• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.194.2-194.2
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• 2015

본 논문에서는 InP 기판에 자발형성법 (Self-assembled Mode)으로 성장한 InAs/InAlGaAs 양자점(Quantum Dots)의 외부 열처리 온도에 따른 광학적 특성을 논의한다. 분자선증착기 (Molecular Beam Epitaxy, VH80MBE)로 5주기 적층구조를 갖는 InAs/InAlGaAs 양자점 시료 (기준시료)를 성장 후 온도 의존성 및 여기광세기 의존성 포토루미네슨스 (photoluminescence, PL) 분광법으로 기본특성을 평가하였다. 양자점 시료를 $500{\sim}800^{\circ}C$에서 열처리를 수행하고 광학적 특성을 열처리 전과 비교하여 분석하였다. $550^{\circ}C$에서 열처리한 InAs/InAlGaAs 양자점 시료의 저온 (11K) PL 파장은 1465 nm를 보였으며, 이는 열처리를 하지 않은 기준시료의 1452 nm 보다 13 nm 장파장으로 이동하였다. 열처리 온도가 $700^{\circ}C$ 이상인 경우, 양자점 PL 파장이 다시 단파장으로 이동하는 현상을 보였지만 여전히 열처리하지 않은 기준시료보다 장파장을 나타내었다. $700^{\circ}C$에서 열처리한 양자점 시료의 저온 PL 광세기는 기준시료보다 15.5배 더 크게 나타났으며, 주변 온도가 증가할수록 더디게 감소하는 것을 확인할 수 있었다. 온도의존성 PL로부터 구한 활성화에너지 (Activation Energy)는 $700^{\circ}C$ 열처리 온도의 경우 175.9 meV를 나타내었다. InAs/InAlGaAs 양자점 시료의 열처리 온도에 따른 광특성 변화를 InAs 양자점과 InAlGaAs 장벽층 계면에서 III족 원소인 In, Al 및 Ga의 상호확산과 결함이 완화되는 현상으로 해석할 수 있다.

• Journal of Radiation Protection and Research
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• v.1 no.1
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• pp.22-30
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• 1976

The perturbation of dose distribution adjacent to cavities in high energy electron has shown that the percentage of dose increase varies markedly as a function of the build-up layer, the length and thickness of the cavities, and the electron energy. The dose distribution showed that cavities similar in size to those encountered in the head and neck measured by industrial film dosimetry and corrected by ionization chambers. The most increased doses by measuring are resulted in a localized dose of up to 130% of that measured at the depth of maximum dose within a homogeneous tissue equivalent phantom. The measured values and correction factors of dose perturbation due to air cavities showed in diagrams and would be summarized as follows. 1. In $8{\sim}12MeV$ electron beams, the most marked dose is observed when the build-up layer thickness is 0.5cm and cavity volume is $2{\times}2{\times}2cm^3$. 2. The highest dose point is located under cavity when the energy is increased and cavity length is longer. 3. The cavity length at which the maximum percentage dose occurs decreases with increasing energy. 4. The highest percentage cavity doses are obtained when the energy is high, the build-up layer is thin, the thickness of the cavity is large, and the length of the cavity is approximately 1 to 3cm. 5. The doses of upper portion of cavity are less than the standard dose distribution as 5 to 10%. 6. The maximum range of electron beam are extended as much as thickness of cavity. 7. A cavity having a length of 5cm closely approximates a cavity of infinite length.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1581-1586
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• 2006

A La (III) ion-selective membrane sensor has been fabricated from poly vinyl chloride (PVC) matrix membrane, containing 3-hydroxy-N'-(pyridin-2-ylmethylene)-2-naphthohydrazide (HPMN) as a neutral carrier, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as an anionic excluder and ortho-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of membrane composition and pH as well as the influence of the anionic additive on the response properties were investigated. The sensor with 30% PVC, 62% solvent mediator, 6% ionophore and 2% anionic additive, shows the best potentiometric response characteristics. It displays a Nernstian behavior (19.2 mV per decade) across the range of $1.0{\times}10^{-2}-1.0{\times}10^{-7}$ M. The detection limit of the electrode is $7.0{\times}10^{-8}$ M ($\sim$10 ng/mL) and the response time is 15 s from $1.0{\times}10^{-2}$ up to $1.0{\times}10^{-4} $M and 30 s in the range of $1.0 {\times}10^{-5}-1.0{\times}10^{-7}$ M. The sensor can be used in the pH values of 3.0-9.0 for about seven weeks. The membrane sensor was used as an indicator electrode in the potentiometric titration of lanthanum ions with EDTA. It was successfully applied to the lanthanum determination in some mouth wash preparations.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.49.2-49.2
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• 2009

투명전극은 디스플레이, 태양전지와 같은 광전자 소자에 필수적이며, 지금까지 개발된 재료 중에는 ITO가 가장 투명하면서 전기전도도가 높고 생산성도 좋기 때문에 투명전극의 재료로 사용하고 있다. ITO는 낮은 비저항(${\sim}10^{-4}{\Omega}cm$) 과 높은 투과율 (~85 %), 상대적으로 넓은 밴드갭 에너지 (3.5 eV) 의특성과 같이 뛰어난 전기적 광학적 특성에 반해서 높은 원자재 가격, 불안정한 공급량 등으로 인한 문제점이꾸준히 제기되고 있다. 따라서 $In_2O_3$:Sn, ZnO:Al, ZnO:Ga, ZnO:F, ZnO:B, TiN 등과 같은 물질들로대체하려는 연구가 활발하게 진행되고 있다. ZnO는 ITO보다원자재의 수급이 원활하기 때문에 원가가 낮으며, 상대적으로 낮은 온도에서도 제작이 가능하다. 또한 화학적으로 안정적이므로 ZnO에 Al, Ga 등의 3족 원소를 도핑함으로써 낮은 비저항의 박막 제작이 가능하고, ITO 박막과 비교하여 etching이 쉬우며 기판과의 접착성이 좋으며, sputtering 공정시 plasma 분위기에서의 안정성이 뛰어나고 박막증착율이 높기 때문에 투명전극으로 적합한 재료이다. 본 연구에서는 cylindrical type의 Aldoping된 ZnO single target을 사용하여 박막 증착 압력의 변화를 주어 유리기판 위에 DC sputtering을 하였다. Fieldemission scanning electron microscope (FESEM)을 통해 ZnO:Al 박막의 표면의 형상과 두께를 확인하였으며, X-ray diffraction (XRD) 분석을 통해 박막의 결정학적 특성을 관찰하였다. 투명전극용 물질로서 ZnO:Al 박막의 적합성 여부를 확인하기 위하여 Van der Pauw 방법을 이용하여 박막의 비저항, 전자 이동도, 캐리어 농도를 측정하였으며, 박막의 기계적 성질 및 표면 접착성을 확인하기 위하여 nano-indentaion 분석을 하였다. 또한 UV-vis spectrophotometer를 이용하여 ZnO:Al 박막의 투과율을 분석하여 투명전극으로의 응용 가능성을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.131-131
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• 2009

Silicon Carbide (SiC) is a material with a wide bandgap (3.26eV), a high critical electric field (~2.3MV/cm), a and a high bulk electron mobility ($\sim900cm^2/Vs$). These electronic properties allow high breakdown voltage, high-speed switching capability, and high temperature operation compared to Si devices. Although various SiC DMOSFET structures have been reported so far for optimizing performances, the effect of channel dimension on the switching performance of SiC DMOSFETs has not been extensively examined. This paper studies different channel dimensons ($L_{CH}$ : $0.5{\mu}m$, $1\;{\mu}m$, $1.5\;{\mu}m$) and their effect on the the device transient characteristics. The key design parameters for SiC DMOSFETs have been optimized and a physics-based two-dimensional (2-D) mixed device and circuit simulator by Silvaco Inc. has been used to understand the relationship. with the switching characteristics. To investigate transient characteristic of the device, mixed-mode simulation has been performed, where the solution of the basic transport equations for the 2-D device structures is directly embedded into the solution procedure for the circuit equations. We observe an increase in the turn-on and turn-off time with increasing the channel length. The switching time in 4H-SiC DMOSFETs have been found to be seriously affected by the various intrinsic parasitic components, such as gate-source capacitance and channel resistance. The intrinsic parasitic components relate to the delay time required for the carrier transit from source to drain. Therefore, improvement of switching speed in 4H-SiC DMOSFETs is essential to reduce the gate-source capacitance and channel resistance.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.2
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• pp.253-263
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• 2008

This study examined the menu management and utilization of cooking equipment at school foodservice operations in the Chonbuk area. Self-administered questionnaires were collected from a total of 193 school dietitians. Statistical data analysis was completed using the SPSS v. 11.5 program. The results are summarized as follows. Among the 193 schools, 58.5% were elementary schools and 41.5% were middle and high schools. Approximately 97% of the schools prepared meals in the conventional manner. Among the school, 68.4% had a menu cycle of 1${\sim}$2 weeks. The frequency of using convenience foods was significantly different between the elementary schools and middle and high schools(p<0.001). Approximately 45% of the dietitians responded that the most important details for menu planning were menu variety and consumer preference. However, 66.8% of the dietitians responded that a key problem for menu planning was limited and worn-out kitchen equipment. Although the cost of purchasing cooking equipment is high, most dietitians responded they have high needs for equipment in order to meet of the quantity demands of food production. In terms of utilized cooking equipment, most schools had mixers, vegetable cutters, choppers, dish washers, etc. Yet the amenities most often lacking were meat slicers, composting machines, ovens, and griddles. In utilizing the cooking equipment, there was no significant difference between the dietitians in the elementary(3.67) schools and those in the middle and high school foodservice systems(3.70); however, the utilization level was poor. Therefore, governmental regulatory agencies should review and finance support for purchasing cooking equipment. Finally, purchasing analysis was conducted regarding the dietitians' opinions on menu recipes and useful equipment.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.2
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• pp.101-110
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• 2004

Voltage-sensitive release mechanism was pharmacologically dissected from the $Ca^{2+}-induced\;Ca^{2+}\;release$ in the SR $Ca^{2+}$ release in the rat ventricular myocytes patch-clamped in a whole-cell mode. SR $Ca^{2+}$ release process was monitored by using forward-mode $Na^+-Ca^{2+}$ exchange after restriction of the interactions between $Ca^{2+}$ from SR and $Na^+-Ca^{2+}$ exchange within micro-domains with heavy cytosolic $Ca^{2+}$ buffering with 10 mM BAPTA. During stimulation every 10 s with a pulse roughly mimicking action potential, the initial outward current gradually turned into a huge inward current of $-12.9{\pm}0.5\;pA/pF$. From the inward current, two different inward $I_{NCX}s$ were identified. One was $10\;{\mu}M$ ryanodine-sensitive, constituting $14.2{\pm}2.3%$. It was completely blocked by $CdCl_2$ (0.1 mM and 0.5 mM) and by $Na^+-depletion$. The other was identified by 5 mM $NiCl_2$ after suppression of $I_{CaL}$ and ryanodine receptor, constituting $14.8{\pm}1.6%$. This latter was blocked by either 10 mM caffeine-induced SR $Ca^{2+}-depletion$ or 1 mM tetracaine. IV-relationships illustrated that the latter was activated until the peak in $30{\sim}35\;mV$ lower voltages than the former. Overall, it was concluded that the SR $Ca^{2+}$ release process in the rat ventricular myocytes is mediated by the voltage-sensitive release mechanism in addition to the $Ca^{2+}-induced-Ca^{2+}\;release$.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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• pp.809-816
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• 1997

The present study was designed to investigate whether endogenous nitric oxide(EDNO) is involved in submandibular vasodilation and salivation induced by parasympathetic nerve stimulation. Effects of $N^w$-nitro-L-arginine-methyl ester (L-NAME) which blocks the synthesis of EDNO from L-arginine on the submandibular vasodilation and salivation induced by chords stimulation or administration of various vasodilators were examined in anesthetized cats. Effect of L-NAME on $K^+$ efflux induced by carbachol was also examined using the excised submandibular slice in vitro. In the submandibular slices, acetylcholine$(10^{-5}\;mol/L)$ or vasoactive intestinal polypeptide$(VIP,\;10^{-5}\;mol/L)$ increased $NO_2$ contents, which was Prevented by pretreatment with L-NAME. Salivary secretion in response to the chords stimulation$(3\;V,\;1\;msec,\;10{\sim}20\;Hz)$ was completely blocked by treatment with atropine(1 mg/kg). Increased blood flow response to the low frequency(1, 2, 5 Hz) stimulation was significantly reduced, whereas the blood flow induced by the higher frequency(10,20 Hz) stimulation was not affected. Lingual-arterial infusion of L-NAME(100 mg/kg) significantly diminished the vasodilatory and salivary responses to the chorda stimulation at all stimuli frequencies used. Intra-arterial infusion of L-NAME(100 mg/kg markedly diminished the vasodilatory responses to acetylcholine$(5\;{\mu}g/kg)$, VIP$(5\;{\mu}g/kg)$ or bradykinin$(5\;{\mu}g/kg)$. In the excised submandibular slice, $K^+$ efflux in response to carbachol$(10^{-5}\;mol/L)$ was significantly decrease by pretreatment with L-NAME$(10^{-5}\;mol/L)$. In the isolated submandibular artery precontracted with phenylephrine$(10^{-5}\;mol/L)$, the vasorelaxation induced by ACh$(10^{-7}\;mol/L)$ was reversed into a contraction by methylene blue$(10^{-4}\;mol/L)$. These results suggest that EDNO may play an important role in vasodilation and secretion of the submandibular gland.

• Journal of radiological science and technology
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• v.16 no.1
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• pp.57-65
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• 1993

Asymetric system have been introduced in these years by KODAK company nam of Insight system for the purpose of improve the chest image. We have had a problem of chest radiology that it is very difficult to visualize the lung field and modiastinal region at one shot. That's why we are the RT using the technique of high voltage hard quality radiography in chest radiography. Also it is known the c-type wide latitude film can lift up the density of mediastinal structures. Authors investigated the photographic characteristics and physical structure of Insight system. Method 1. Investigated the structure of Emulsion layer. Calculated the particle size of Insight system using SEM(Scanning Electron Microscope). 2. Photographic characteristics has been compared the Insight system with the ortho KM/MG combination in $60{\sim}120kV$ range. Results 1. The particle size of backside film were investigated about 2 times larger that of front side film. 2. The front and backscreen's thickness ratio was detected 1 : 3.87, that the backscreen's thickness was thicker than frontscreen. 3. At the view point of photographic characteristics the frontside of insight system make up the contrast, backside make up the density at low exposure lesion.

• Applied Biological Chemistry
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• v.33 no.4
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• pp.287-292
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• 1990

Eight(I through VII) of Bowman-Birk proteinase inhibitor have been isolated from soybean with DEAE-Sephadex A-50. Inhibitor VII was a typical BBTI, showing high cysteine content(17%/mole) ud low trypsin to chymotrypsin inhibiting activity(TIA/CIA= 1.0) with the independent reactive site to each enzyme. Dissociation constant of trypsin-BBTI and chymotrypsin-BBTl complexes were $9.17{\times}10^{-9}M$ and $5.14{\times}10^{-8}M$, respectively. Inhibitor Vll was extremely heat stable. Six hours heat treatment at $100^{\circ}C$ caused only 50% decrease in it's original inhibiting activity. Except inhibitor III,6 other isoinhibitors differed from a typical BBTI in TIA/CIA, values, ranging from 3 to 29.