• Advances in Traditional Medicine
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• 제6권4호
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• pp.274-285
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• 2006

Allium sativum (Family Amaryllidaceae or Liliaceae) is used worldwide for various clinical uses like hypertension, cholesterol lowering effect, antiplatelets and fibrinolytic activity etc. Due to these common house hold uses of Allium sativum, as a herbal supplements, and failure of patients to inform their physician of the over-the-counter supplements they consume leads to drugnutrient interactions with components in herbal supplements. Today these types of interactions between a herbal supplement and clinically prescribed drugs are an increasing concern. In vitro studies indicated that garlic constituents modulated various CYP (cytochrome P450) enzymes. CYP 3A4 is abundantly present in human liver and small intestine and contributes to the metabolism of more than 50% of commonly used drugs including nifedipine, cyclosporine, erythromycin, midazolam, alprazolam, and triazolam. Extracts from fresh and aged garlic inhibited CYP 3A4 in human liver microsomes. The in vivo effects of garlic constituents are found to be species depended and the dosing regimen of garlic constituents appeared to influence the modulation of various CYP isoforms. Studies have indicated that the inhibition of various CYPs by organosulfur compounds from garlic was related to their structure also. Studies using in vitro, in vivo, animal and human models have indicated that various garlic constituents can be the substrates, inhibitors and or inducers of various CYP enzymes. The modulation of CYP enzyme activity and expression are dependent on the type and chemical structure of garlic constituents, dose regime, animal species and tissue, and source of garlic thus this review throws light on the possible herb drug interaction with the use of garlic.

• 한국산업정보학회논문지
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• 제23권4호
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• pp.13-22
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• 2018

본 논문에서는 스크램블 연산(Scramble Operation) 및 위상 천이 디지털 홀로그래피(PSDH; Phase Shift Digital Holography) 기반 영상 이중 암호화 방법을 제안한다. 암호화하고자 하는 영상을 스크램블 연산을 통해 디지털적으로 1차 암호화를 수행한 후, 위상 변조하고, 위상을 천이시킨 기준파와의 간섭을 통해 2차 암호화 정보를 얻는다. 복호화 과정은 암호화 과정의 역순으로 진행된다. 두 개의 암호화된 영상들을 적절하게 산술 처리하는 위상 천이 디지털 홀로그래피 기술을 통해 디지털적으로 1차 복호화하고, 위상 복조를 한 후, 스크램블 연산 시에 사용한 암호화 키 정보를 이용하여 원래의 영상을 복원한다. 제안된 암호화 방법은 스크램블 연산에 사용된 두 개의 키 정보와 위상 천이 디지털홀로그래피 기술에서 사용된 거리 정보, 광원의 파장 등의 정보를 모두 정확하게 알아야만 원래의 영상을 복원할 수 있다.

• 한국광학회지
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• 제17권3호
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• pp.223-230
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• 2006

직접 광주파수 변조된 레이저 다이오드를 광원으로 이용하여 공간 선택적 브릴루앙 산란 방식으로 분포형 광섬유 센서를 구성하여 실험하였다. 광주파수가 정현파로 변조된 펌프와 프로브 빛이 광섬유 내로 서로 반대 방향으로 진행하며 중첩되도록 함으로써 광섬유 내 특정 지점에서만 유도 브릴루앙 산란이 발생하도록 하였으며, 변조 주파수를 변화시켜 브릴루앙 이득 피크의 위치를 조절할 수 있었다. 브릴루앙 천이 주파수가 서로 다른 광섬유를 접속한 경우와 광섬유 길이를 따라 온도 분포가 존재하는 경우에 대해 각각 브릴루앙 천이 주파수의 분포를 측정하였다. 브릴루앙 천이 주파수의 온도 변화율은 $1.33MHz/^{\circ}C$로 측정되었다.

• 조명전기설비학회논문지
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• 제26권9호
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• pp.1-7
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• 2012

In this paper, we present a new lighting control method considering ambient light in addition to the required lighting illumination for efficient energy saving of a LED stand. We estimate accurate environmental illuminance using a cheap illuminance sensor by modeling measured- and actual-illuminance using quadratic polynomial approximation. The relation between PWM(Pulse Width Modulation) duty ratio and illuminance intensity is modeled by a linear model. Illumination of the LED stand is controlled by estimating the difference of required illumination and the estimated ambient illumination. The developed LED stand has reduced electric energy consumption compared with a conventional manually controlled LED stand with the same lighting source. In addition, human subject evaluation shows that the LED stand, which is applied the proposed method, is more satisfactory than conventional ones since the proposed automatic controlled illumination produce more accurately required lighting and it is convenient.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.70-78
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• 2012

Due to the variable nature of renewable energy resources and power demand by consumers, it is difficult to operate a power system installed with only one type of renewable energy resource. Grid-based renewable generation may be the only solution to overcome this problem. The conventional approach based on a low-voltage converter with power frequency transformer is commonly employed for grid connection of offshore renewable energy systems. Because of the heavy weight and large size of the transformer, the system can be expensive and complex in terms of installation and maintenance. In this paper, an 11-kV series connected H-bridge (SCHB) multilevel voltage source converter (VSC) is proposed to achieve a compact and light direct grid connection of renewable energy systems. This paper presents the design, simulation and analysis of a five level (5L)-SCHB and an eleven level (11L)-SCHB VSC for 11-kV grid-based renewable energy systems. The performance, cost, modulation scheme and harmonic spectra of the converter are analyzed.

• 한국통신학회논문지
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• 제32권12B호
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• pp.809-814
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• 2007

본 논문에서는 중앙국(Central of office)에서 반송파가 억제된 광원을 생성하여 파장에 무관한 RSOA기반 양방향 WDM-PON구조를 제안 하였다. 중앙국에 위치한 마흐젠터 모듈레이터 (LiNbO3 Mach Zehnder Modulator)를 이용해서 5 GHz 변조된 반송파가 억제된 광원(Suppressed Optical Carrier)을 만들어 상향 신호 광원으로 전송을 하고 이와 더불어 하향 신호용 광원은 반사형 광증폭기(Reflective Semi-conductor Optical Amplifier)를 이용해서 데이터 변조 후 전송을 하게 된다. 상향 신호는 반송파가 억제된 광원을 광망 전달 장치(Optical Network Unit)보내 다시 데이터 재변조를 하고 증앙국(Central Office)으로 재전송함으로써 파장에 무관한 새로운 양방향 WDM-PON 구조를 실험을 통해 검증하였다.

• 전기학회논문지
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• 제64권2호
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• pp.284-288
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• 2015

The color temperature flexibility-typed Lighting Emitting Diode(LED) lighting control system proposed in this thesis employs Pulse Width Modulation(PWM) technique to control the brightness of LED lighting. The LED lighting used as a light source has 20W downlight composed of two types of LED chips: one is Warm White and the other is Cool white. One multi-sensor module consisting an infrared sensor, an illumination sensor, and a temperature sensor was made, to which Bluetooth wireless communication technique was applied to enable a smartphone application to control lighting brightness and identify the information collected from the sensor. CS-1000, a spectroradiometer, was used to measure LED dimming control and the changing values of a color temperature in eight steps. According to a test, it was found that it was possible to change a color temperature from 3187K of Warm White LED to 5600K of Cool White LED.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.293-296
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• 2002

This paper proposes new driving methods for designing a driver independent of the current property of organic light emitting diodes (OLED) displays. The proposed methods are the Look-Up Table (LUT) and the Pulse Width Modulation (PWM). The LUT is used to handle the amount of the current for driving the OLED display panel and the PWM is applied to represent the gray scale on the OLED display panel. Segment and common drivers were implemented using delay circuits to prevent short-circuit current and a DC-DC converter was designed to supply the drivers with a power source. In particular, tile proposed methods are used for the manufacturing of 1.8" 128$\times$128 dot passive matrix OLED display panel. The designed circuit was fabricated using 0.6w, 2-poly, 3-metal, CMOS process and applied to the Personal Communication System (PCS) phone successfully.ully.

• 조명전기설비학회논문지
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• 제29권11호
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• pp.59-65
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• 2015

By harnessing the thermal hysteresis behavior of vanadium dioxide($VO_2$), we demonstrated multi-resistance states in a two-terminal electronic device based on a $VO_2$ thin film by using a 966nm infrared laser diode as an excitation light source for resistance modulation. Before stimulating the device using 966nm laser pulses, the thermal hysteresis behavior of the device resistance was measured by using a temperature chamber. After that, the $VO_2$ device was thermally biased at ${\sim}71.6^{\circ}C$ so that its temperature fell into the thermal hysteresis region of the device resistance. Six multi-states of the device resistance could be obtained in the fabricated $VO_2$ device by five successive laser pulses with equal 10ms duration and increasing power. Each resistance states were maintained while the temperature bias was applied. And, the resistance fluctuation level was within 2.2% of the stabilized resistance and decreased down to less than 0.9% of the stabilized resistance 5s after the illumination.

• 한국컴퓨터정보학회논문지
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• 제15권3호
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• pp.65-72
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• 2010

역 RZ 부호로 코딩된 하향신호의 재변조를 이용하여 수신단에서 필터의 대역폭을 줄이기 위하여 상향신호가 저속인 비대칭 2.5Gbps/622Mbps 수동 광가입자 망을 제안한다. 하향 데이터의 형태에 따른 재변조한 상향신호의 평균오차율을 이론적으로 분석하고, 매트랩을 이용한 시뮬레이션을 통하여 최적 임계치에 의한 수신감도를 분석한다. 수신신호의 평균오차율을 $10^{-12}$미만으로 얻기 위해서는 수신전력이 약 -26dBm 이상 요구되며, 임계치의 최적치는 0.33으로 설정이가능하여 임계치가 0.5인 종래의 수신기를 사용하는 경우보다 수신감도가약 3dB 개선되는 것을 알 수 있다. 제안 시스템은 임계치의 제어가 불필요하고, 광 네트워크 유니트에서 광원 및 광선로 단국장치에서 제어회로를 제거할 수 있어, 비대칭 쌍방향 데이터 전송에 유용한 방식임을 알 수 있다.