디지털 오실로스코프에 의한 Wiener-Khinchin 정리의 시현

정세민,Jung, Se-Min 한국광학회 2013 한국광학회지 Vol.24 No.5

위너-킨친 정리(Wiener-Khinchin)는 어떤 신호의 자기상관 함수(Autocorrelation)가 그 신호의 일율 분광띠(Power Spectrum)에 해당됨을 보이는 것으로써, 분광학 및 통신 공학에서 신호 처리와 관련된 매우 중요한 정리이다. 학부 실험실에서 이 정리를 시현하려면 상관기(Correlator)와 신호 처리 장비와 같은 비교적 고가의 장비가 요구되므로, 정리의 시현이 용이하지 않다. 근래에 들어 디지털 공학의 발전과 함께 보급되고 있는 디지탈 오실로스코프들은 측정 결과의 수치화와 그들에 관한 연산 기능이 포함되어 있어, 이 정리를 간단히 시현시킬 수 있다. 본고에서는 정리의 유도 과정에서 얻어지는 실험 이론과 함께 디지털 오실로스코프를 이용해서 이 정리를 시현시키는 방법을 소개한다. 1930년대에 소개된 정리를 다시 재조명하려는 이유는, 비록 정리가 오래전에 소개되었다고는 할지라도 구체적인 유도 과정이나 물리 분야와 관련된 내용들은 우리에게는 여전히 잘 알려져 있지 않기 때문이다. 유도 과정에서 교류 복소 총저항(Impedence) Z, 역율(Power Factor), 위너 분광곡선의 확장된 물리적 의미와 함께, 나아가, 흑체 복사에서 플랑크(M. Planck)의 양자화에 대한 배경이 자연스럽게 나타나므로, 일반물리학, 현대물리학, 분광학 및 물성실험 등과 관련된 강의에 참고가 될 수 있다고 생각된다. The Wiener-Khinchin theorem, which means that the autocorrelation function of a signal corresponds to the power spectrum of the signal, is very important in signal processing, spectroscopy and telecommunications engineering. However, because of needs for some relatively expensive equipments such as a correlator and the signal processing system, its demonstration in most undergraduate class is not easy so far. Recently, digital oscilloscopes whose functions can be replaced foresaid equipments are marketed with development of digital engineering. In this paper, a simple demonstration of the theorem is given by a digital storage oscilloscope and a personal computer with its theoretical background. The reason that deals again with this theorem which has been introduced in 1930 is that it has been not well informed yet to us and theoretical background of the demonstration is directly introduced from its driving process. Through deriving process of the theorem, some extended physical meanings of the impedance, power, power factor, Wiener spectrum, linear system response and, furthermore, basic idea of the Planck's quantization in the black body theory reveal themselves naturally. Hence it can be referred to lectures in general physics, modern physics, spectroscopy and material characterization experiment.

유도전동기용 인버터를 이용한 고출력 방형파 발생기의 제작

丁世敏 東亞大學校附設基礎科學硏究所 1989 基礎科學硏究論文集 Vol.6 No.1

일반적으로 사용되는 선형 전원장치를 레이저 발진용 전원으로 사용할 경우 장비 규모나 전력 사용효율이 낮은 점 등의 단점이 있다. 본 연구에서는 유도전동기용 전원장치의 하나인 펄스폭 변조방식의 전압형 인버터를 이용해서 선형 전원장치가 가진 단점들이 제거된, 일종의 스윗칭형 전원 장치인 방형파 발생기를 제작하였다. 이것이 가능하게 된 점은 승압을 위해 필요로 하는 변압기가 유도전동기와 동일한 형태인 유도성 부하이지만 전자가 전력전달기의 역할을 하는 반면, 후자는 그 자체가 최종 부하인 점에서 그 기능상 차이가 있기 때문이다. 제작된 방형파 발생기의 제원은 입력 전압220V? (단상/삼상겸용) 출력전압 : 0-±300V?, 출력주파수 : 0-10㎑, 유효전력 :3㎾이다. A high power, high voltage, high frequency square wave generator (SWG)(Effective power: 3KW, Input:220Vac, 1 ?or 3?, Output:0―±300㎑ Vp.Frequency: 0―10㎑) is constructed using an inverter with some modifications. Inverter is well known as the motor power supply of the switcthing type. Its superious properties with respect to the linear power supply system are high power-efficiency, compactness, systmatic control, protection functions and so on. The modifications are the program alteration and the rise of the reference oscillator frequency up to 30㎑. Also, its performance test results on the step-up transformer are reported.

록인 증폭기에 의한 광전효과 실험

정세민 東亞大學校 大學院 1999 大學院論文集 Vol.24 No.-

It is known to us that photo-conductors reveal shot-noise in their operation and this kind of noise can be sucssesfully remove with the lock in amplifier(LIA) Because of the ability of the noise rejection in various circumstanes, the use of the LIA is more frequent than ever, Hence, we need to be farmiliar with the divice and operate skillfuly. For this purpose, author introduces a simple experiment using LIA, i.e. well known Photoelectric Effects. From the experimental result, it can be shown that the maximum energy of emitted photoelectrons is lying from 0.2eV to 0.3eV and the average energy is given by 0.43eV from the curve fitting. The maximum energy can be reasonably accepted from comparision with known data. Also from the fitting, it is found that the energy distribution would rather be a poissonian than maxwellian.

복합 가열 방식에 의한 구리증기 레이저의 제작

丁世敏 東亞大學校 大學院 1987 大學院論文集 Vol.12 No.-

An externally heated copper vapor laser system is a useful device for parametric studies of laser output since the discharge parameter can be controlled without interruption of the tube system. The operation temperature of the copper vapor laser is higher than 1000℃, thus the choice of the heating element is very limited. So, we adopt an hybrid type heating system, in which the kanthal A-1 is selected for an auxiliary heating-element. In this esperiment, the measured laser output power is 0.8W, the optimum temperature is 150 0℃, the optimum discharging rate is 5㎑

학부용 편광계와 543 nm에서 설탕의 비회전 측정

정세민,Jung, Semin 한국광학회 2012 한국광학회지 Vol.23 No.6

광학 활성의 측정은 고분자, 광통신, 천문학, 물리학 등과 관련된 분야에서 매우 중요한 주제가 되고 있다. 따라서 이와 같은 경향은 이 주제를 학부 실험에 반영되도록 할 필요가 있다. 이 실험에서는 파장이 543 nm인 헬륨-네온 레이저와 학부용으로 시판되는 파스코 사의 검출기, 회전 엔코더 및 자료 수집기를 사용해서 저비용으로 믿을만한 결과를 주는 편광계를 구성하고 관련 이론과 실험식을 제시하였다. 장치 성능을 검증하기 위해 반파장판을 표준 시료로 사용했으며, 그 후 농도가 30 %인 설탕 용액을 측정 시료로 사용해 비회전을 측정해 보았다. 설탕의 비회전 측정 결과는 +76 deg.cc/g.dm로써, 기존의 CRC 자료들의 내삽을 통해 추정된 값과 거의 동일했으므로, 대부분 학부 수준의 실험에서도 충분히 수용 가능하다고 판단되었다. Measurements of the optical activity become very important issues in fields related to polymers, optical communications, astronomy, physics and many more. Hence it need to introduce this subject in our regular curriculum. In this experiment, an inexpensive, reliable, motorized polarimeter system which is suitable for undergraduate courses is constructed with PASCO's well-known Science Workshop 750 and a rotational motion sensor and light sensor, and the system is presented along with its experimental formulas. After responsivity of this system was checked by a half wave plate, and some repetitive experiments with 30% sucrose solution at 543.8 nm were performed. Comparing the experimental result with two calculated values from CRC data[1] showed that the specific rotation of the sucrose sample could be strongly suggested to be around +76 deg.cc/g.dm and it was an amply acceptable result for most undergraduate level courses.

Characterisation of optical sensing materials based on ion-pairing for carbon dioxide indicator

정세민,황기섭,이준영 한국고분자학회 2015 한국고분자학회 학술대회 연구논문 초록집 Vol.2015 No.10

Application of moving particle simulation for the motion of a 2-D floating body with leaking oil in waves

정세민,남정우,박종천,윤상문,김성용,조용진 조선대학교 공학기술연구원 2018 공학기술논문지 Vol.11 No.1

In this study, the dynamic behaviors of a two-dimensional section of a floating body in waves are predicted using a modified particle-based method with a turbulence model. To predict the motion of a floating body, the free roll decay problem is simulated using the passively moving-solid model and the results are validated by comparing with the experiments. For the motion analysis on a floating body in waves, several types of cargo condition assumed to be partially-filled with solid and liquid cargos, such as water and oil, are simulated both with and without damage. As a result, the case loaded with liquid cargo showed more stable motion compared to the case with solid cargo. In addition, in the case with oil are damaged, the oil leak from the damaged part as well as the appearance of the leaked oil spilling towards inland sea are confirmed with a time lapse.

탐라해상풍력발전단지가 제주 전력계통에 기여한 경제성 및 환경성 평가에 관한 연구

정세민,오웅진,이연찬,임진택,이기백,최재석 대한전기학회 2020 전기학회논문지 Vol.69 No.7

This paper proposes an evaluation methodology of the economics and environmental contribution of Tamla offshore wind farm which is owned by KOEN(Korea South-East Power Co, Ltd.). The probabilistic simulation system called “PRAWIN,” which has already been developed by this research team, is used in this study. An alternative new methodology in order to evaluate contribution of WTGs(Wind Turbine Generators) in view point of probabilistic production cost (economics) and CO2 emissions (environment) is developed in this paper. Furthermore, the wind speed contribution functions in view point of probabilistic production cost (economics) and CO2 emissions (environment) are newly formulated and proposed in this paper. The proposed contribution functions describe variation coefficients (sensitivities) of the economics (probabilistic production cost) and environment (CO2 emissions) according to changing wind speed of a wind farm. Using the new contribution functions proposed in this paper, Jeju power system sized model case study including Tamla offshore wind farm is demonstrated. The total production cost, average production cost unit and CO2 emissions of Tamla offshore wind farm are simulated and assessed in the case study. Using the proposed contribution functions, also, the contributions of wind speed of Tamla offshore wind farm in view point of economics (probabilistic production cost) and environment (CO2 emissions) are evaluated in this case study. Finally, It is demonstrated that probabilistic production energies, production costs and CO2 emissions of individual power generator are obtained in the case study

Hydrophobic films for optical detection of dry carbon dioxide based on ion pairing and an amine polymer

정세민,이찬민,이준영,황기섭 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.6

Existing optical carbon dioxide sensors using ion pair materials with pH indicators need moisture to function. To sense dry carbon dioxide gas, hydrophobic films were prepared using an amine polymer (branched-polyethyleneimine)instead of water, along with an ion pair dye and an aromatic polymer. The color of the ion pair formedbetween cresol red sodium salt and tetra-n-octylammonium bromide was yellow when the pH was below neutral. After adding branched polyethyleneimine, the color changed to violet as the pH became basic. On exposure to carbondioxide, the amine groups on the branched-polyethyleneimine were converted to alkyl carbamate anions and ammoniumcations via reaction with the carbon dioxide. When the ion pair reacted with the resulting ammonium cations,the film changed color from violet to yellow. It was determined that the degree of color change was dependent on thecarbon dioxide exposure times and the amount of branched-polyethyleneimine added to the film.

항공안전강화를 위한 연구

정세민,황정인,오현식,김학령 한국항공우주의학협회 2023 항공우주의학 학술대회 Vol.2023 No.11