• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.155-155
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• 2011

반도체 양자링은 양자점과 같이 효율이 높은 광학 소자 및 전자 소자에 응용 가능할 뿐 아니라, 양자점과는 다른 흥미로운 현상 연구가 가능하기 때문에 지속적으로 연구되고 있는 양자 구조이다. 특히, 반도체 양자링은 다양한 양자 구조를 형성하기 위한 기초 구조로 사용될 수 있으므로, 반도체 양자링 구조의 형성 메카니즘을 연구하는 것 또한 중요하다. 본 연구에서는 Molecular Beam Epitaxy (MBE)를 이용하여 N-type (100) GaAs 기판 위에 GaAs 양자 구조를 형성하였다. As4 분압의 영향, 즉 3-5 ratio가 표면 양자 구조 변화에 미치는 영향을 관찰하기 위해 3족과 5족을 분리하여 성장하는 전형적인 성장 방식인, droplet epitaxy mode를 사용하였다. 성장 온도, Ga metal droplet 밀도 등의 조건을 고정하고 Arsenic 분압을 1e-5 torr부터 3e-8 torr로 감소시켰을 때 표면 이미지를 AFM과 SEM으로 관찰하였다. As4 분압이 1e-5 torr일 때 양자점의 표면 형상을 보여주다가 As4 분압을 줄여갈수록 양자점의 크기가 증가하면서 As4 분압 1e-6 torr에서는 SEM 이미지 상으로도 분명한 양자링을 관찰할 수 있었다. 특히 주목할 것은 As4 분압 1e-6 torr에서 더 줄여갈수록 양자링 중앙 부분의 낮은 부분이 점점 넓어졌다는 점이다. 이것은 As4 분압 1e-6 torr 이상의 조건이 As4와 Ga atom이 결합하여 GaAs 양자점을 형성하는데 적절한 3-5 ratio의 조건인 반면, 그보다 적은 As4 분압에서는 As4와 결합하지 못한 Ga atom의 표면 migration에 의한 driving force로 인해 양자링이 형성되었다고 추측할 수 있다. 이렇게 형성된 양자링을 열처리 후 macro-PL 측정을 통해 광학적 특성을 보고자 하였다. 그 결과 같은 조건에서 열처리되어 PL 측정한 양자점의 에너지에 비해 peak position이 blue shift한 것을 볼 수 있었다. 이것은 As4를 제외한 같은 조건에서 성장된 양자 구조에서 양자링의 경우 양자점에 비해 그 높이가 낮음을 추측해 볼 수 있다. 양자 구조의 모양과 광학 특성의 관계를 밝히기 위해 추후 추가 측정 및 분석이 필요할 것이다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.2
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• pp.99-103
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• 2011

This study was performed to determine the optimal hydrolysis conditions for the production of a flavoring from the precipitation of snow crab cooker effluent (PSCCE) with commercial proteases. Based on cost-per-enzyme activity and sensory evaluations, Flavourzyme$^{(R)}$ 500 MG plus Protamex$^{(R)}$ (1:1 ratio, w/w) were selected as suitable enzymes. Three independent variables consisting of the substrate concentration (S), enzyme-to-substrate ratio (E/S), and hydrolysis time (T) were examined using response surface methodology (RSM). A model equation obtained from RSM was used to predict the degree of hydrolysis (DH) as follows: % DH = 52.285 - 6.371[S] + 5.469[E/S] + 7.599[T] - $5.818[S]^2$ - $5.633[E/S]^2$ - $6.528[T]^2$ - 3.265[E/S][S] - 5.415[T][S] + 4.315[T][E/S]. From the ridge analysis, the conditions favoring the highest degree of hydrolysis were pH 7.45, $55^{\circ}C$, a S of 21.82%, an E/S of 0.50%, and a T of 3.74 h.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.103-110
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• 2010

This paper addressed the implementation of the systematic performance analysis of Quality of Service (QoS) by using OPNET simulator in the interworking architecture of IEEE 802.16e (mobile WiMAX) and IEEE 802.11e (WLAN) wireless network. Four simulation cases were provided in OPNET simulator and a voice traffic was simulated with various performance metrics, such as Mean Opinion Score (MOS), end-to-end delay and packet transmission ratio. Based on the simulation results, the MOS value presented better in WiMAX to WiMAX case compared to others in both static and mobility case. Meanwhile, end-to-end delay was not greatly affected by mobility in four cases. However, mobility was affected much in MOS value and packet transmission ratio in WLAN to WLAN case than in others.

• Journal of Acupuncture Research
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• v.30 no.3
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• pp.15-25
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• 2013

Objectives : This study was designed to investigate the anti-obesity effects in local area adipose tissue using by pharmacopuncture of Eriobotryae Folium on mice fed high fat diet. Methods : Male ICR mouse were divided into three groups. Normal diet group (N), High-fat diet(HFD) group, HFD+E(pharmacopuncture of the Eriobotryae Folium) group for 8 weeks. HFD+E group was injected in the concentration of 50 mg/kg once a day for 4 weeks and every other day during the next 4 weeks. We measured body weight, food intake, absolute weight and relative weight in the liver and adipose tissue. Also, we analyzed hematological levels and histopathological changes on adipose tissue. Results : 1. We observed no difference in food intake among three groups. 2. HFD+E group significantly decreased body weight gain and absolute weight and relative weight in the liver and adipose tissue compared with HFD group. 3. Blood AST and ALT were no differences among the experiment groups. However, HFD group was significantly increased higher TG, TC, HDL and LDL than in N group and HDL/LDL ratio was remarkably decreased. On the other hand, HFD+E group was significantly decreased in obesity markers and HDL/LDL ratio was remarkably increased. 4. Levels of adiponectin in serum of HFD+E group was remarkably increased compared with those of HFD group. 5. HFD group was significantly decreased compared with N group in adipocyte number. Compared with the HFD group, HFD+E group was displayed a significant increase by adipocyte number. Conclusions : We suggest that pharmacopuncture of the Leaves of Eriobotrya japonica can play the anti-obesity effects in local area adipose tissue.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.219-225
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• 2007

The equilibrium solubilization capacity of pure hydrocarbon oils by 2.5 wt% $C_{12}E_8$ nonionic surfactant solution was measured at $30^{\circ}C$ by gas chromatography (GC) analysis. Experimental results indicated that the molar solubilization ratio (MSR) for pure alkanes was found to decrease almost linearly with the alkane carbon number (ACN) of the hydrocarbon oil. For the binary mixture systems of the hydrocarbon oils both selective and nonselective solubilization behaviors were observed depending on the difference in carbon number of the two hydrocarbon oils. Equilibrium solubilization tests for the two n-octane/n-nonane and n-nonane/n-decane mixture systems in $C_{12}E_8$ surfactant solutions suggest slightly selective solubilization in favor of n-octane, but the small difference in solubilization rates between two hydrocarbon oils does not allow ruling out non-selective solubilization for these particular systems. This is certainly not the case for the n-octane/n-decane mixture, for which selective solubilization was conclusively demonstrated by GC analysis data.

• Development and Reproduction
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• v.6 no.2
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• pp.105-110
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• 2002

Numerous hormones are involved in the regulation of reproduction. Among them, estrogen and progesterone are the most important ovarian steroid hormones regulating female fertility. On the other hand, diverse stressors impede female receptivity and fertility. Since norepinephrine(NE) and epinephrine(E) are released from the adrenal during stress, it might play a role in stress-induced disruptions of fEmale reproductive parameters. The present study was performed to analyze the changes in adrenal catecholaminergic activities in cycling rats. The tissue content and secretion level of catecholamines were determined by high performance liquid chromatography coupled with electrochemical detector(HPLC-ECD). Adrenomedullary content of norepinephrine(NE) was increased on proestrus stage (59.47 $\pm$ 6.86 ug/gland), peaked on diestrus I stage(65.22 $\pm$ 5.99 ug/gland), and was nadir on diestrus II stage(41.63 $\pm$ 1.33 ug/gland). The highest E content was observed on proestrus stage(361.86 $\pm$ 15.58 ug/gland) while the lowest level was on diestrus II stage(285.58 $\pm$ 12.25 ug/gland). In addition to these observations, a significant reduction of the NE : E ratio was observed (1 : 4.81 on diestrus I vs 1 : 6.13～7.02 on other stages). In vitro secretion of adrenal NE and E was increased on proestrus stage, peaked on estrus stage, and decreased on diestrus II stage. Interestingly, the NE : E ratio in conditioned media was significantly increased on estrus stage (1 : 3.32 vs 1 : 2.34～2.65 on other stages. The biosynthesis of NE and E is mediated by tyrosine hydroxylase(TH) and phenylethanolamine-N-methyltransferase(PNMT) which acts conversion of tyrosine into DOPA and NE into E, respectively. These finding demonstrated that sex steroids, during setrous cycle, seem to be able to modify the adrenal catecholamines biosynthesis and secretion with stage-specific manner by modulation of the enzyme activities.

• Journal of the Korean Ceramic Society
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• v.42 no.1
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• pp.16-21
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• 2005

The effect of additive composition, using AlN and $Er_{2}O_{3}$ as sintering additives, on the mechanical properties of liquid-phase-sintered, and subsequently annealed SiC ceramics was investigated. The microstructures developed were quantitatively analyzed by image analysis. The average thickness of SiC grains increased with increasing the $Er_{2}O_{3}/(AlN + Er_{2}O_{3})$ ratio in the additives whereas the aspect ratio decreased with increasing the ratio. The mechanical properties versus $Er_{2}O_{3}/(AlN + Er_{2}O_{3})$ ratio curve had a maximum; i.e., there was a small composition range at which optimum mechanical properties were realized. The best results were obtained when the ratio ranged from 0.4 to 0.6. The flexural strength and fracture toughness of the SiC ceramics were $550\~650\;MPa$ and $5.5\~6.5$ MPa${\cdot}m^{1/2}$, respectively.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.29-30
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• 2012

The objectives of this study are to examine the variation of flame chemiluminescence on flame condition and to evaluate the possibility to apply the optical sensor for air/fuel ratio control. Flame chemiluminescence is one of the most important factor to judge the real time flame condition like a air/fuel ratio. In this paper, it is experimentally found that a strong relationship between the air/fuel ratio and optical element output (i.e., photo diode) should be existed. This is verified through the flame spectral analysis for various PD output signal.

• Nuclear Engineering and Technology
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• v.46 no.6
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• pp.883-888
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• 2014

This work presents the influence of noise originating from the tube itself on the detectability and sizing accuracy for laboratory-induced outer diameter axial cracks in nuclear steam generator tubes. The variations of signal amplitude and phase angle of the same cracks were analyzed when increasing the signal-to-noise ratio of the tube itself from 9 to 18. It was experimentally verified that the detectability for small cracks was enhanced by increasing the signal-to-noise ratio. The phase angle also rotated to a value representing the actual position and depth of a crack when increasing the signal-to-noise ratio.

• Computers and Concrete
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• v.11 no.4
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• pp.291-304
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• 2013

By considering the creep characteristics of concrete core under eccentric compression, a creep model of concrete filled steel tubes (CFT) columns under eccentric compressive loads is proposed based on the concrete creep model B3. In this proposed model, a discrete element method is introduced to transform the eccentric loading into axial loading. The validity of the model is verified by comparing the predicting results with the published creep experiments results on CFT specimens under compressive loading, together with the predicting values based on other concrete creep models, such as ACI209, CEB90, GL2000 and elastic continuation and plastic flow theory. By using the proposed model, a parameters study is carried out to analysis the effects of practical design parameters, such as concrete mix (e.g. water to cement ratio, aggregate to cement ratio), steel ratio and eccentricity ratio, on the creep of CFT columns under eccentric compressive loading.