• 한국정보전자통신기술학회논문지
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• 제15권4호
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• pp.223-229
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• 2022

본 논문은 보일러에 사용되는 점화트랜스에 대해 연구를 하였다. 점화봉 길이와 점화봉 간격 변화에 관계없이 출력주파수는 59.5~61.3Hz 사이에서 측정되었고 저주파 회로는 정상적으로 동작된 것을 알 수 있었다. 점화봉 간격이 2~10mm 변화를 주었을 때, 점화봉 길이가 30cm에서는 2.8A에서 3.45A까지 측정되었다. 점화봉 길이가 500cm에서는 9.37A에서 14.5A까지 측정되었고 1000cm에서는13.2A에서 32.6A까지 측정되었다. 점화봉 길이와 점화봉 간격이 증가 될수록 전류는 증가되었다. 2차코일 출력전압을 측정한 결과. 점화봉 길이가 30cm에서는 AC 0.84kV~AC 1.75kV로 측정되었고 500cm 인 경우는 AC 1.17kV~AC 1.944로 측정되었고 1000cm에서는 AC 1.4kV~AC 7.18kV까지 측정되었다. 점화봉 길이와 점화봉 간격이 증가되면 2차코일 출력전압도 증가되었다. 점화트랜스의 출력전압 측정한 결과, 점화봉 길이가 30cm에서는 DC 1.11kV~DC 1.57kV 까지 측정되었고 500cm 인 경우는 DC 2.49kV~DC 3.72kV, 1000cm에서는 DC 3.78kV~DC 9.42kV까지 측정되어서 점화봉 길이와 점화봉 간격이 증가되면 출력전압이 증가된 것을 알 수 가 있었다.

• Journal of Preventive Medicine and Public Health
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• 제24권1호
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• pp.86-92
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• 1991

To test if exposure history to rifle fire or cannonade training during military duty can induce hearing loss, history of personal military service and histroy of gunshot exposure were asked to 228 male college students with self -administrative questionnaire. Otoscopic examination and Rinne's test were performed if any abnormal finding was detected by pure-tone audiometry. Average hearing threshold levels of 500 Hz, 1,000 Hz, 2,000 Hz, 4,000 Hz and threshold levels at 4,000 Hz were calculated for 112 students who were remained after exclusion of cases with history of ear disease, of ototoxic drug administration, and of neuropsychiatric disease, and mean of those were compared between group of students who have completed military duty (completed group) and group of those who have not (not-completed group), and between group exposed (exposed group) and group unexposed to gunshot sound (unexposed group). Mean of average hearing threshold level and mean of threshold levels at 4,000 Hz of completed group and those of exposed group were higher than those of not-completed group and unexposed group, respectively. Proportion of cases that average threshold level was greater than 40 dB or threshold levels at 4,000 Hz was greater than 50 dB were higher also in completed group and exposed group than in duty not-completed group and unexposed group, respectively Multiple linear regression analysis including age, duration of military service, degree of gunshot sound exposure as independant variables and average hearing threshold level as dependant variable, was performed in order to estimate the effect of age on hearing, and any considerable effect of age on hearing could not be found. In conclusion, hearing impairment can be induced by rifle fire or cannonade training.

• 한국산업보건학회지
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• 제1권1호
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• pp.56-61
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• 1991

This Study was carried out to measure the noise and to evalulate the prevalence of the noise-induced hearing loss and the hypertension in metal manufacturing workers. To perform this sutdy 116 workers were tested their hearing level and hypertension. 1. In frequency analysis, the $C_5$-dip phenomenon occurred around 4000 Hz. 2. Noise intensity was correlated significantly with hearing loss at 500, 1,000, 8,000 Hz (p<0.01). 3. Average hearing loss value by 4-divided method was $32.91{\pm}5.60dB$. 4. Hearing loss steadily increased to the 10th year and steadily after that at 4000 Hz. 5. The prevalence of noise-induced hearing loss of 6,027 workers was 1.81 %. 6. The prevalence of hypertension of 116 workers was 11.2 %.

• 한국통신학회논문지
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• 제21권2호
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• pp.526-533
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• 1996

In this paper, the 800 MHz band N fractional frquency synthesizer having 677 channel with 30 kHz channel bandwidth is designed on the based on the theory which is dervied in terms of the relation between reference freqiency and the number of channels, loop bandwidth and acquistion time. The experimental resuls show 10 Hz deviation from the bandwidth and acquisition time. The experimental results show 10 Hz deviation from the bandwidth, the spurious suppression of aroud -45 dBc and the acqusition time of 1.44 ms. The results satisfy the given specification, but don't achieve thebesired spurious -60 dBc suppression. It is found that 500 hop per second will be possible over the range from 800 to 820 MHz.

• 한국항공우주학회지
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• 제46권7호
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• pp.567-574
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• 2018

스월은 연료의 후퇴율 증가뿐 아니라 연소 압력의 진동을 감소시키며, 하이브리드 로켓의 연소안정화에 기여하는 것으로 알려져 있다. 따라서 스월 산화제 분사에 의한 주연소실 내부의 유동 구조의 변화를 이해하고 연소안정화의 물리적 과정을 실험적으로 연구하였다. 결과에 의하면, 스월은 주연소실의 유동 구조를 변화시켜 후연소실의 500Hz 대역 p'과 q'의 발생을 억제할 뿐 아니라 두 진동의 위상차를 변화하여 상호결합(coupling)에 영향을 주고 있음을 확인했다. 또한 후연소실 화염 가시화를 통하여 스월에 의한 선회운동량의 증가로 와류발생과 흘림 등이 변화하여 연소안정화에 기여하는 것으로 분석됐다.

• 한국항행학회논문지
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• 제6권1호
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• pp.62-68
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• 2002

해상에 추락한 선원을 구조하기 위해서는 사고 발생 정보를 신속하게 본선에서 알 수 있어야 한다. 이 연구에서는 보급이 용이하도록 형식검정을 받아 별도의 허가절차 없이 사용이 가능하도록 하기 위하여 전파법규에서 특정 소출력 무선국이라고 규정된 447 MHz대를 사용하였다. 이 장치는 송신기의 센서가 물에 접촉되면 작동한다. 500 Hz 구형파로 변조된 전파를 송신하고, 수신기에서 이를 판독하여 경보음을 울리는 시스템이다. 도달거리는 1.5 km이상이다. 또한, 야간 식별을 위하여 송신기는 일정 간격으로 섬광을 발사한다. 인명구조용으로 활용하는 것은 물론 2,400 bps 이하의 저속 데이터의 전송에도 사용이 가능하여 다른 목적의 시스템에도 사용할 수 있다.

• 전력전자학회논문지
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• 제5권2호
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• pp.192-199
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• 2000

본 논문은 고주파 유도 가열기의 전력조절을 위해 뉴로-퍼지 알고리즘을 이용하고, IGBT를 사용한 위상 전이 펄스변조(PSPM)와 주파수 추종 펄스변조(FEPM) 가 조절되는 공진 고주파 인버터를 응용한 유도가열기를 설명한다. 이는 실제로 산업 현장에서 20KHz~500KHz 유도 가열 및 유도 용해 전원장치용으로 쓰인다. 위상 전이 펄스변조 (PSPM) 정전력 조절 기술을 바탕으로 한 적응 주파수 추종기법은 스위칭 손실을 최소화하고 전력조절을 용이하게 하기 위해 소개되어졌다. 뉴로-퍼지제어기를 사용하여 만들어진 실험장치는 성공적인 논증과 토의가 되어졌다.

• 한국항공우주학회지
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• 제45권5호
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• pp.401-408
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• 2017

본 논문에서는 저가 하드웨어 기반의 멀티로터용 비행제어 컴퓨터의 하드웨어 개발과 항법 및 제어 알고리즘의 설계 및 구현, 그리고 실제 비행실험을 통한 검증 과정을 서술하였다. 개발된 비행제어 컴퓨터는 마이크로컨트롤러를 통하여 멀티로터를 안정적으로 제어하며 통합된 Linux 컴퓨터를 활용하여 복잡한 임무에 대응이 가능하도록 설계되었다. 항법 해는 Complementary Filter를 통하여 500 Hz의 속도로 계산을 수행하고, 멀티로터의 운동모델을 기반으로 Observer를 설계, 측정 잡음을 크게 줄였다. 제어 알고리즘은 3차원 Curve Fitting을 통하여 얻은 Feed-forward Term을 사용하여 반응속도를 크게 향상시켰으며, 다수의 비행실험을 통하여 실제 상황에서 효과적으로 동작함을 확인하였다.

• 한국어병학회지
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• 제20권3호
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• pp.307-313
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• 2007

In this study, a QCM biosensor was made to detect Edwardsiella tarda (E. tarda) using a specific antibody. A 9 MHz AT-cut piezoelectric wafer layered with two gold electrodes of 5mm diameter had a reproducibility of 0.1 Hz in frequency response and was used as the transducer of the QCM biosensor. Self assembled layer (SAM) was conformed on a quartz crystal by treating with 3-mer-captopropionic acid (MPA) and activated with N-ethyl-N'-(3-dimethyl-aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The resulting NHS group was further converted to hydrazide by the reaction with hydrazine. Aldehyde group was introduced into the carbohydrate moiety of anti-E. tarda antibody by the reaction with periodic acid and was used to immobilise the antibody through the reaction with hydrazide group on the electrode surface. A baseline was established in the presence of phosphate-buffered saline (PBS) and a resonant frequency (F1) was measured. Sample was added to the sensor surface and second resonant frequency (F2) was measured after unbound substances were washed out with PBS several times. Finally, the frequency shift (ΔF) representing the mass change was calculated by subtracting F2 from F1. After adding the oxidized anti-E. tarda antibody to the electrode surface containing hydrazide group, frequency shift of 288.811.4 Hz (mean S.E) was observed, thus proving that considerable amount of antibody was immobilized. In the immunoassay test, the frequency shift of 1877.75 Hz, 580.67 Hz, 221.39 Hz, 7.671.83 Hz (mean S.E) were observed at doses of 1000, 500, 100, 50 g of bacterial cells, respectively. It was also demonstrated that the prepared sensor chip was stable enough to withstand repeated surface regeneration with 0.2 M Tris-glycine and 1 % DMSO, pH 2.3 more than ten times.

• 한국산업보건학회지
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• 제17권2호
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• pp.153-159
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• 2007

Usually equal noise exposure is considered to cause symmetrical hearing loss, but some screening audiometries of employees who were exposed to noise showed asymmetry. Therefore, this study was carried out to evaluate the distribution of asymmetrical hearing loss and the difference of air conduction level between left and right ear at the different frequencies (500, 1,000, 2,000, 3,000, 4,000, 6,000 Hz). Study subjects were 326 male employees who had participated in the noise-specific health examination from May to October, 2002. They were evaluated by otoscopic examination, pure tone audiometry and tympanometry. In all frequencies, hearing threshold level of left ear was worse than right ear. The mean interaural threshold differences between two ears were 0.83 dB at 500 Hz, 1.18 dB at 2,000 Hz, 2.29 dB at 3,000 Hz, 2.18 dB at 4,000 Hz, and statistically significant (p<0.05). The hearing loss of left ear was greater than right ear in occupationally noise-exposed workers. It is believed that left ear was more susceptible to noise damage than right ear