• Current Optics and Photonics
• /
• 제7권6호
• /
• pp.673-682
• /
• 2023

In this paper, a three-key triple data encryption algorithm (TDEA) of a digital cryptosystem based on phase-shifting interferometry is proposed. The encryption for plaintext and the decryption for the ciphertext of a complex digital hologram are performed by three independent keys called a wavelength key k₁(λ), a reference distance key k₂(d_r) and a holographic encryption key k₃(x, y), which are represented in the reference beam path of phase-shifting interferometry. The results of numerical simulations show that the minimum wavelength spacing between the neighboring independent wavelength keys is about δλ = 0.007 nm, and the minimum distance between the neighboring reference distance keys is about δd_r = 50 nm. For the proposed three-key TDEA, choosing the deviation of the key k₁(λ) as δλ = 0.4 nm and the deviation of the key k₂(d_r) as δd_r = 500 nm allows the number of independent keys k₁(λ) and k₂(d_r) to be calculated as N(k₁) = 80 for a range of 1,530-1,562 nm and N(d_r) = 20,000 for a range of 35-45 mm, respectively. The proposed method provides the feasibility of independent keys with many degrees of freedom, and then these flexible independent keys can provide the cryptosystem with very high security.

• 대한화장품학회:학술대회논문집
• /
• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book I
• /
• pp.686-697
• /
• 2003

A new colloidal silver (Ag) system is present in which a fine colloidal Ag is in situ deposited onto functionalized porous poly (ethylene glycol dimethacrylate) (poly (EGDMA)) microspheres. The effectiveness of Ag deposition was investigated considering the surface characteristics of poly (EGDMA) microspheres. The result reported in this study illustrates that the control of surface area and surface functionality (in this study, a hydroxyl group) of poly (EGDMA) microspheres is an important factor that determines practically the degree of deposition of colloidal Ag. The x-ray analysis showed that Ag nanoparticles were dispersed evenly inner and outer surfaces and had a face center cubic (fee) phase. In the preservative efficacy test, the Ag-containing poly (EGDMA) microspheres had a powerful anti-bacterial activity, showing a high potential for a new preservative in cosmetic industry.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
• /
• pp.815-818
• /
• 2002

Mn doped hexagonal phase of ZnS has been studied as a yellow-orange phosphor for the application to fluorescent displays operated at low voltages. It was found that luminescence from $Mn^{2+}$ was increased as the Mn concentration was increased up to1.2 mol% of host lattice. This study has been attempted by adding trivalent ions such as $Al^{3+}$ or $Bi^{3+}$ to ZnS:Mn as an agent to do the efficient incorporation of Mn ions into ZnS:Mn lattice, resulting in a significant improvement in the phosphor performance, especially at low voltages.

• 한국전자파학회논문지
• /
• 제20권10호
• /
• pp.1050-1060
• /
• 2009

본 논문에서는 능동 위상 배열 안테나를 가지는 SAR(Synthetic Aperture Radar)용 X-대역 T/R(Transmit/Receive) 모듈을 설계, 제작하였다. T/R 모듈은 X-대역에서 800 MHz 이상 대역폭을 가지며 이중 편파 운용이 가능하다. 송신 출력 7 W 이상에 잡음지수 3.9 dB 이하를 가진다. 위상과 이득은 6비트 위상변위기와 6비트 디지털 감쇠기에 의해 각각 제어된다. 게다가 제작된 T/R 모듈은 방향성 결합기와 전력분배기로 연결되는 성능 점검/보정 포트를 가진다. LTCC 다층 기판을 사용하여 고직접화 T/R 모듈이 가능하게 하였다. 모든 동작 주파수 대역에서 수신시 RMS 이득 오차는 최대 0.8 dB 이하이고, 송/수신시 RMS 위상 오차는 최대 $4^{\circ}$ 이하로 측정되었고, 또한 시험 결과 T/R 모듈은 요구되는 전기적인 성능을 만족하였다. 이 구조는 능동 위상 배열 SAR용 안테나에 적용될 수 있음을 확인하였다.

• 대한화장품학회지
• /
• 제41권3호
• /
• pp.201-208
• /
• 2015

오가노겔은 반고형상이며 3차원의 네트워크 구조로 이루어진 친유성 용매로 이루어져 있다. 본 연구에서는 유상과 수상에서 모두 난용성 특징을 가진 제니스테인을 포함하는 레시틴 오가노겔을 개발하였다. 이 시스템은 안정할 뿐만 아니라 경피 흡수 실험에서도 높은 흡수율을 보였다. 본 오가노겔 제형에 적합한 원료들을 선별한 결과, 수화된 레시틴, 해바라기유, dipropylene glycol (DPG), polyethylene glycol (PEG)이 이 시스템에서 주로 사용되었다. 레시틴 오가노겔의 제조에 적합한 원료의 함량은 phase ternary diagram 작성을 통하여 결정하였다. 제조된 레시틴 오가노겔을 organoleptic characteristics, stability, pH, rheology, phase transition temperatures, microscopic analysis, skin penetration 실험을 통해 평가하였다. 본 연구 결과를 통해 본 논문에서 제시하는 레시틴 오가노겔 제형은 안정한 상태에서 난용성 물질을 높은 농도로 피부에 효과적으로 전달할 수 있는 제형으로 활용될 수 있을 것이라 생각된다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
• /
• pp.630-633
• /
• 1997

This paper describes a design of a single phase PWM converter for high speed train. Parallel operation and control method of four Quadrant PWM converters are described. Simulation and modelling of the converters is performed. Capacity of the converter/inverter and power circuit for high speed traction system designed. And harmonic contents of AC line current's are analyzed. The results of the simulation are presented.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2008년도 하계학술대회 논문집
• /
• pp.103-105
• /
• 2008

In grid-interconnection system, a fast, robust and precise phase angle detector is most important to grid synchronization and the active power control. The phase angle can be easily estimated by synchronous dq PLL system. On the other hand under unbalanced voltage condition, synchronous dq PLL system has problem that harmonics occur to phase angle or magnitude of grid voltage because of the effect of the negative sequence components. So, To eliminate the negative sequence components, the PLL method using APF (All Pass Filter) in a stationery reference frame to extract positive sequence components under unbalanced voltage condition is researched. In this paper, we propose a new PLL method with decoupling network using APF in a synchronous reference frame to extract the positive sequence components of the grid voltage under unbalanced grid. The cut-off frequency of APF in a synchronous reference frame can be set to twice of the fundamental frequency comparing with that of APF in a stationery reference frame which is the fundamental frequency. The proposed PLL strategy can detect the phase angle quickly and accurately under unbalanced gird voltages. Simulation and experimental results are presented to verify the proposed strategy under different kind of voltage dips.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 C
• /
• pp.1659-1661
• /
• 2003

Recently, diagnostic techniques have been investigated to defect a partial discharge in high voltage electrical equipment. We have studied the characteristics of the acoustic partial discharge originating from the electrical defects in cubicle GIS(C-GIS). An acoustic emission(AE) sensor is used on the enclosure to detect partial discharge source because the sensor is sensitive to stress waves in its frequency range that may not be from a partial discharge source. AE signal is analyzed with phase-magnitude-frequency number(${\Phi}$-V-n) and pulse per second(PPS). Experience result has shown that the omitted acoustic signal has phase dependency and phase shift characteristic according to increase with applied voltage. These result will be helpful to the pattern recognition of the acoustic partial discharge in a C-GIS.

• 한국세라믹학회지
• /
• 제55권6호
• /
• pp.618-624
• /
• 2018

We developed a mass production method that simultaneously controls the phase transformation and crystal size of $TiO_2$ coatings on multiwalled carbon nanotubes (MWCNTs). Initially, MWCNTs were successfully coated with amorphous 15-20-nm-thick $TiO_2$ by an in-situ sol-gel method. As the calcination temperature increased in both air and argon atmospheres, the amorphous $TiO_2$ was gradually transformed into the fully anatase phase at approximately $600^{\circ}C$, a mixture of the anatase and rutile phases at approximately $700^{\circ}C$, and the fully rutile phase above approximately $800^{\circ}C$. The crystal size increased with increasing calcination temperature. Moreover, above $600^{\circ}C$, the size of crystals formed in air was approximately twice that of crystals formed in argon. The reason is thought to be that MWCNTs, which continuously supported the stresses associated with the reconstructive phase transformation, disappeared owing to complete oxidation in air at these high temperatures.

• 한국군사과학기술학회지
• /
• 제20권5호
• /
• pp.673-680
• /
• 2017

In the proposed paper, we designed low noise frequency synthesizer with compact size for Multi-Band. The proposed frequency synthesizer consists of fundamental frequency band(2 GHz) and harmonic frequency band(4 GHz). To improve the phase noise and spurious level of frequency synthesizer, we analyze how the configuration of frequency synthesizer affect the phase noise and design the multi-band's structure. The implemented frequency synthesizer reduce both the phase noise and spurious level. The phase noise is -92.17 dBc/Hz at 1 kHz frequency offset in 2 GHz and -90.50 dBc/Hz at 1 kHz frequency offset in 4 GHz. All spurious signals including fundamental frequency are suppressed at least 20 dBc than the second harmonic frequency.