• 제목/요약/키워드: laser application

검색결과 1,259건 처리시간 0.029초

High Resolution HC$_3$N Observations toward the Central Region of Sagittarius B2

  • H.S-Ching;Oh, M.ishi;M.Morimoto
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • 한국우주과학회 1993년도 한국우주과학회보 제2권2호
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    • pp.17-17
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    • 1993
  • The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70${\pm}$1.32mmHg/min)compared to CF dialyzers(4.32${\pm}$0.55mmHg/min)(p<0.05). However, there was no observable difference in the UFR between the two dialyzers. Neither APD nor UFR showed any significant increase with an increasing number of reuses for up to more than 20reuses. A substantial number of failures observed in APD(larger than 20mmHe/min)on the reused dialyzers(2 out of 40 CP and S out 26 C-DAK) were attributed to the Possible damage on the fibers. The CF 15-11 HFDs which failed APD test did not show changes in the UFR compared to normal dialyzers indicating that APD is a more sensitive test than UFR test to evaluate the integrity of the fibers. 30527 T00401030527 ^x For quantitative measurement of reflected light from a clinical diagnostic strip, a prototype old reflectance photometer was designed. The strip loader and cassette were made to obtain more accurate reflectance parameters. The strip was illuminated at 45˚c through optical fiber and the intensity of reflected light was determined at rectanguLat angle using a photodiode. The kubelka-munk coefficient and reflection optical density were determined ar four different wavelengths(500,550,570 and 610nm) for blood glucose strip. For higher concentration than 300mg/41 about glucose, a saturation state of abforbance was observed at 500,550 and 570nm. The correlation between glucose concentration and parameters was the best at 610nm. 30535 T00401030535 ^x Radiation-induced fibrosarcoma tumors were grown on the flanks of C3H mice. The mice were divided into two groups. One group was injected with Photofrin II, intravenously (2.5mg/kg body weight). The other group received no Photofrin II. Mice from both groups were irradialed for approximately 15 minutes at 100,300, or 500 mW/cm2 with the argon (488nm/514.5 nm), dye(628nm) and gold vapor (pulsed 628 nm) laser light. A photosensitizer behaved as an added absorber. Under our experimental conditions, the presence of Photolfrin II increased surface temperature by at least 40% and the temperature rise due to 300 mW/cm2 irradiation exceeded values for hyperthermia. Light and temperature distributions with depth were estimated by a computer model. The model demonstrated the influence of wavelength on the thermal process and proved to be a valuable tool to investigate internal temperature rise. 30536 T00401030536 ^x We investigated the structural geometry of thirty-eight Korean femurs. The purpose of this study is to identify major geometrical differences between Korean femurs 3nd others that we believe belong to Caucasians so that we would be able to get insights into the femoral component design that fits Asians including Koreans. We utilized computerized tomography (CT) images of femurs extracted from cadavers. The CT images were transformed into bitmap data by using a film scanner, and then analyzed by using a commercially available software called Image v.1.0 and a Macintosh IIci computer.The resulting data were compared with already published data. The major results show that the geometry of the Korean femurs is significantly different from that of Caucasians: (1) the anteversion angle and the canal flare index are greater by the amount of approximately 8˚ and 0.5, respectively, (2) the shape of the isthmus cross section is more round, and (3) the distance between the teaser trochanter and the proximal border of the isthmus is shelter by about 15 mm. The results suggested that the femoral component suitable for Asians should be different from the currently-used components designed and manufactured mostly by European or American companies. 30537 T00401030537 ^x It is well known that nonlinear propagation characteristics of the wave in the tissue may give very useful information for the medical diagnoisis. In this paper, a new method to detect nonlinear propagation characteristics of the internal vibration in the tissue for the low frequency mechanical vibration by using bispectral analysis is proposed. In the method, low frequency vibration of f0( = 100Hz) is applied on the surface of the object, and the waveform of the internal vibration x (t) is measured from Doppler frequency modulation of silmultaneously transmitted probing ultrasonic waves. Then, the bispectra of the signal x (t) at the frequencies (f0, f0) and (f0, 2f0) are calculated to estimate the nonlinear propagation characteristics as their magnitude ratio, w here since bispectrum is free from the gaussian additive noise we can get the value with high S/N. Basic experimental system is constructed by using 3.0 MHz probing ultrasonic waves and the several experiments are carried out for some phantoms. Results show the superiority of the proposed method to the conventional method using power spectrum and also its usefulness for the tissue characterization. 30541 T00401030541 ^x This paper describes the implementation of a computerized radial pulse diagnosis by aids of a clinical expert. On this base, we composed of the radial pulse diagnosis system in korean traditional medicine. The system composed of a radial pulse wave detection system and a radial pulse diagnosis system. With a detection system, we detected Inyoung and Cheongu radial pulse wave and processed it. Then, we have got the characteristic parameters of radial pulse wave and also quantified that according to the method of Inyoung-Cheongu Comparison Radial Pulse Diagnosis. We defined the jugement standard of radial pulse diagnosis system and then we confirmed the possibility for realization of automatic radial pulse diagnosis in korean traditional medicine. 30545 T00401030545 ^x Microspheres are expected to be applied to biomedical areas such as solid-phase immunoassays, drug delivery systems, immunomagnetic cell separation. To synthesize microspheres for biomedical application, "two stage shot growth method" was developed. The uniformity ratio of synthesized microspheres was always smaller than 1.05. And the surface charge density (or the number of ionizable functional groups) of the microspheres synthesized by "two stage shot growth method" was 6~13 times higher than that of the microspheres synthesized by conventional seeded batch copolymerization. As a previous step for biomedical application, adsorption experiments of bovine albumin on microspheres were carried out under various conditions. The maximum adsorbed amount was obtained in the neighborhood of pH 4.5. Isoelectric point of bovine albumin is pH 5.0, so experimental result shows that it shifted to acid area. The adsorption isotherm was obtained, the plateau region was always reached at 2.Og/L (bulk concentration of bovine albumin).The effect of the kind and the amount of surface functional group was also examined. 30575 T00401030575 ^x A medical image workstation was developed using multimedia technique. The system based on PC-486DX was designed to acquire medical images produced by medical imaging instruments and related audio information, that is, doctors' reporting results. Input information was processed and analyzed, then the results were presented in the form of graph and animation. All the informations of the system were hierarchically related with the image as the apex. Processing and analysis algorithms were implemented so that the diagnostic accuracy could be improved. The diagnosed information can be transferred for patient diagnosis through LAN(local area network). 30592 T00401030592 ^x In the conventional infrared imaging system, complex infrared lens systems are usually used for directing collimated narrow infrared beams into the high speed 2-dimensional optic scanner. In this paper, a simple reflective infrared optic system with a 2-dimensional optic scanner is proposed for the realization of medical infrared thermography system. It has been experimentally proven that the intfrared thermography system composed of the proposed optic system has the temperature resolution of 0.1˚c under the spatial resolution of lmrad, the image matrix size of 256 X 240, and tile imaging time of 4 seconds. 30593 T00401030593 ^x In this paper, MIIS (Medical Image Information System) has been designed and implemented using INGRES RDBMS, which is based on a client/server architecture. The implemented system allows users to register and retrieve patient information, medical images and diagnostic reports. It also provides the function to display these information on workstation windows simultaneously by using the designed menu-driven graphic user interface. The medical image compression/decompression techniques are implemented and integrated into the medical image database system for the efficient data storage and the fast access through the network. 30594 T00401030594 ^x In this paper, computerized BEAM was implemented for the space domain analysis of EEG. Trans-formation from temporal summation to two-dimensional mappings is formed by 4 nearest point inter-polaton method. Methods of representation of BEAM are two. One is dot density method which classify brain electrical potential 9 levels by dot density of gray levels and the other is colour method which classify brain electrical 12 levels by red-green colours. In this BEAM, instantaneous change and average energy distribution over any arbitrary time interval of brain electrical activity could be observed and analyzed easily. In the frequency domain, the distribution of energy spectrum of a special band can easily be distinguished normality and abnormality. 30608 T00401030608 ^x Laboratory information system (LIS) is a key tool to manage laboratory data in clinical pathology. Our department has developed an information system for routine hematology using down-sized computer system. We have used an IBM 486 compatible PC with 16MB main memory, 210 MB hard disk drive, 9 RS-232C port and 24 pin dot printer. The operating system and database management system were SCO UNIX and SCO foxbase, respectively. For program development, we used Xbase language provided by SCO foxbase. The C language was used for interface purpose. To make the system use friendly, pull-down menu was used. The system connected to our hospital information system via application program interface (API), so the information related to patient and request details is automatically transmitted to our computer. Our system interfaced with fwd complete blood count analyzers(Sysmex NE-8000 and Coulter STKS) for unidirectional data tansmission from analyzer to computer. The authors suggests that this system based on down-sized computer could provide a progressive approach to total LIS based on local area network, and the implemented system could serve as a model for other hospital's LIS for routine hematology. 30609 T00401030609 ^x To develop an artificial bone substitute that is gradually degraded and replaced by the regenerated natural bone, the authors designed a composite that is consisted of calcium phosphate and collagen. To use as the structural matrix of the composite, collagen was purified from human umbilical cord. The obtained collagen was treated by pepsin to remove telopeptides, and finally, the immune-free atelocollagen was produced: The cross linked atelocollagen was highly resistant to the collagenase induced collagenolysis. The cross linked collagen demonstrated an improved tensile strength. 30618 T00401030618 ^x This paper is a study on the design of adptive filter for QRS complex detection. We propose a simple adaptive algorithm to increase capability of noise cancelation in QRS complex detection with two stage adaptive filter. At the first stage, background noise is removed and at the next stage, only spectrum of QRS complex components is passed. Two adaptive filters can afford to keep track of the changes of both noise and QRS complex. Each adaptive filter consists of prediction error filter and FIR filter The impulse response of FIR filter uses coefficients of prediction error filter. The detection rates for 105 and 108 of MIT/BIH data base were 99.3% and 97.4% respectively. 30619 T00401030619 ^x To develop an artificial bone substitute that is gradually degraded and replaced by the regenerated natural bone, the authors designed and produced a composite that is consisted of calcium phosphate and collagen. Human umbilical cord origin pepsin treated type I atelocollagen was used as the structural matrix, by which sintered or non-sintered carbonate apatite was encapsulated to form an inorganic-organic composite. With cross linking atelocollagen by UV ray irradiation, the resistance to both compressive and tensile strength was increased. Collagen degradation by the collagenase induced collagenolysis was also decreased. 30620 T00401030620 ^x We have developed a monoleaflet polymer valve as an inexpensive and viable alternative, especially for short-term use in the ventricular assist device or total artificial heart. The frame and leaflet of the polymer valve were made from polyurethane, To evaluate the hemodynamic performance of the polymer valve a comparative study of flow dynamics past a polymer valve and a St. Jude Medical prosthetic valve under physiological pulsatile flow conditions in vitro was made. Comparisons between the valves were made on the transvalvular pressure drop, regurgitation volume and maximum valve opening area. The polymer valve showed smaller regurgitation volume and transvalvular pressure drop compared to the mechanical valve at higher heart rate. The results showed that the functional characteristics of the polymer valve compared favorably with those of the mechanical valve at higher heart rate. 30621 T00401030621 ^x Explosive evaporative removal process of biological tissue by absorption of a CW laser has been simulated by using gelatin and a multimode Nd:YAG laser. Because the point of maximun temperature of laser-irradiated gelatin exists below the surface due to surface cooling, evaporation at the boiling temperature is made explosively from below the surface. The important parameters of this process are the conduction loss to laser power absorption (defined as the conduction-to-laser power parameter, Nk), the convection heat transfer at the surface to conduction loss (defined as Bi), dimensionless extinction coefficient (defined as Br.), and dimensionless irradiation time (defined as Fo). Dependence of Fo on Nk and Bi has been observed by experiment, and the results have been compared with the numerical results obtained by solving a 2-dimensional conduction equation. Fo and explosion depth (from the surface to the point of maximun temperature) are increased when Nk and Bi are increased.To find out the minimum laser power for explosive evaporative removal process, steady state analysis has been also made. The limit of Nk to induce evaporative removal, which is proportional to the inverse of the laser power, has been obtained. 30622 T00401030622 ^x N1 and N2 gross neural action potentials were measured from the round window of the guinea pig cochlea at the onset of the acoustic stimuli. N1-N2 audiograms were made by means of regulating stimulant intensities in order to produce constant N1-N2 potentials as criteria for different input tone pip frequencies. The lowest threshold was measured with an input tone pip I5 dB SPL in intensity and 12 KHz in frequency when the animal was in normal physiological condition. The procedure of experimental measurements is explained in detail. This experimental approach is very useful for the investigation of the Cochlear function. Both noN1inear and active functions of the Cochlea can be monitored by N1-N2 audiograms. 30623 T00401030623 ^x In electrical impedance tomography(EIT), we use boundary current and voltage measurements toprovide the information about the cross-sectional distribution of electrical impedance or resistivity. One of the major problems in EIT has been the inaccessibility of internal voltage or current data in finding the internal impedance values. We propose a new image reconstruction method using internal current density data measured by NMR. We obtained a two-dimensional current density distribution within a phantom by processing the real and imaginary MR images from a 4.77 NMR machine. We implemented a resistivity mage reconstruction algorithm using the finite element method and sensitivity matrix. We presented computer simulation results of the mage reconstruction algorithm and furture direction of the research. 30624 T00401030624 ^x A new method of digital image analysis technique for discrimination of cancer cell was presented in this paper. The object image was the Thyroid eland cells image that was diagnosed as normal and abnormal (two types of abnormal: follicular neoplastic cell, and papillary neoplastic cell), respectively. By using the proposed region segmentation algorithm, the cells were segmented into nucleus. The 16 feature parameters were used to calculate the features of each nucleus. A9 a consequence of using dominant feature parameters method proposed in this paper, discrimination rate of 91.11% was obtained for Thyroid Gland cells. 30625 T00401030625 ^x An electrical stimulator was designed to induce locomotion for paraplegic patients caused by central nervous system injury. Optimal stimulus parameters, which can minimize muscle fatigue and can achieve effective muscle contraction were determined in slow and fast muscles in Sprague-Dawley rats. Stimulus patterns of our stimulator were designed to simulate electromyographic activity monitored during locomotion of normal subjects. Muscle types of the lower extremity were classified according to their mechanical property of contraction, which are slow muscle (msoleus m.) and fast muscle (medial gastrocneminus m., rectus femoris m., vastus lateralis m.). Optimal parameters of electrical stimulation for slow muscles were 20 Hz, 0.2 ms square pulse. For fast muscle, 40 Hz, 0.3 ms square pulse was optimal to produce repeated contraction. Higher stimulus intensity was required when synergistic muscles were stimulated simultaneously than when they were stimulated individually. Electrical stimulation for each muscle was designed to generate bipedal locomotion, so that individual muscles alternate contraction and relaxation to simulate stance and swing phases. Portable electrical stimulator with 16 channels built in microprocessor was constructed and applied to paraplegic patients due to lumbar cord injury. The electrical stimulator restored partially gait function in paraplegic patients. 30626 T00401030626 ^x Two-Dimensional modelling of the Cochlear biomechanics is presented in this paper. The Laplace partial differential equation which represents the fluid mechanics of the Cochlea has been transformed into two-dimensional electrical transmission line. The procedure of this transformation is explained in detail. The comparison between one and two dimensional models is also presented. This electrical modelling of the basilar membrane (BM) is clearly useful for the next approach to the further. Development of active elements which are essential in the producing of the sharp tuning of the BM. This paper shows that two-dimension model is qualitatively better than one-dimensional model both in amplitude and phase responses of the BM displacement. The present model is only for frequency response. However because the model is electrical, the two-dimensional transmission line model can be extended to time response without any difficult. 30627 T00401030627 ^x A method has been proposed for the fully automatic detection of left ventricular endocardial boundary in 2D short axis echocardiogram using geometric model. The procedure has the following three distinct stages. First, the initial center is estimated by the initial center estimation algorithm which is applied to decimated image. Second, the center estimation algorithm is applied to original image and then best-fit elliptic model estimation is processed. Third, best-fit boundary is detected by the cost function which is based on the best-fit elliptic model. The proposed method shows effective result without manual intervention by a human operator. 30628 T00401030628 ^x The intelligent trajectory control method that controls moving direction and average velocity for a prosthetic arm is proposed by pattern recognition and force estimations using EMG signals. Also, we propose the real time trajectory planning method which generates continuous accelleration paths using 3 stage linear filters to minimize the impact to human body induced by arm motions and to reduce the muscle fatigue. We use combination of MLP and fuzzy filter for pattern recognition to estimate the direction of a muscle and Hogan's method for the force estimation. EMG signals are acquired by using a amputation simulator and 2 dimensional joystick motion. The simulation results of proposed prosthetic arm control system using the EMf signals show that the arm is effectively followed the desired trajectory depended on estimated force and direction of muscle movements. 30638 T00401030638 ^x A new neural network architecture for the recognition of patterns from images is proposed, which is partially based on the results of physiological studies. The proposed network is composed of multi-layers and the nerve cells in each layer are connected by spatial filters which approximate receptive fields in optic nerve fields. In the proposed method, patterns recognition for complicated images is carried out using global features as well as local features such as lines and end-points. A new generating method of matched filers representing global features is proposed in this network. 30659 T00401030659 ^x An implementation scheme of the magnetic nerve stimulator using a switching mode power supply is proposed. By using a switching mode power supply rather than a conventional linear power supply for charging high voltage capacitors, the weight and size of the magnetic nerve stimulator can be considerably reduced. Maximum output voltage of the developed magnetic nerve stimulator using the switching mode power supply is 3,000 volts and switching time is about 100 msec. Experimental results or human nerve stimulations using the developed stimulator are presented. 30768 T00401030768 ^x In this paper, we describe the design methodology and specifications of the developed module-based bedside monitors for patient monitoring. The bedside monitor consists of a main unit and module cases with various parameter modules. The main unit includes a 12.1" TFT color LCD, a main CPU board, and peripherals such as a module controller, Ethernet LAN card, video card, rotate/push button controller, etc. The main unit can connect at maximum three module cases each of which can accommodate up to 7 parameter modules. They include the modules for electrocardiograph, respiration, invasive blood pressure, noninvasive blood pressure, temperature, and SpO2 with Plethysmograph.

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O/W 용매 증발법을 이용한 PLGA와 덱스트란의 이중층 미립구 제조 (Fabrication of PLGA/Dextran Double-Layered Microspheres by Oil-in-Water Solvent Evaporation Method)

  • 고종태;이재호;이창래;신형식;육순홍;김문석;강길선;이종문;이해방
    • 폴리머
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    • 제29권6호
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    • pp.543-548
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    • 2005
  • 이중층 미립구는 단일층 미립구에 비해서 낮은 초기 방출량과 국소 지항성, 및 약물 방출량 제어 등의 장점 을 갖고 있다. 그러나 포접 방식이 까다롭고 2단계 이상의 제조 과정이 필요하며 특히 미립구 제조 시 크기 조절이 어렵다는 단점을 갖고 있다. 따라서 본 연구에서는 락타이드글리콜라이드 공중합체(PLGA)와 덱스트란의 서로 다른 고분자를 초고주파 분쇄 유무에 따른 수중유형(O/W) 용매 증발법을 이용하여 이중층 미립구를 제조하였다. 또한 PLGA의 농도에 따라 미립구 크기의 변화를 연구하였다. 이중층 미립구는 전자주사현미경, 동초점 형광 레이저현미경(CFLM), 캠스코프를 이용하여 조사하였다. 제조된 이중층 미립구의 외부층이 매끄러운 구형의 형태를 나타냄을 확인할 수 있었으며, 절단시 내부층과 외부층의 형태를 확실히 구분할 수 있었다. 이에 외부층과 내부층의 구성 물질을 확인하고자 플루오르신-5-이소시아네이트-덱스트란(FITC-덱스트란)을 이용해 CFLM을 관찰한 결과 형광을 띠는 덱스트란으로 구성된 내부층과 형광을 띠지 않는 PLGA 외부층을 관찰하였다. 또한 PLGA의 함량에 따른 미립구의 크기는 전체적으로 증가하는 경향을 확인하였다. 이와 같은 결과로부터 비교적 간단한 수중유형 용매 증발법을 이용하여 PLGA와 덱스트란의 이중층 미립구의 제조가 가능함을 확인할 수 있었다.

Growth and characterization of MgZnO grown on R-plane sapphire substrate by plasma-assisted molecular beam epitaxy

  • Han, Seok-Kyu;Kim, Jung-Hyun;Hong, Soon-Ku;Lee, Jae-Wook;Lee, Jeong-Yong;Kim, Ho-Jong;Song, Jung-Hoon;Yao, Takafumi
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 추계학술대회 논문집
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    • pp.114-114
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    • 2009
  • ZnO has received considerable attention due to its potential applicability to optoelectronic devices such as ultraviolet-light emitting diodes (UVLEDs) and laser diodes (LDs). As well known, however, polar ZnO with the growth direction along the c-axis has spontaneous and piezoelectric polarizations that will result in decreased quantum efficiency. Recently, nonpolar ZnO has been studied to avoid such a polarization effect. In order to realize applications of nonpoar ZnO-based films to LEDs, growth of high quality alloys for quantum well structures is one of the important tasks that should be solved. $Mg_xZn_{1-x}O$ and $Cd_xZn_{1-x}O$ is ones of most promising alloys for this application because the alloys of ZnO with MgO and CdO provide a wide range of band-gap engineering spanning from 2.4 to 7.8 eV. In this study, we investigated on $Mg_xZn_{1-x}O$ films grown with various Mg/Zn flux ratios The films were grown on R-plane sapphire substrates by plasma-assisted molecular beam epitaxy (PAMBE). we investigated on $Mg_xZn_{1-x}O$ films grown with various Mg/Zn flux ratios. The films were grown on R-plane sapphire substrates by plasma-assisted molecular beam epitaxy (PAMBE). With the relatively low Mg/Zn flux ratios, a typical striated anisotropic surface morphology which was generally observed from the nonpolar (11-20) ZnO film on r-plane sapphire substrates. By increasing the Mg/Zn flux ratio, however, additional islands were appeared on the surface and finally the surface morphology was entirely changed, which was generally observed for the (0001) polar ZnO films by losing the striated morphology. Investigations by X-ray $\Theta-2{\Theta}$ diffraction revealed that (0002) and (10-11) ZnO planes are appeared in $Mg_xZn_{1-x}O$ films by increasing the Mg/Zn flux ratio. Further detailed investigation by transmission electron microscopy (TEM) and photoluminescence (PL) will be discussed.

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Impedance Spectroscopy Analysis on the LaAlO3/SrxCa1-xTiO3/SrTiO3 Hetero-Oxide Interface System

  • Park, Da-Hee;Kwon, Kyoung-Woo;Park, Chan-Rok;Choi, Yoo-Jin;Bae, Seung-Muk;Baek, Senug-Hyub;Kim, Jin-Sang;Hwang, Jin-Ha
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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    • pp.188.2-188.2
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    • 2015
  • The presence of the conduction interface in epitaxial $LaAlO_3/SrTiO_3$ thin films has opened up challenging applications which can be expanded to next-generation nano-electronics. The metallic conduction path is associated with two adjacent insulating materials. Such device structure is applicable to frequency-dependent impedance spectroscopy. Impedance spectroscopy allows for simultaneous measurement of resistivity and dielectric constants, systematic identification of the underlying electrical origins, and the estimation of the electrical homogeneity in the corresponding electrical origins. Such unique capability is combined with the intentional control on the interface composition composed of $SrTiO_3$ and $CaTiO_3$, which can be denoted by $SrxCa1-_xTiO_3$. The underlying $Sr_xCa1-_xTiO_3$ interface was deposited using pulsed-laser deposition, followed by the epitaxial $LaAlO_3$ thin films. The platinum electrodes were constructed using metal shadow masks, in order to accommodate 2-point electrode configuration. Impedance spectroscopy was performed as the function of the relative ratio of Sr to Ca. The respective impedance spectra were analyzed in terms of the equivalent circuit models. Furthermore, the impedance spectra were monitored as a function of temperature. The ac-based characterization in the 2-dimensional conduction path supplements the dc-based electrical analysis. The artificial manipulation of the interface composition will be discussed towards the electrical application of 2-dimensional materials to the semiconductor devices in replacement for the current Si-based devices.

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세팔 별모양 폴리스타이렌 사슬의 팽창에 대한 만능 환산 온도 파라미터의 적용 (Application of Universal Scaled Reduced Temperature Parameter to the Three-Arm Star Polystyrene)

  • 박일현;김용철
    • 폴리머
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    • 제27권3호
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    • pp.255-264
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    • 2003
  • 세팔 별모양 폴리스타이렌 (PS, $M_{w}$=2.80$\times$$10^{5}$ , 2.49$\times$$10^{6}$ g/mol)의 여러 종류의 사슬 크기를 t-decalin 용액의 온도 20~7$0^{\circ}C$ 사이에서 점성도법, 레이저 광산란법을 이용하여 측정하였다. 별모양 고분자들의 팽창이 만능성을 갖기 위하여서는 그들 자신의 교란되지 않은 회전 반경 $R_{G,Br,o}$이 포함된 (N/ $R_{G,Br,o}$$^{2}$)$^{3}$2/$ au$/$\tau$$_{C}$ 파라미터가 사용될 것으로 예측하였으나, 실험 결과는 오히려 선형 폴리스타이렌 고분자의 교란되지 않은 회전 반경이 사용된 (N/ $R_{G,Br,o}$$^{2}$)$^{3}$2/$\tau$/$\tau$$_{C}$ 파라미터가 보다 우수한 만능성을 보여 주었다. 이러한 이유는 가지 효과가 $\tau$/$\tau$$_{C}$(=[(Τ-Θ$_{Tc}$ )/Θ$_{Tc}$ ]/[(Θ$_{Tc}$$_{c}$)/ $T_{c}$])부분에서 이미 반영되어 척도 상수 N/ $R_{G,O}$$^{2}$ 부분에서는 나타나지 않는 것으로 생각되어진다. 여기서 N은 고분자 사슬을 이루고 있는 단량체의 개수, Θ$_{Tc}$ 는 고분자의 분자량이 무한대일 때의 임계 용액 온도로써의 Θ 온도를 각각 의미한다.미한다.미한다.다.

생균활성 보존을 위한 유산균 미세캡슐 개발 (Development of Probiotic Microcapsules for the Preservation of Cell Viability)

  • 이강휘;장금일;이윤복;손헌수;김광엽
    • 한국식품과학회지
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    • 제39권1호
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    • pp.66-70
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    • 2007
  • 본 연구에서는 생균제로서의 L. fermentum YL-3의 미세캡슐화를 시도하였고, 균체에 대한 캡슐 재료의 영향을 조사함으로써 캡슐제조시 균에 대한 손상을 최소화하고자 하였다. 그리고 제조된 캡슐의 내산성과 저장성을 조사하여 유산균의 내산성과 저장능의 증진에 적합한 캡슐의 제조 및 보존 방법을 연구하였다. 먼저, 인체에 무독성인 sodium alginate를 캡슐의 원료로 선택하여 microcapsule을 제조한 결과 생균제가 alginate 캡슐에 포집되어 존재하는 것을 확인할 수 있었고, pH 2에서 120-126 ${\mu}m$ 크기의 견고한 캡슐을 제조하였으며, pH가 증가할수록 크기가 커지지만 pH 3 이상에서는 견고성이 너무 떨어져 캡슐의 형성이 어려워 오히려 pH 3에서의 캡슐보다 작은 형태를 나타내었다. 반면, 캡슐 후의 생균제의 생존율은 pH가 증가할수록 높게 나타났다. 그리고 캡슐제조시 사용되는 재료가 균체에 미치는 영향을 조사한 결과 캡슐의 주재료인 sodium alginate와 $CaCl_{2}$는 균의 활성을 떨어뜨리는 것으로 조사되었고, 그 외의 재료인 sodium citrate, Tween 80, Span 80, soybean oil은 균의 활성에 별다른 영향을 주지 않는 것으로 나타났다. 또한 microcapsule과 macrocapsule을 제조하여 각각의 캡슐의 내산성과 저장성을 비교한 결과, 내산성은 microcapsule이 가장 우수한 것으로 나타났고, 저장성은 $4^{\circ}C$에서는 microcapsule, $25^{\circ}C$에서는 macrocapsule에서의 생균제 활성이 좋은 것으로 확인되었다.

Dry-ice Pellet Cleaning 적용 옥외 금속문화재 표면 페인트 및 유성물질 제거방법 비교 연구 (Application Study of Dry-ice Pellet Cleaning for Removing Oil Paint and Lacquer of Outdoor Metal Artifacts)

  • 이지은;조남철;이종명;유재은
    • 보존과학회지
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    • 제28권3호
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    • pp.217-228
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    • 2012
  • 문화재의 훼손은 다양한 형태로 발생된다. 특히 옥외에 노출되어 있는 금속문화재의 표면 손상은 인위적인 훼손인 페인트나 유성물질 성분의 낙서 등과 같은 행위로 유물의 역사적, 미술사적 가치를 저하시킨다. 그러므로 본 연구에서는 친환경적이고 인체에 무해한 dry-ice pellet cleaning을 페인트 및 유성물질을 제거하는데 적용하였으며 결과를 습포법과 비교하였다. 실험 결과 습포법으로 제거할 경우 유성페인트는 제거는 되었으나 금속 표면에 얼룩이 남아 있었으며 락카 스프레이는 제거가 잘 이루어지지 않고 수지가 들떠 있는 현상이 나타났다. Dry-ice pellet cleaning으로 유성페인트를 제거한 경우 표면관찰, 색도계, FT-IR, SEM 분석을 통해 유물 표면에 손상 없이 깨끗하게 제거되었으며 락카 스프레이로 제거한 경우 육안 관찰로는 깨끗하였으나 SEM 관찰 결과 미세 입자가 표면에 남아있는 것이 관찰되었다. 그러므로 본 연구를 통해 dry-ice pellet cleaning의 대체 가능성과 한계성을 함께 확인할 수 있었다.

소형위성용 모터 구동형 포커싱 메커니즘 (A Motor-Driven Focusing Mechanism for Small Satellite)

  • 정진원;최준우;이동규;황재혁;김병규
    • 항공우주시스템공학회지
    • /
    • 제12권4호
    • /
    • pp.75-80
    • /
    • 2018
  • 위성용 카메라의 경우 광학계의 초점을 제어하기 위한 포커싱 메커니즘이 필수적이다. 그러나 국내의 위성용 광학계 포커싱 메커니즘 관련 연구는 시작 단계이며, 관련 보유 기술 또한 열제어형에 국한되어있다. 따라서 본 논문에서는 소형위성용 광학계에 적용 가능한 모터 구동형 포커싱 메커니즘을 제안하였다. 제안된 메커니즘은 모터 구동에 의해 secondary mirror에 z축 변위를 발생시키도록 설계하였다. 또한 서포터에 flexure hinge를 설치하여 사전하중을 가하도록 하여 메커니즘내 부품간 제작공차 및 조립공차로 인한 정렬도 오차를 최소화하도록 하였다. 메커니즘 제작 후 LVDT 센서(linear variable differential transformer sensor)와 레이저 변위측정기로 정렬도(de-space, de-center, tilt)를 측정한 결과 소형위성광학계에 적용 가능한 수준의 정렬도를 갖는 것을 확인하였다.

치아우식 예방을 위한 치아미백기의 활용 : 광역동 치료로서의 접근 (Application of Teeth Whitening LED for Prevention of Dental Caries : Antimicrobial Photodynamic Therapy Approach)

  • 박초아;박호원;이주현;서현우;이시영
    • 대한소아치과학회지
    • /
    • 제47권1호
    • /
    • pp.70-77
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    • 2020
  • 이 연구의 목적은 악궁 전반적으로 조사가 가능한 미백 LED를 이용하여 우식원성 Streptococcus mutans에 대한 광역동 치료의 효과를 알아보기 위한 in vitro 연구이다. S. mutans를 각각 두가지 다른 단계의 상태로 배양하였다. Planktonic 상태와 Hydroxyapatite disk와 CDC biofilm reactor를 5일간 사용하여 동적인 바이오필름 상태를 형성하였다. 20 μM 로 희석한 erythrosine을 5분간 전처리한후 가정용 미백기와 진료실 미백기를 사용하여 각 15분씩 광조사를 시행하였다. 실험 종료 후 각 실험군의 Colony Forming Unit를 측정하였으며 공초점 레이저 현미경를 이용하여 각 조건에 따른 광역동 치료 효과를 비교하였다. 실험 결과 S. mutans에 대한 aPDT효과는 control군과 비교시에 각각 플랑크토닉상태와 동적인 바이오필름 상태에서 모두 통계적으로 유의한 광역동 치료 효과가 나타났다(각각 p = 0.001, p = 0.002). 하지만 동적인 바이오필름 상태에서는 플랑크토닉 상태보다 광역동치료에 내성을 지녀 항미생물 효과가 떨어지는 양상이 관찰되었다. 진료실용 미백 LED와 가정용 미백LED는 유사한 항미생물 효과를 나타냈다. 구강악궁 전반적 조사가 가능한 미백용 LED는 우식의 원인이 되는 S. mutans 바이오필름에 유의한 광역동 치료의 효과를 나타냈으며, 이러한 결과는 치아 우식 예방으로의 광역동 치료의 임상적 적용 가능성을 제시한다.

Silver diamine fluoride가 타액 생물막에 미치는 영향 (The Effect of Silver Diamine Fluoride on Salivary Biofilm)

  • 서미경;송지수;신터전;현홍근;김정욱;장기택;이상훈;김영재
    • 대한소아치과학회지
    • /
    • 제47권4호
    • /
    • pp.406-415
    • /
    • 2020
  • Silver diamine fluoride(SDF)는 우식의 정지를 위해 사용될 수 있는 효과적이고 경제적인 약제로, 협조가 힘든 환자나 의과적인 문제로 치료를 받기 힘든 경우 등에서 사용될 수 있다. 이 연구는 타액 생물막을 이용하여 SDF 의 항미생물효과를 평가하고자 시행되었다. 타액을 이용하여 획득피막 유사 구조를 형성한 후, 타액과 Streptococcus mutans를 첨가하여 우식원성의 타액 생물막을 형성하였다. 타액 생물막에 SDF 를 처리한 결과, 전체 미생물과 S. mutans의 수가 유의하게 감소하였다(p < 0.000). CLSM에서도 생물막 내 죽은 세포가 증가하였다. 유치 법랑질과 상아질 시편에 SDF를 처리한 후 우식원성의 생물막을 배양한 결과, SDF 를 처리할 경우 생물막 형성이 저해되는 것을 확인할 수 있었다(p = 0.029). 연구 결과 SDF의 뛰어난 항미생물효과를 확인할 수 있었으며, 이로 인한 임상에서의 항우식효과를 기대할 수 있다.