• Journal of the Korean Society for Precision Engineering
• /
• v.11 no.5
• /
• pp.33-41
• /
• 1994

For the establishment of large force standard and the accurate measurement of large force, 2MN hydraulic force standard machine which consists of loading frame, deadweight machine, two ram/cylinder systems and hydraulic control system was designed and fabricated. Measurement results of shapes for tow ram/cylinders reveal that the ratio of effective area is 200.094. The relative deviation of force stability for the machine is about .+-. 0.01% at 2MN and is less than .+-. 0.005% below 2MN. This machine may be widely used to calibrate the force measuring devices in industry and to test the force sensors.

• Journal of the Korean Chemical Society
• /
• v.41 no.3
• /
• pp.117-122
• /
• 1997

On the basis of our previous paper[Bull. Korean Chem. Soc. 1995, 16, 1015], the relative stability, ionization potential, and chemical reaction of the neutral and multiply charged $C_{60}$n ions(n=3+ to 6-) have been investigated by the semi-empirical MNDO method. $C_{60}^{1-}$ has the highest stability. The ionization potential values of the $C_{60}$ ions range from 15.31 eV of $C_{60}^{2+}$ to -13.01 eV of $C_{60}^{6-}$. These values show a linear relationship according to charges. The average IP per charge is 3.15 eV from our calculations and 3.22 eV from the linear function of IP. A charge- or electron-transfer reaction of $C_{60}^{n+}$ will only occur if the ionization potential of any guest molecule is lower than the electron affinity of the host $C_{60}^{n+}$. If the energy gap between ionization potential and electron affinity, ${\Delta}_{IP-EA}$, is high, charge-transfer reactions arise by the charge-controlled effect. However, if ${\Delta}_{IP-EA}$ is low, electron-transfer reactions arise by the frontier-controlled effect.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.11 no.4
• /
• pp.354-358
• /
• 2001

This paper presents a fuzzy neural network model which solves the underutilization problem. This fuzzy neural network has both stability and flexibility because it uses the control structure similar to AHT(Adaptive Resonance Theory)-l neural network. And this fuzzy nenral network does not need to initialize weights and is less sensitive to noise than ART-l neural network is. The learning rule of this fuzzy neural network is the modified and fuzzified version of Kohonen learning rule and is based on the fuzzification of leaky competitive leaming and the fuzzification of conditional probability. The similarity measure of vigilance test, which is performed after selecting a winner among output neurons, is the relative distance. This relative distance considers Euclidean distance and the relative location between a datum and the prototypes of clusters. To compare the performance of the proposed fuzzy neural network with that of Kohonen Self-Organizing Feature Map the IRIS data and Gaussian-distributed data are used.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.2
• /
• pp.337-345
• /
• 2002

The equilibrium structures for the ground and transition states of $C_7H_7^+$ isomers have been investigated using sophisticated ab initio quantum mechanical techniques with various basis sets. The structures of tropyrium and benzyl cations have been fully optimized at the DZP CCSD(T) levels of theory. And the structures of o-, m-and p-tolyl cations are optimized fully up to the DZ CCSD(T) levels of theory. The geometries for the transition states between three isomers of tolyl cations have been optimized up to DZP CISD level of theory. The SCF harmonic vibrational frequencies for tropylium, benzyl, and three isomers of tolyl cations are all real numbers, which confirm the potential minima and each unique imaginary vibrational frequencies for TS1 and TS2 confirm the true transition states. The relative energy of the benzyl cation with respect to the tropyrium cation is predicted to be 28.5 kJ/mol and is in good agreement with the previous theoretical predictions. The 0 K heats of formation, ${\Delta}H^{\circ}_{f0}$, have been predicted to be 890, 1095, 1101, and 1110 kJ/mol for tropylium, ortho-, meta-, and para-tolyl cations by taking the experimental value of 919 kJ/mol for the benzyl cation as the base level. The relative stability between tolyl cations is in the order of ortho

• Korean Journal of Applied Biomechanics
• /
• v.17 no.4
• /
• pp.27-36
• /
• 2007

The purpose of this study was to investigate the effect of the upper body in order to increase a propulsive force in the old's walking. The subjects were each 10 males, the latter term of the aged and former term of the aged. There were three walking speeds of slow(about 5km/h), medium(about 6km/h), and maximum speed(about 7km/h). The subjects walking 11m were filmed the 5m section (from 3m to 8m) by 2-video cameras using three dimensional cinematography. And we computed different mechanical quantities and especially computed the relative momentum in order to achieve this study's aim. In this study, we was able to acquire some knowledge. The step length and step frequency increased in proportion to the walking speed, and the faster walking speed, the shorter ratio of supporting time( both legs supporting time/one step length time). When it was one leg support phase, the torso was indicated to generate the momentum in order to produce the propulsive force of walking. The upper and lower body had a cooperative relation for walking such as keeping step rate with the arms to legs and maintaining the body balance. The opposition phase for upward-and-downward direction of the torso and arms in walking was functioned to prevent the increase rapidly toward vertical direction of the center of gravity. The arms had contributed to coordinate the tempo of legs and the posture maintenance of the upper body. And by absorbing the relative momentum from the upper torso with arms to the lower torso, it had the rhythmical movement on upward-and-downward direction reducing the vertical reaction force. On account of the relations of absorption and generation of the propulsive force and the production of vertical impulse in the lower torso when walking by maximum speed, it was showed that the function of lower torso was come up as important problem for the mechanical posture stability and propulsive force coordination.

• Journal of the Korean Ceramic Society
• /
• v.30 no.8
• /
• pp.657-663
• /
• 1993

BaTiO3 sputtering targets of 3 inch diameter were prepared by sintering the CIP (Cold Isotatic Pressing) compacts at 136$0^{\circ}C$ for 3hrs. The apparent density and grain size were 97% and 30${\mu}{\textrm}{m}$, respectively. After BaTiO3 films were deposited on Si and Pt/Ti/SiO2/Si substrates using these targets, films were annealed at various conditions and the crystallization behavior, reaction with the substrate and the electrical properties were investigated. The films on both substrates required 5~20hrs furnace annealing for crystallization at the temperatures from $600^{\circ}C$ to 80$0^{\circ}C$. For the films on Si substrate, interaction between the film and the substrate was suppressed upt o $700^{\circ}C$ for 10 hrs and the relative dielectric constant was 30. As the annelaing temperature and time were increased, the relative dielectric constants of the films decreased due to the formation of silicate phases through the reaction with the substrate. For the BaTiO3 films on Pt/Ti/SiO2/Si substrate, the reaction with the substrate was further reduced when the annealing condition was identical to that for Si substrate, but the reaction between the layers in Pt electrode took place above $700^{\circ}C$. When the films were annealed at $600^{\circ}C$ where the stability of Pt electrode was sustained, relative dielectric constant was increased to 110 since the reaction with substrate was effectively reduced even for a longer annealing time and the crystallization was enhanced.

• BMB Reports
• /
• v.28 no.6
• /
• pp.515-522
• /
• 1995

The effects of the thyroid hormone ($T_3$) on 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity were evaluated in a baby hamster kidney cell line, C100. The cells cultured in MEM were supplemented with 10% thyroid hormone-depleted fetal bovine serum (THDS-MEM) and had a 82.5% lower level of HMG-CoA reductase activity than the cells grown in a medium supplemented with fetal bovine serum (FBS-MEM). When $T_3$ was supplemented to THDS-MEM, the reduction of the reductase activity was blocked in a dose-dependent manner. In the cells grown in THDS-MEM containing $T_3$ at a concentration of $10^{-6}$ M, the level of HMG-CoA reductase activity was 91.8% relative to the cells grown in FBS-MEM. These changes in HMG-CoA reductase activity seemed to be at least partly due to the changes of HMG-CoA reductase mRNA levels. The level of HMG-CoA reductase mRNA in cells incubated in THDS-MEM decreased to 76.2% relative to the cells grown in FBS-MEM, while the level of reductase mRNA in cells incubated in THDS-MEM containing $T_3$ at a concentration of $10^{-6}$ M increased to 243.4% relative to the cells grown in FBS-MEM. The increase of HMG-CoA reductase mRNA level after $T_3$ treatment may have been due to the increased stability of reductase mRNA, because the transcriptional rate of the reductase gene did not change significantly in the presence or absence of $T_3$. These results indicate that $T_3$ stabilizes HMG-CoA reductase mRNA at the posttranscriptional level and regulates HMG-CoA reductase activity in a dose-dependent manner.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.6
• /
• pp.890-897
• /
• 2021

Since the enforcement of strict regulations on marine fuel oil sulfur content, demand for Low Sulfur Fuel Oil (LSFO) has been increasing. However, as LSFO properties vary greatly depending on the supply timing, region, and supplier, LSFOs can experience problems with sludge formation, blending compatibility, and stability once mixed into storage tanks. This study investigates using ultrasound cavitation effects to improve the quality of LSFOs in storage tanks. For marine gas oil (MGO), the results showed that the relative ratio of high molecular weight compounds to those of low molecular weight decreased after ultrasonic irradiation, due to cavitation-induced cracking of chemical bonds. For marine diesel oil (MDO) and blended oil, a small increase in the relative abundance of low weight molecular compounds was observed after treatment. However, no correlation between time and relative abundance was observed.

• Journal of Korean Society of Water and Wastewater
• /
• v.35 no.1
• /
• pp.53-61
• /
• 2021

The quantified analysis of damages to wastewater treatment plants by natural disasters is essential to maintain the stability of wastewater treatment systems. However, studies on the quantified analysis of natural disaster effects on wastewater treatment systems are very rare. In this study, a total disaster index (DI) was developed to quantify the various damages to wastewater treatment systems from natural disasters using two statistical methods (i.e., AHP: analytic hierarchy process and PCA: principal component analysis). Typhoons, heavy rain, and earthquakes are considered as three major natural disasters for the development of the DI. A total of 15 input variables from public open-source data (e.g., statistical yearbook of wastewater treatment system, meteorological data and financial status in local governments) were used for the development of a DI for 199 wastewater treatment plants in Korea. The total DI was calculated from the weighted sum of the disaster indices of the three natural disasters (i.e., TI for typhoon, RI for heavy rain, and EI for earthquake). The three disaster indices of each natural disaster were determined from four components, such as possibility of occurrence and expected damages. The relative weights of the four components to calculate the disaster indices (TI, RI and EI) for each of the three natural disasters were also determined from AHP. PCA was used to determine the relative weights of the input variables to calculate the four components. The relative weights of TI, RI and EI to calculate total DI were determined as 0.547, 0.306, and 0.147 respectively.

• Proceedings of the National Institute of Ecology of the Republic of Korea
• /
• v.5 no.1
• /
• pp.10-20
• /
• 2024

The study investigated species diversity, relative abundance, and decline of flying insects and plants within a fragmented forest in the Federal University of Technology Akure (FUTA), Ondo State, Nigeria. It is known that habitat fragmentation can reduce biodiversity. Thus, it is important to perform comprehensive assessments to understand implications of the habitat fragmentation for flora and fauna. Species richness and abundance of flying insects and plants across fragmented forest patches were quantified using field surveys and taxonomic identification. This study revealed shifts in species diversity, with fragmented areas exhibiting reduced biodiversity compared to contiguous forest ecosystems. Flying insects crucial for ecosystem functioning and pollination services demonstrated decreased species richness and relative abundance within fragmented habitats. This decline was attributed to habitat loss, altered microclimates, and limited movement pathways known to hinder insect dispersal. Similarly, plant species richness and abundance showed decline in fragmented forest due to disrupted mutualistic interactions with pollinators, altered nutrient cycling, and increased competition among plant species. This study underscores the importance of maintaining intact forest habitats to sustain healthy ecosystems and preserve biodiversity. Effective conservation strategies should focus on habitat connectivity, reforestation efforts, and protection of essential ecological corridors to mitigate effects of fragmentation. In conclusion, this investigation provides empirical evidence for effects of habitat fragmentation on flying insects and plants in a forest ecosystem in FUTA Akure, Nigeria. Findings emphasize an urgency of adopting conservation measures to safeguard these invaluable components of biodiversity and ecosystem stability in the face of ongoing habitat loss and fragmentation.