인홍,김우경,선우일남,최철희 대한신경과학회 1998 대한신경과학회지 Vol.16 No.1

[논평] 장훈태 교수, 이만석 선교사의 발표에 대한 논평

최철희 기독교학술원 2015 영성포럼 Vol.24 No.1

Ciprofloxacin 제제의 생물학적 동등성에 관한 연구

최철희,신재국,신완균,유호진,이경훈,정원석,장인진,신상구 대한화학요법학회 1991 대한화학요법학회지 Vol.9 No.1

국내 시판중인 ciprofloxacin 제제인 Citopcin®(250㎎ tablet)의 동등성을 검토하기 위해 제조원인 Bayer사의 Citopcin®(250㎎ tablet)를 기준제제로 하여 18명의 건강한 남성 피험자를 대상으로 500㎎ 1회 교차 경구 투여후 약동학적 성상을 분석비교한 결과는 다음과 같다. 시험제제의 생체 이용율의 지표인 AUC, C_(mao), T_(max) 및 MRT들의 평균치는 백분율차이에 있어 모든 기준제제 지표의 ± 20% 이내였으며, 이들 생체 이용율 지표들은 분산분석 검정에서 차이를 인지할 수 없었다.생체 이용율 지표들의 기준제제에 대한 백분율 90% 대칭 신뢰구간 검토시 모든 경수들에서 ± 20% 이내의 조건을 만족하였으며 AUC의 경우에는 대칭형 신뢰구간으로 변환시 95% 신뢰구간에서도 동등성의 조건을 만족하였다, 이상의 시험결과로 시험제제인 Citopcin®은 기준제제인 Ciprobay®와 생물학적 동등한 제제로 판단되었다. The pharmacokinetics of ciprofloxacin was studied for the evaluation of the bioequivalence of the generic ciproflocacin products. Two single doses of 500㎎ each of ciprofloxacin(Ciprobay® 250㎎ tablet as a reference compound and Citopcin® 250㎎ tablet s a test compound) were administered orally to ighteen male volunteers in a balanced, randomized crossover design. Pek plasma levels of ciprofloxacin were observed about 1 hour after the doses and the peak concentrations of both products were similar(Ciprobay®, 3.18㎍/㎖; Citopcin®, 2.89㎍/㎖). The values of other pharmacokinetic parameter of ciprofloxacin computed for Ciprobay® are presented in that order: AUC=13.53:12.47㎍·h/㎖, T_(max)=1.28:1.14 hours; MRT=5.30:5.08 hours; t_(1/2)β=3.65:3.47 hours. No satistically significant, differences were detected when AUC and the other parameters were compared with the method of ANOVA. Using the criteria of 90% confidence interval for the assessment of bioequivalence al the parameters were acceptable. The products were found to be equivalent on the premise that no significant difference was detected when the relevant pharmacokinetic parameters were compared, and the confidence limit analysis showed acceptable results.

GBAS 지상시스템 시범공항 구축을 위한 설계

최철희,김성욱,김서원,김동민,전향식 한국항공우주학회 2012 한국항공우주학회 학술발표회 논문집 Vol.2012 No.11

GBAS 지상시스템은 시범공항인 김포공항을 대상으로 CAT-I 장비를 설치하여 운용하기 위해 설치후보지 조사와 평가를 위한 데이터를 수집하고 주변 환경에 대한 분석을 한다. 이를 토대로 설치후보지를 선정하고, 시스템의 성능을 고려하여 주변 환경과 장치와의 간섭을 최소화 하도록 설치한다. 본 논문에서는 활주로 필드사이트에 기준국수신기(Reference Receiver) 4대, VDB 송신 안테나 1대, 쉘터(Shelter) 1대의 설계결과를 분석한다. 기준국수신기는 위성 신호를 수신하여 쉘터의 GBAS 장비로 데이터를 전송하여 처리한다. 처리된 보정 신호는 VDB 송신 안테나를 통해 항공기의 수신 장치로 전송한다. 장치 운용을 위한 전원 및 통신을 구축과 관로의 요구사항을 분석하여 반영한다. GBAS ground system collects data for the proposed site investigation and evaluation and analyze about the surrounding environment in order to set up and use CAT-Ⅰ equipment in the Gimpo airport. The installation proposed site is selected based on this, It sets up in order to minimize the interference with the system and surrounding environment. In this paper, we analyze at the runway field site about the design result one GBAS equipment in four Reference Receivers, one VDB transmitter antenna, and shelter. In Reference Receiver, the complete system receives the satellite signal and it transmits and processes data with GBAS equipment of the shelter. The processed correction signal transmits to the receiving device of the airplane through VDB. The power and communication is built for the equipment operation and the requirement of the conduit line is analyze reflected.

파킨슨병 환자의 음성강도 및 청성유발반응 특성

최철희,박채림,최성희 한국언어청각임상학회 2019 Communication Sciences and Disorders Vol.24 No.4

배경 및 목적: 파킨슨병은 감각과 운동의 통합능력 저하로 야기되는 만성 퇴행성 질환으로 자신의 음성강도를 조절하는데 어려움을겪는 감각장애이다. 본 연구는 파킨슨병이 청각의 말초와 중추신경계에 미치는 영향 및 음성강도와 청성유발반응의 관계를 살펴보고자 한다. 방법: 총 24명(파킨슨병 환자군 12명과 정상대조군 12명)을 대상으로 순음청력검사 및 청성유발반응 검사를 실시하였으며 소음계를 사용하여 모음 /ㅏ/ 연장 발성과 표준 문단 ‘가을’ 문장 읽기 시 음성강도를 측정하였다. 청력검사는 순음청력검사기를 사용하여250에서 8,000 Hz의주파수영역에서청력역치를측정하였으며, 청성유발반응은청성뇌간반응, 청성중기반응및청성후기반응을측정하였다. 결과: 순음청력결과, 파킨슨병 환자군의 청력역치는 정상대조군보다 유의미한 차이를 보이지 않았다. 음성강도는 파킨슨병 환자군의 평균 음성강도가 정상대조군에 비해 유의미하게 낮았다(p<.05). 한편, 파킨슨병 환자군의 청성중기반응의 Na, Pa, Nb의 잠복기는 정상군보다 유의미하게 지연되었다. 또한, 파킨슨병 환자군의 Na-Pa의 파간 진폭이 유의미하게 낮았다. 청성후기반응은 파킨슨병환자군과 정상군 간 유의한 차이를 보이지 않았다. 파킨슨병 환자의 음성강도는 청성뇌간반응 Wave III의 잠복기와 유의미한 상관관계를 보였으며, 파킨슨병의 환자의 음성 강도가 작을수록 Wave III의 잠복기도 지연되었다. 논의 및 결론: 전기생리학적 검사는 파킨슨병환자의 감각기능이상과 관련된 임상적으로 유용한 정보를 제공해 주었으며, 파킨슨병 환자군의 낮은 음성강도는 말초청각기능의 문제이상이아닌중추청각기능과관련이있으며, 감각조절의기능문제로발생함을시사한다.

파킨슨 병에서 levodopa치료가 우울증에 미치는 영향

최철희,이준홍,손영호,김진수 대한신경과학회 1997 대한신경과학회지 Vol.15 No.4

위성 변조 비콘 신호의 2위상 특성을 이용한 주파수 오프셋 보상방법에 대한 연구

최철희,Choi, Chul-Hee 한국인터넷방송통신학회 2018 한국인터넷방송통신학회 논문지 Vol.18 No.1

위성 변조 비콘 신호는 위성에서 생성한 TOD (Time of Day) 데이터를 gold sequence를 이용하여 확산 시킨 후 linear phase modulation을 통해 전송된다. 변조 비콘 신호를 수신 시 위성과 지상 수신기 간 특성 차이 때문에 주파수 오프셋(FO)이 발생한다. 기존 위성 변조 비콘 수신기는 변조 비콘 신호를 FFT(Fast Fourier Transform)를 이용하여 주파수를 동기화시키는 방법이며, 이는 시스템 구현 관점에서 딜레이 및 복잡도를 증가 시킬 뿐만 아니라 points 간 생기는 FO과 phase offset에 의한 위상차를 보정하는 별도의 회로가 필요하다. 본 논문에서는 이를 극복하기 위해 변조 비콘 신호의 2위상 성형된 특성을 이용하여 coarse FO와 phase offset을 한 번에 보정 및 복조하기 위한 방안과 그에 따른 하드웨어 구성도를 제안 및 분석하였다. 또한, 시뮬레이션을 통해 본 논문에서 제안하는 방식에 적합한 변조 지수(modulation index)를 분석하였으며 그에 따른 적정 누적 개수 또한 분석하였다. In satellite communication, modulated beacon signal is spreaded by gold sequence and the modulated beacon is transmitted via linear phase modulation. Due to the difference in characteristics of the satellite and the receiver on the ground, frequency offset (FO) occurs. An existing modulated beacon receiver is a method of synchronizing the frequency of a modulated beacon signal using FFT(Fast Fourier Transform), which not only increases the delay and complexity in terms of system implementation but also has a separate circuit for compensating the phase difference due to FO and phase offset from FFT points. In order to overcome this problem, this paper proposes and analyzes a scheme for compensating and demodulating the coarse FO and phase offset at one time using the 2-phase shaped characteristics of the modulated beacon signal. Also, through the simulation, the modulation index suitable for the proposed method is analyzed and the appropriate cumulative number is also analyzed.

Hearing Threshold Shift and Speech Intelligibility Index of Personal Hearing Protective Devices

최철희 한국청각언어재활학회 2013 Audiology and Speech Research Vol.9 No.1

The objective of this study is to investigate the effectiveness of the personal hearing protective devices in terms of the hearing threshold shift and the speech intelligibility index. The hearing threshold shift was used to quantify the protection effect of the personal hearing protective devices and obtained by subtracting the baseline threshold measured without the personal hearing protective devices from the hearing threshold measured with the personal hearing protective devices. The speech intelligibility index (SII) was used to predict and compare the potential benefits of each personal hearing protective device and obtained from the count-the dots method. A total of 6 college students aging from 21 to 25 years old were randomly recruited as subjects. Different types of personal hearing protective devices (earplug and earmuff) were used in this study. A statistically significant difference between the mean amount of threshold shift at low frequency (0.25-1 kHz) and that of high frequency region (2-8 kHz) was observed. The personal hearing protective devices (earplug and earmuff) were effective in protecting hearing from high frequency noises than low frequency noises. The use of earmuff was effective at the low frequency region while the use of earplug was effective at the high frequency region. In addition, the use of the earplug was more effective for the SII than that of the earmuff. The protection amount of the personal hearing protective devices (earplug and earmuff) ranged from 23 to 38 dB. However, the SII ranged from 32.6 to 54.5%, which indicates that the subjects misunderstood or missed the speech information ranged from 45.5 to 67.4% as mild to moderate hearing loss. This may lead to the development of new personal hearing protective devices which are effective for protecting hearing and understanding speech.

Mechanisms and Treatment of Blast Induced Hearing Loss

최철희 대한청각학회 2012 Journal of Audiology & Otology Vol.16 No.3

The main objective of this study is to provide an overview of the basic mechanisms of blast induced hearing loss and review pharmacological treatments or interventions that can reduce or inhibit blast induced hearing loss. The mechanisms of blast induced hearing loss have been studied in experimental animal models mimicking features of damage or injury seen in human. Blast induced hearing loss is characterized by perforation and rupture of the tympanic membrane, ossicular damage, basilar membrane damage, inner and outer hair cell loss, rupture of round window, changes in chemical components of cochlear fluid, vasospasm, ischemia, oxidative stress, excitotoxicity, hematoma, and hemorrhage in both animals and humans. These histopathological consequences of blast exposure can induce hearing loss, tinnitus, dizziness, and headache. The pharmacological approaches to block or inhibit some of the auditory pathological consequences caused by blast exposure have been developed with antioxidant drugs such as 2,4-disulfonyl α-phenyl tertiary butyl nitrone (HXY-059, now called HPN-07) and N-acetylcysteine (NAC). A combination of antioxidant drugs (HPN-07 and NAC) was administered to reduce blast induced cochlear damage and hearing loss. The combination of the antioxidant drugs can prevent or treat blast induced hearing loss by reducing damage to the mechanical and neural component of the auditory system. Although information of the underlying mechanisms and treatment of blast induced hearing loss are provided, further and deep research should be achieved due to the limited and controversial knowledge.

Psychometric and Psychoacoustic Measures of Tinnitus

최철희 한국청각언어재활학회 2012 Audiology and Speech Research Vol.8 No.2

Tinnitus is a ringing in the ears without external sounds from outside. Tinnitus is not a disease but a symptom affecting the quality of life in daily lives. Although many different measures of tinnitus have been developed, it is not easy for clinician to select one or some of these measures to fit the goals of the management of tinnitus. Therefore, the objective of this study is to review a variety of previous studies of tinnitus in terms of psychometric and psychoacoustic measures of tinnitus to provide clinically useful and valuable information to professionals who want to develop a standardized test of tinnitus. This study reviewed a variety of literatures associated with the psychometric measures including tinnitus handicap inventory, tinnitus questionnaire, tinnitus reaction questionnaire, tinnitus handicap questionnaire, tinnitus cognition questionnaire, and tinnitus disability index. The psychoacoustic measures of tinnitus including pitch, loudness, masking, and residual inhibition were thoroughly reviewed. Finally, we investigated whether there is a relationship between the psychometric and psychoacoustic measures of tinnitus. However, the psychometric measures were not clearly and directly related to the psychoacoustic measures. This indicates that they do not test the same attributes or constructs of tinnitus. In addition, this may result from the different natures of tinnitus, different mechanisms and sites of action, and high variability between and within subjects. Although there are considerable disagreements in the measures of tinnitus, this paper will provide clinically useful and meaningful information for developing a standardized test of tinnitus.