• Journal of the Korean Institute of Telematics and Electronics
• /
• v.20 no.1
• /
• pp.45-49
• /
• 1983

The four-layered(metal/insulator/n epi-layer/p+) controlled inversion devices have been fabricated. The I-V curve showed two characteristic states―an On state and an OFF state which were separated by a negative resistance region. The switching voltage and the holding voltage were about 5.0V and 2.5V, respectively. The switching voltage of the device was decreased by photo illumination while the holding voltage remained unaffected.

• Communications of the Korean Mathematical Society
• /
• v.26 no.2
• /
• pp.305-320
• /
• 2011

The relations among various types of continuity of fuzzy proper function on a fuzzy set and at fuzzy point belonging to the fuzzy set in the context of $\v{S}$ostak's I-fuzzy topological spaces are discussed. The projection maps are defined as fuzzy proper functions and their properties are proved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.11a
• /
• pp.295-299
• /
• 1996

In order to investigate the relation between the microstructure and the V-I characteristics of HTSC wire, single and 19 filamentary silver-sheathed Bi2223 tapes were fabricated using the powder-in-tube method. Higher J$\_$c/ at 77.3 K(0 T) and 4.2 K(in magnetic field) can be achieved for the 19 filamentary Bi tape, comparing the single filamentary tape. However, the I$\_$c/ distribution of 19 filamentary Bi2223 tape was found to be wider by analyzing the curve obtained from 2nd differential of V-I data. This was considered to be resulted from worse uniformity of oxide filament due to severe cold working.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.3
• /
• pp.569-575
• /
• 2020

Recently, research on renewable energy technologies has come into the spotlight due to rising concerns over the depletion of fossil fuels and greenhouse gas emissions. Demand for portable electronic and wearable devices is increasing, and electronic devices are becoming smaller. Energy harvesting is a technology for overcoming limitations such as battery size and usage time. In this paper, the V-I characteristic curve and internal resistance of thermal electric devices were analyzed, and MPPT control methods were compared. The Perturbation and Observation (P&O) control method is economically inefficient because two sensors are required to measure the voltage and current of a Thermoelectric Generator(TEG). Therefore, this paper proposes a new MPPT control method that tracks MPP using only one sensor for the regulation of the output voltage. The proposed MPPT control method uses the relationship between the output voltage of the load and the duty ratio. Control is done by periodically sampling the output voltage of the DC-DC converter to increase or decrease the duty ratio to find the optimal duty ratio and maintain the MPP. A DC-DC converter was designed using a cascaded boost-buck converter, which has a two-switch topology. The proposed MPPT control method was verified by simulations using PSIM, and the results show that a voltage, current, and power of V=4.2 V, I=2.5 A, and P=10.5 W were obtained at the MPP from the V-I characteristic curve of the TEG.

• Herbal Formula Science
• /
• v.12 no.1
• /
• pp.209-223
• /
• 2004

Objective: This study was conducted to investigate the effects of Coptidis Rhizoma on the plasma IL-6 and $TNF-{\alpha}$ level in mice by intracerebroventricular(I.C.V.) injection of Lipopolysaccharide (LPS). Method: 6 mice were assigned to each of the Normal group, the Control group, and the individual Experimental groups. In the Normal group only saline was administered intragastrically, and in the Control group LPS was injected intracerebroventricularly 1 hr after intragastric administration of saline. In the Experimental groups Coptidis Rhizoma(0.5g/kg, 1.0g/kg, 3.0g/kg) was administered intragastrically to mice 1 hr prior to LPS (100ng/mouse) I.C.V. Injection. To measure the plasma IL-6 and $TNF-{\alpha}$ level of mice, their blood samples were collected from retro-orbital venous plexus, immediately centrifuged at $4^{\circ}C$, and plasma was removed and stored frozen at $-83^{\circ}C$ for later determination of plasma IL-6 and $TNF-{\alpha}$. Result: 1. LPS I.C.V. Injection increased plasma IL-6 level significantly in a dose-dependent manner compared with Normal group. (P<0.01) The plasma IL-6 concentration reached a significant maximal level about 1 hr after LPS(100ng/mouse) I.C.V. Injection.(P<0.001) 2. Both the 0.5g/kg(Sample A) and 1.0g/kg(Sample B) groups to which Coptidis Rhizoma was administered intragastrically 1 hr prior to LPS(100ng/mouse) I.C.V. Injection showed insignificant lower plama IL-6 level in 1 hr than Control group(P>0.05), and 3.0g/kg group(Sample C) conversely showed higher plama IL-6 level than Control group. 3. LPS I.C.V. Injection increased plasma $TNF-{\alpha}$ level significantly in a dose-dependent manner compared with Normal group.(P<0.05) The plasma $TNF-{\alpha}$ concentration reached a significant maximal level about 1 hr after LPS(100ng/mouse) I.C.V. Injection.(P<0.001) 4. All Sample groups(0.5g/kg, 1.0g/kg, and 3.0g/kg) to which Coptidis Rhizoma was administered intragastrically with each constituent-dose 1 hr prior to LPS(100ng/mouse) I.C.V. Injection showed significant lower $TNF-{\alpha}$ plama level in 1 hr than Control group.(P<0.001) These data revealed that Coptidis Rhizoma might have anti inflammatory effect by reducing the plasma $TNF-{\alpha}$ level in a dose dependent manner in mice LPS I.C.V. Injection.

• Herbal Formula Science
• /
• v.12 no.1
• /
• pp.195-208
• /
• 2004

Objective: This study was conducted to investigate the effects of Aconiti Tuber on the plasma IL-6 and $TNF-{\alpha}$ level in mice stimulated by intracerebroventricular(I.C.V.) Injection of Lipopolysaccharide(LPS). Method: 6 mice were assigned to each of the normal group, the control group, and the experimental group. In the normal group only saline was administered intragastrically, and in the control group LPS was injected intracerebro-ventricularly 1 hr after intragastric administration of saline. In the experimental groups (Aconiti Tuber 0.5g/kg, Aconiti Tuber 1.0g/kg, Aconiti Tuber 3.0g/kg) each sample was administered intragastrically to mice 1 hr prior to the stimulation by LPS I.C.V. Injection. To measure the plasma IL-6 and $TNF-{\alpha}$ level of mice, their blood samples were collected from retro-orbital plexus, immediately centrifuged at $4^{\circ}C$, and plasma was removed and stored frozen at $-83^{\circ}C$ for later determination of plasma IL-6 and $TNF-{\alpha}$. Result : 1. LPS I.C.V. Injection increased plasma IL-6 level significantly in a dose-dependent manner compared with normal group(P<0.01). The plasma IL-6 concentration reached a significant maximal level about 1 hr after LPS I.C.V. Injection(P<0.001). LPS I.C.V. Injection increased plasma $TNF-{\alpha}$ level significantly in a dose-dependent manner(P<0.05). The plasma $TNF-{\alpha}$ concentration reached a significant maximal level about 1 hr after LPS I.C.V. Injection(P<0.001). 2. Sample A group to which Aconiti Tuber(0.5g/kg) was administered intragastrically 1 hr prior to the stimulation by LPS I.C.V. Injection showed insignificant lower plasma IL-6 level in 1 hr than control group(P<0.0635), and sample B group (Aconiti Tuber 1.0g/kg) showed significant lower plasma IL-6 level in 1 hr than control group(P〈0.05), and sample C group (Aconiti Tuber 3.0g/kg) showed significant lower IL-6 plasma level in 1 hr than control group(P<0.01). 3. sample A group to which Aconiti Tuber(0.5g/kg) was administered intragastrically 1 hr prior to the stimulation by LPS I.C.V. Injection showed insignificant lower plasma $TNF-{\alpha}$ level in 1 hr than control group(P>0.05), and Both sample B(1.0g/kg) and sample C(3.0g/kg) groups showed significant lower $TNF-{\alpha}$ plasma level in 1 hr than control group(P<0.01). These data revealed that Aconiti Tuber might have the anti inflammatory effect by reducing the plasma IL-6 and $TNF-{\alpha}$ level in a dose dependent manner in mice LPS I.C.V. Injection.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.3
• /
• pp.147-151
• /
• 2016

Graphene has a monolayer crystal structure formed with C-atoms and has been used as a base layer of HETs (hot electron transistors). Graphene HETs have exhibited the operation at THz frequencies and higher current on/off ratio than that of Graphene FETs. In this article, we report on the preliminary results of current characteristics from the HETs which are fabricated utilizing highly doped Si collector, graphene base, and 5 nm thin $Al_2O_3$ tunnel layers between the base and Ti emitter. We have observed E-B forward currents are inherited to tunneling through $Al_2O_3$ layers, but have not noticed the Schottky barrier blocking effect on B-C forward current at the base/collector interface. At the common-emitter configuration, under a constant $V_{BE}$ between 0~1.2V, $I_C$ has increased linearly with $V_{CE}$ for $V_{CE}$ < $V_{BE}$ indicating the saturation region. As the $V_{CE}$ increases further, a plateau of $I_C$ vs. $V_{CE}$ has appeared slightly at $V_{CE}{\simeq}V_{BE}$, denoting forward-active region. With further increase of $V_{CE}$, $I_C$ has kept increasing probably due to tunneling through thin Schottky barrier between B/C. Thus the current on/off ration has exhibited to be 50. To improve hot electron effects, we propose the usage of low doped Si substrate, insertion of barrier layer between B/C, or substrates with low electron affinity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.31 no.3
• /
• pp.135-140
• /
• 2018

Atomically thin $MoS_2$ single crystals have a two-dimensional structure and exhibit semiconductor properties, and have therefore recently been utilized in electronic devices and circuits. In this study, we have fabricated a field effect transistor (FET), using a CVD-grown, 3 nm-thin, $MoS_2$ single-crystal as a transistor channel after transfer onto a $SiO_2/Si$ substrate. The $MoS_2$ FETs displayed n-channel characteristics with an electron mobility of $0.05cm^2/V-sec$, and a current on/off ratio of $I_{ON}/I_{OFF}{\simeq}5{\times}10^4$. Application of bottom-gate voltage stresses, however, increased the interface charges on $MoS_2/SiO_2$, incurred the threshold voltage change, and degraded the device performance in further measurements. Exposure of the channel to UV radiation further degraded the device properties.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.12 no.4
• /
• pp.253-259
• /
• 1992

The esterase isozyme in tissue of wild legume plants were separated by horizontal starch gel electrophoresis. Extracts used in this study were prepared from fully expanded young leaf, cotyledon and radicle of seedling and root-nodule of Glycine sola, Vigna vexillata var. tsuscmensis and Trifoliwn repens. The results are as follows; 1. Each tissue examined had a characteristic banding pattcrn. Number of bands in each species, G. soja, V. vexillata, and T . repens, were 14, 8 and 1 1 bands, respectively. And difference in esterase isozyme bands were greater from tissue to tissue than difference between habitat. 2. Est-I, Est-2. Est-3 and Est-4 in G. soja, Est-I in V. vexillata and Est-l and Est-2 in T. repens showed strong cnzyme activity than other enzyme. 3. Esterase isozyme variation in G. soja and T . repens showed more variety than V. vexillata. This is resulted from many genotypic differences within species. 4. The main enLyme among thc esterase isozyme were Est-I. Est-2, Est-3 and Est-4.

• Clinical and Experimental Reproductive Medicine
• /
• v.49 no.1
• /
• pp.62-69
• /
• 2022

Objective: This study aimed to describe a distinct subpopulation of azoospermic patients with isolated elevation of follicle-stimulating hormone (iFSH) and poor outcomes of microdissection testicular sperm extraction (microTESE). Methods: A retrospective analysis of microTESE outcomes was conducted among 565 patients with non-obstructive azoospermia (NOA). Testicular pathology was assessed by the dominant histological pattern and Bergmann-Kliesch score (BKS). Descriptive statistics were presented for the iFSH subgroup. Inhibin B levels, the sperm retrieval rate (SRR), and BKS were compared in iFSH patients and other NOA patients. Results: The overall SRR was 33.3% per microTESE attempt. The median BKS was 0.6 (interquartile range, 0-2). Of all NOA patients, 132 had iFSH, and microTESE was successful only in 11 of those cases, with an SRR of 8.3%, while the total SRR in other NOA patients was 38.1% (p<0.001). iFSH had a sensitivity of 32.1% (95% confidence interval [CI], 27.4%-36.8%) and specificity of 94.1% (95% CI, 90.8-97.5%) as a predictor of negative microTESE outcomes. Conclusion: Patients with iFSH may harbor a distinct testicular phenotype with total loss of the germ cell population and poor outcomes of surgical sperm retrieval.