• 대한전기학회논문지:시스템및제어부문D
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• 제55권10호
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• pp.435-442
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• 2006

One of the most important topics about the safety of electrical and electronic system is the reliability of the wiring system. The Time-Frequency Domain Reflectometry(TFDR) is a state-of-the-art system for detecting and estimating of the fault on a wiring. In this paper, We've considered the load resistance measurement on a coaxial cable using TFDR in a way of expanded application. The TFDR system was built using commercial Pci extensions for Instrumentation(PXI) and LabVIEW. The proposed real time TFDR system consisted of the reference signal design, signal generation, signal acquisition, algorithm execution and results display part. To implement real time system, all of the parts were programmed by the LabVIEW which is one of the graphical programming languages. Using the application software implemented by the LabVIEW, we were able to design a proper reference signal which is suitable for target cable and control not only the arbitrary waveform generator in the signal generation part but alto the digital storage oscilloscope in the signal acquisition part. By using the TFDR real time system with the terminal resistor on the target cable, we carried out load impedance measurement experiments. The experimental results showed that the proposed system are able not only to detect the location of impedance discontinuity on the cable but also to estimate the load resistance with high accuracy.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1353-1357
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• 2008

A sea water source cascade heat pump was designed and tested in this study. The system was designed to perform a single stage operation in summer, as well as a cascade operation in winter to ensure the high temperature lift. A steady-state simulation model was developed to analyze and optimize its performance. The simulation results show that the R717 exhibits best performance among combinations considered in this study. A R410A also exhibits the highest performance among HFCs with the smallest compressor displacement. A 15-RT R410A-R134a pilot system was installed in the 5-story commercial building at Samcheok City by the East Sea. A scroll type R410A compressor, a reciprocating type R134a compressor, plate type condenser/ evaporator/ cascade heat exchanger and two electronic expansion valves were used to build a pilot. A titanium plate type heat exchanger is also used for the heat exchanging with a sea water. The heat source/sink water is supplied from the well below the seashore in the depth of 5 m. In the initial test of the system, supply water temperature was rising up to $67^{\circ}C$ using a sea water heat source of $9^{\circ}C$, while an ambient temperature was $4.5^{\circ}C$.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1273-1278
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• 2008

A sea water source cascade heat pump was designed and tested in this study. The system was designed to perform a single stage operation in summer, as well as a cascade operation in winter to ensure the high temperature lift. A steady-state simulation model was developed to analyze and optimize its performance. The simulation results show that the R717 exhibits best performance among combinations considered in this study. A R410A also exhibits the highest performance among HFCs with the smallest compressor displacement. A 15-RT R410A-R134a pilot system was installed in the 5-story commercial building at Samcheok City by the East Sea. A scroll type R410A compressor, a reciprocating type R134a compressor, plate type condenser/ evaporator/ cascade heat exchanger and two electronic expansion valves were used to build a pilot. A titanium plate type heat exchanger is also used for the heat exchanging with a sea water. The heat source/sink water is supplied from the well below the seashore in the depth of 5 m. In the initial test of the system, supply water temperature was rising up to $67^{\circ}C$ using a sea water heat source of $9^{\circ}C$, while an ambient temperature was $4.5^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2371-2376
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• 2009

Three phenoxazine-based conjugated polymers, namely, the aryl substituted phenoxazine homopolymer (P1) as well as the dimeric phenoxazine-fluorene (P2) and phenoxazine-bithiophene (P3) copolymers, were synthesized via the Ni(0) mediated Yamamoto reaction and the palladium-catalyzed Suzuki coupling reaction. The weight-averaged molecular weights ($M_w$) of P1, P2, and P3 were found to be 27,000, 22,000, and 15,000, respectively, and their polydispersity indices were 3.6, 1.8, and 2.1. All the polymers were soluble in common organic solvents such as chloroform, toluene, and so on. The UV-visible absorption maxima for P1, P2, and P3 in the film state were located at 421, 415 and 426 nm, respectively, and the ionization potentials of the polymers ranged between 4.90 and 5.12 eV. All the studied phenoxazine-based polymers exhibited amorphous behavior, as confirmed by X-ray diffraction (XRD) and atomic force microscopy (AFM) studies. Thin film transistors were fabricated using the top-contact geometry. P1 showed much better thin-film-transistor performance than P2 or P3: A thin film of P1 gave a saturation mobility of 0.81 ${\times}\;10^{-3}\;cm^2V^{-1}s^{-1}$ and an on/off ratio of about $10^2$.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.177-181
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• 2014

Pseudo-first-order rate constants ($k_{obsd}$) have been measured spectrophotometrically for the reactions of Y-substituted-phenyl benzoates (5a-j) with potassium ethoxide (EtOK) in anhydrous ethanol at $25.0{\pm}0.1^{\circ}C$. The plots of $k_{obsd}$ vs. [EtOK] curve upward regardless of the electronic nature of the substituent Y in the leaving group. Dissection of $k_{obsd}$ into the second-order rate constants for the reactions with the dissociated $EtO^-$ and ion-paired EtOK (i.e., $k_{EtO^-}$ and $k_{EtOK}$, respectively) has revealed that the ion-paired EtOK is more reactive than the dissociated $EtO^-$. The Br${\phi}$nsted-type plots for the reactions with the dissociated $EtO^-$ and ion-paired EtOK exhibit highly scattered points with ${\beta}_{lg}$ = -$0.5{\pm}0.1$. The Hammett plots correlated with ${\sigma}^o$ constants result in excellent linear correlations, indicating that no negative charge develops on the O atom of the leaving Y-substituted-phenoxide ion in transition state. Thus, it has been concluded that the reactions with the dissociated $EtO^-$ and ion-paired EtOK proceed through a stepwise mechanism, in which departure of the leaving group occurs after the RDS, and that $K^+$ ion catalyzes the reactions by increasing the electrophilicity of the reaction center through a four-membered cyclic TS structure.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.446-446
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• 2011

One dimensional (1-D) structures of ZnO nanorods are promising elements for future optoelectronic devices. However there are still many obstacles in fabricating high-quality p-type ZnO up to now. In addition, it is limited to measure the degree of the doping concentration and carrier transport of the doped 1-D ZnO with conventional methods such as Hall measurement. Here we demonstrate the measurement of the electronic properties of p- and n-doped ZnO nanorods by the Kelvin probe force microscopy (KPFM). Vertically aligned ZnO nanorods with intrinsic n-doped, As-doped p-type, and p-n junction were grown by vapor phase epitaxy (VPE). Individual nanowires were then transferred onto Au films deposited on Si substrates. The morphology and surface potentials were measured simultaneously by the KPFM. The work function of the individual nanorods was estimated by comparing with that of gold film as a reference, and the doping concentration of each ZnO nanorods was deduced. Our KPFM results show that the average work function difference between the p-type and n-type regions of p-n junction ZnO nanorod is about ~85meV. This value is in good agreement with the difference in the work function between As-doped p- and n-type ZnO nanorods (96meV) measured with the same conditions. This value is smaller than the expected values estimated from the energy band diagram. However it is explained in terms of surface state and surface band bending.

• 대한화학회지
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• 제38권8호
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• pp.590-597
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• 1994

유기 리간드(2,2,6,6-테트라메틸-3,5-헵탄내디온)을 란탄나이드 3가$(Pr^{3+}, Eu^{3+}, Gd^{3+} 그리고 Yb^{3+})$와의 착물들에 대한 거동을 UV-Vis 분광학적, 자기적, 그리고 전기화학적 방법에 의해 조사하였다. 2 또는 3개의 에너지 흡수띠가 이들 착물들의 스펙트라에 의해 관찰되었다. 결정장 갈라짐 에너지 크기와 스핀 또는 3개의 에너지 흡수띠가 이들 착물들의 스펙트라에 의해 관찰되었다. 결정장 갈라짐 에너지 크기와 스핀 짝지움 에너지 그리고 결합세기는 착물들의 스펙트라로부터 얻어졌다. 이들은 편재화이고, 낮은 스핀(또는 높은 스핀) 상태이며 그리고 강한 결합세기임을 알았다. 착물들의 거동은 비수용매속에서 순환전압전류법에 의해 관찰하였다. 이들 환원피크는 전자전이에 의한 2 또는 3단계의 비가역성이었다.

• 대한화학회지
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• 제36권1호
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• pp.44-50
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• 1992

착물들의 자기성과 스펙트라의 성질은 d 궤도 함수의 퇴화에 대한 분열과 자외선 가시 분광학적 방법으로 비수용액 속에서 조사하였다. 10Dq의 에너지 크기는 착물들의 스펙트라와 결합에너지 그리고 스핀상태로부터 얻어졌다. 전기화학적 거동은 순환전압 전류법에 의해 측정하였다. 이들의 환원 피크는 Ag/AgCl 전극으로 20mV/s에서 $[(C_6H_5)3_P]_2Pd(II)(CH_3COO)_2$는 $E_{pc1} = -1.32 V,\;E_{pc2} = -1.56 V$이고, 그리고 $[(C_6H_5)_3Pd]_2Pd(II)Cl_2$에서는 $E_{pc1} = -1.74 V,\;E_{pc2} = -1.88 V$로 일전자 비가역적인 과정이었다. 그러나 $Ni^{2+}$ 착물에서는 환원성으로 되지 않았다.

• 한국광학회지
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• 제16권6호
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• pp.494-499
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• 2005

코어가 확산된 단일모드 광섬유와 외부 물질 사이의 분산 특성의 차이를 이용하여 차단 특성이 우수한 단파장 통과 필터(short-pass filter)를 구현하였다. 두 물질의 결합 방법으로 측면 연마 기법을 도입하였다. 실험 결과 소자의 대역경계 파장(band edge wavelength)은 코어의 확산 정도로 조절이 가능하였다. 일반 통신용 단일 모드 대신에 열확산 코어 확산 광섬유를 도입함으로써 더 예리한 파장응답을 얻을 수 있었다. 열광학 효과를 이용하여 경계 파장을 400nm 이상 가변 할 수 있음을 관측하였다.

• 한국재료학회지
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• 제27권1호
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• pp.48-52
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• 2017

In this study, we used I-V spectroscopy, photoconductivity (PC) yield and internal photoemission (IPE) yield using IPE spectroscopy to characterize the Schottky barrier heights (SBH) at insulator-semiconductor interfaces of Pt/$HfO_2$/p-type Si metal-insulator-semiconductor (MIS) capacitors. The leakage current characteristics of the MIS capacitor were analyzed according to the J-V and C-V curves. The leakage current behavior of the capacitors, which depends on the applied electric field, can be described using the Poole-Frenkel (P-F) emission, trap assisted tunneling (TAT), and direct tunneling (DT) models. The leakage current transport mechanism is controlled by the trap level energy depth of $HfO_2$. In order to further study the SBH and the electronic tunneling mechanism, the internal photoemission (IPE) yield was measured and analyzed. We obtained the SBH values of the Pt/$HfO_2$/p-type Si for use in Fowler plots in the square and cubic root IPE yield spectra curves. At the Pt/$HfO_2$/p-type Si interface, the SBH difference, which depends on the electrical potential, is related to (1) the work function (WF) difference and between the Pt and p-type Si and (2) the sub-gap defect state features (density and energy) in the given dielectric.