• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.167-168
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• 2006

High quality 3D-heterostructures were constructed by selective area (SA) molecular beam epitaxy (MBE) using a specially patterned GaAs (001) substrate. MBE growth parameters such as substrate temperature, V/III ratio, growth ratio, group V sources ($As_2$, $As_4$) were varied to calibrate the selective area growth conditions. Scanning micro-photoluminescence ($\mu$-PL) measurements and following analysis revealed that the gradually (adiabatically) coupled 2DEG-1D-1DEG field effect transistor (FET) system was realized. This 3D-heterostructure is very promising for the realization of the meso-scopic electronic devices and circuits since it makes it possible to form direct ohmic contact to the (quasi) 1DEG.

• The Korean Journal of Food And Nutrition
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• v.17 no.3
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• pp.294-301
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• 2004

Effects of superoxide dismutase(SOD), catalase(CAT), and such other proteins as bovine serum albumin(BSA), ovalbumin, lysozyme, and v-globulin on the autoxidation rates of L-ascorbic acid(AsA) in the absence of heavy metal ions and in the presence of Fe(III) or Cu(II) ions in water were examined. AsA was dissolved in a ultra-refined water at a concentration of 50 ${\mu}$M and 5 ${\mu}$M Fe(III) or 0.1 ${\mu}$M Cu(II) were added, and a oxygen gas was bubbled through the solution at a flow rate of 200 ml/min at 35$^{\circ}C$. The amount of remaining AsA in the reaction mixture was determined by using a UV spectrophotometer(at 265 nm). It was found that the Cu(II) at a concentration of 0.1 ${\mu}$M had a more accelerated for the autoxidation of AsA than Fe(III) at 5 ${\mu}$M. Moreover, it was confirmed that the ratio of remaining AsA was significantly larger in the presence of SOD, CAT, BSA, ovalbumin, lysozyme, and v-globulin than in the absence of proteins. The stabilization of AsA by various proteins were confirmed during the autoxidation of AsA in the presence of Fe(III) or Cu(II) in water. It was suggested that the non-enzymatic effects of SOD, CAT and some other proteins might be involves in the stabilization of AsA.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.63-68
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• 2003

The purpose of this study was to investigate reduction of exhaust gas temperature in LPG conversion engine from diesel. A conventional diesel engine was modified to a LPG(Liquified Petroleum Gas) engine that diesel fuel injection pump was replaced by the LPG fuel system. The research was peformed with measurement of exhaust gas temperature by varying spark ignition timing, air-fuel ratio, compression ratio, EGR ratio and different compositions of butane and propane. The major conclusion of this work were followed. (i) Exhaust gas temperature was decreased and power was increased with the advanced spark ignition timing. (ii) Exhaust gas temperature was decreased with lean and rich air-fuel ratio. (iii)Exhaust gas temperature was decreased and power was increased with the higher compression ratio. (iv) Engine power and exhaust temperature were not influenced by varied butane/propane fuel compositions. (v) Finally, one of the important parameters in reduction of exhaust gas temperature is spark ignition timing among the parameters in this study.

• Structural Engineering and Mechanics
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• v.31 no.2
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• pp.225-235
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• 2009

The present paper reviews the shear design (of reinforced concrete beam) provisions of four different national codes and proposes a new but simplified shear strength empirical expression, incorporating variables such as compressive strength of concrete, percentage of longitudinal and vertical steel/s, depth of beam in terms of shear span-to-depth ratio, for reinforced concrete (RC) beams without shear reinforcement. The expression is based on the experimental investigation on RC beams without shear reinforcement. Further, the comparisons of shear design provisions of four National codes viz.: (i) IS 456-2000, (iii) BS 8110-1997, (iv) ACI 318-2002 (v) EuroCode-2-2002 and the proposed expression for the prediction of shear capacity of normal beam/s, have been made by solving a numerical example. The results of the numerical example worked out suggest that there is need for revision in the shear design procedure of different codes. Also, the proposed expression is less conservative among the IS, BS & Eurocode.

• Journal of Audiology & Otology
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• v.24 no.1
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• pp.10-16
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• 2020

Background and Objectives:The blockage of adenosine receptors by caffeine changes the levels of neurotransmitters. These receptors are present in all parts of the body, including the auditory and vestibular systems. This study aimed to evaluate the effect of caffeine on evoked potentials using auditory brainstem responses (ABRs) and cervical vestibular-evoked myogenic potentials (cVEMPs) in a double-blind placebo-controlled study. Subjects and Methods: Forty individuals (20 females and 20 males; aged 18-25 years) were randomly assigned to two groups: the test group (consuming 3 mg/kg pure caffeine powder with little sugar and dry milk in 100 mL of water), and the placebo group (consuming only sugar and dry milk in 100 mL water as placebo). The cVEMPs and ABRs were recorded before and after caffeine or placebo intake. Results: A significant difference was observed in the absolute latencies of I and III (p<0.010), and V (p<0.001) and in the inter-peak latencies of III-V and I-V (p<0.001) of ABRs wave. In contrast, no significant difference was found in cVEMP parameters (P13 and N23 latency, threshold, P13-N23 amplitude, and amplitude ratio). The mean amplitudes of P13-N23 showed an increase after caffeine ingestion. However, this was not significant compared with the placebo group (p>0.050). Conclusions: It seems that the extent of caffeine's effects varies for differently evoked potentials. Latency reduction in ABRs indicates that caffeine improves transmission in the central brain auditory pathways. However, different effects of caffeine on auditory- and vestibular-evoked potentials could be attributed to the differences in sensitivities of the ABR and cVEMP tests.

• Korean Journal of Audiology
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• v.24 no.1
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• pp.10-16
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• 2020

Background and Objectives:The blockage of adenosine receptors by caffeine changes the levels of neurotransmitters. These receptors are present in all parts of the body, including the auditory and vestibular systems. This study aimed to evaluate the effect of caffeine on evoked potentials using auditory brainstem responses (ABRs) and cervical vestibular-evoked myogenic potentials (cVEMPs) in a double-blind placebo-controlled study. Subjects and Methods: Forty individuals (20 females and 20 males; aged 18-25 years) were randomly assigned to two groups: the test group (consuming 3 mg/kg pure caffeine powder with little sugar and dry milk in 100 mL of water), and the placebo group (consuming only sugar and dry milk in 100 mL water as placebo). The cVEMPs and ABRs were recorded before and after caffeine or placebo intake. Results: A significant difference was observed in the absolute latencies of I and III (p<0.010), and V (p<0.001) and in the inter-peak latencies of III-V and I-V (p<0.001) of ABRs wave. In contrast, no significant difference was found in cVEMP parameters (P13 and N23 latency, threshold, P13-N23 amplitude, and amplitude ratio). The mean amplitudes of P13-N23 showed an increase after caffeine ingestion. However, this was not significant compared with the placebo group (p>0.050). Conclusions: It seems that the extent of caffeine's effects varies for differently evoked potentials. Latency reduction in ABRs indicates that caffeine improves transmission in the central brain auditory pathways. However, different effects of caffeine on auditory- and vestibular-evoked potentials could be attributed to the differences in sensitivities of the ABR and cVEMP tests.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.1
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• pp.68-76
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• 2017

Antioxidative capacities of Stachys sieboldii MIQ and 6-year-old ginseng powder were assessed after extraction with 80% ethanol, and their addition effects on quality characteristics of cookies were determined. Stachys sieboldii MIQ showed 3.12-fold higher total phenol content (TPC) and higher antioxidative capacities than ginseng based on higher values of 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity, ferric reducing antioxidant capacity, and Trolox equivalent antioxidant capacity (P<0.05). The 80% ethanol extract was then fractionated with $H_2O$ (Fr. I), 30% (II), 50% (III), 70% (IV), and 100% ethanol (V). Fractions of Stachys sieboldii MIQ extract showed 2.2-fold (Fr. I)~6.1-fold (III) higher TPC and higher antioxidative capacities than ginseng extract fractions. TPC was in the order of fractions III> II> I> IV> V for Stachys sieboldii MIQ extract while in the order of fractions I~III> IV~V for ginseng extract, assuming that Stachys sieboldii MIQ contained more phenolic compounds with higher polarity than ginseng. Addition of 5% and 10% Stachys sieboldii MIQ and ginseng powder increased spread ratio in cookies compared to 100% wheat flour, and 10% addition of Stachys sieboldii MIQ resulted in the darkest and most reddish cookies. In the sensory evaluation, cookies with 5% and 10% Stachys sieboldii MIQ received higher scores for taste preference and higher overall acceptability than ginseng or control cookies. Therefore, powder of Stachys sieboldii MIQ could impart more favorable sensory characteristics as well as higher antioxidative capacity than ginseng in bakery products.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.7 no.1
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• pp.71-78
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• 1969

To study the varietal differences of vegetative organs, yield and yield components along the periodical changes of rice variety in korea, this experiment was conducted in 1968. Eighteen used varieties were grouped into 6 varietal groups by the cultivated period as follow.: 1) Group I - Korean local varieties cultivated about 1907, 2) Group II - introduced varieties cultivated in 1907 - 1930, 3) Group III - introduced varieties cultivated in 1930-1960, 4) Group IV - improved varieties cultivated in 1930-1960, 5) Group V - introduced varieties cultivated after 1960 and 6) Group VI - improved varieties cultivated after 1960. 1. Varietal Group I showed the longest leaves, the largest leaf area, the lowest value of leaf area index and the highest value of flag leaf angle. Along the periodical changes of rice varieties the leaf length, the total leaf area and the flag leaf angle were decreased, and the leaf area index was increased. 2. Varietal Group I showed higher value of the length and the weight of leaf sheath than those of Group II, III, IV, V and VI. The length of every internode was longer in Group I than in the other varietal groups. The weight of every internode was shown higher value in Group 1. The length and the weight of every internode were decreased along the periodical changes of rice variety. 3. Varietal Group I and Group III showed the higher value of culm length, panicle length and the number of grain per panicle length and groups. Group IV, V and VI had the higher value of the number of panicle, the maturing rate and the 1, 000 grains weight. Varietal Group V and VI which are cultivated in recent years showed shorter culm and panicle length, higher value of the maturing rate and the 1, 000 grains weight, and intermediate in the number of panicle and the number of grain per panicle. 4. The lowest value of straw weight was found in Group I. The highest value of grain yield was shown in Group VI, intermediate in Group II, III, IV and V and lowest in Group I. Grain-straw ratio was shown highest in Group VI.

• Korean Journal of Environment and Ecology
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• v.27 no.5
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• pp.579-591
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• 2013

This study was carried out to investigate the actual vegetation, the structure of plant community, and ecological succession sere of forest ecosystem in temperate northern climate zone, Daegwallyeong Ranch, Gangwon-do (Province) and to offer the basic data for planning of the forest managemant. As a result of analysis of actual vegetation, vegetation types divided into 56types and the area of survey site was $19,397,361m^2$. The ratio of vegetation type dominated by Quercus mongolica forest was 39.1%, primary grassland was 24.7%, Quercus mongolica-Deciduous broad-leaved forest was 11.3%. Twenty eight plots (size is $20m{\times}20m$) were set up and the results analyzed by DCA which in one of the ordination technique showed that the plant communities were divided into six groups which area community I (Pinus densiflora-Quercus mongolica community), community II (Quercus mongolica-Pinus densiflora community), community III (Quercus mongolica community), community IV (Quercus mongolica-Deciduous broad-leaved community), community V (Deciduous broad-leaved community), community VI (Sorbus alnifolia community). The age of community Iwas ranged from 57 to 62 years old, that of community IIwas ranged from 41 to 77 years old, community III was ranged from 47 to 108 years old, community IV was ranged from 47 to 82 years old, community V was 47 years old, community VI was 55 years old, thus we supposed that the age of the study site is about from 41 to 108 years old. The Ecological succession is predicted from Pinus densiflora community to Quercus mongolica community and Deciduous broad-leaved were distributed in the center of the valley in Daegwallyeong Ranch. According to the index of Shannon's diversity (unit: $400m^2$), community IV was ranged from 0.8203 to 1.1439, community III was ranged from 0.8019 to 1.1375, community V was 1.0993, community I was ranged from 0.9475 to 1.0797, community II was ranged from 0.6896 to 1.0324, community VI was 0.9909.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.795-797
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• 1998

A $BaTiO_3$, ferroelectric material, was mixed $SrTiO_3$, $(x)BaTiO_3-(1-x)SrTiO_3$($0.7{\leq}x{\leq}1$) ceramic capacitor with stable electrical properties in high voltage was fabricated. And microstructure, electrical property were investigated with $SrTiO_3$ mol ratio. The shrinkage, open porosity, sintering density were predominated at $9BaTiO_3-0.1SrTiO_3$. Increasing $SrTiO_3$ mol ratio, curie temperature was shifted at low temperature and maximum permittivity was increased. Also, $0.9BaTiO_3-0.1SrTiO_3$ was showed stable dielectric properties at $25{\sim}80[^{\circ}C]$. V-I properties of specimen were observed in the temperature range of $21{\sim}143[^{\circ}C]$, were divided into three regions. The region I below 10[kV/cm] was shown Ohmic conduction, the region II from 10 to 30[kV/cm] was explained by the Poole-Frenkel emission theory and the region III above 30[kV/cm] was analysed by the tunneling effect.