• Journal of Korean Society of Transportation
• /
• v.23 no.2
• /
• pp.151-160
• /
• 2005

In case of public transit such as bus system, the probability concept is used to evaluate the Level-of-Service of the operations. And each levels could be classified according to the linear probability value. (TCQSM: Transit Capacity and Quality of Service Manual-2nd Edition, TRB, Washington DC., 2003) In this case, the drivers or passengers wouldn't think that the service level isn't equivalent to the linear probability value. Thus the linear probability value doesn't exactly reflect the service level. This study shows the problems of using the linear probability value in classifying the service level through the case of evaluation of bus operation's punctuality, presented in TCQSM. To make up for the problems of such case, two methodologies are presented in this study. The method of determining Level-of-Service criteria using probability density of headway variation's distribution, presented in this paper, adequately reflects passenger's expected waiting time. According to the application result to real bus operation data, it tis better than the method of TCQSM to evaluate the reliability of bus operations. However further research about the relations between utility difference and passenger feeling of service level in necessary to apply the method that uses the utility function. It remains as the limitation of this paper.

• Molecules and Cells
• /
• v.44 no.9
• /
• pp.647-657
• /
• 2021

As a pancreatic inflammatory marker, regenerating islet-derived protein 3A (Reg3A) plays a key role in inflammation-associated pancreatic carcinogenesis by promoting cell proliferation, inhibiting apoptosis, and regulating cancer cell migration and invasion. This study aimed to reveal a novel immuno-regulatory mechanism by which Reg3A modulates tumour-promoting responses during pancreatic cancer (PC) progression. In an in vitro Transwell system that allowed the direct co-culture of human peripheral blood-derived dendritic cells (DCs) and Reg3A-overexpressing/ silenced human PC cells, PC cell-derived Reg3A was found to downregulate CD80, CD83 and CD86 expression on educated DCs, increase DC endocytic function, inhibit DC-induced T lymphocyte proliferation, reduce IL-12p70 production, and enhance IL-23 production by DCs. The positive effect of tumour-derived Reg3A-educated human DCs on PC progression was demonstrated in vivo by intraperitoneally transferring them into PC-implanted severe combined immunodeficiency (SCID) mice reconstituted with human T cells. A Reg3A-JAK2/STAT3 positive feedback loop was identified in DCs educated with Reg3A. In conclusion, as a tumour-derived factor, Reg3A acted to block the differentiation and maturation of the most important antigen-presenting cells, DCs, causing them to limit their potential anti-tumour responses, thus facilitating PC escape and progression.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.27 no.2
• /
• pp.277-284
• /
• 2024

For the high reliability of guidance weapon, it is important to maintain the stable supply voltage for guidance system while the bomb is gliding. However, the DC motor drive for guidance control in the low temperature can lead to the critical voltage drop due to a large inrush current. In this paper, we propose the wing deployment logic design to enhance the guidance system stability. To derive the stable drive logic based on PWM, we controlled the duty cycles for input voltage of DC motor in low temperature. The initial duty cycle was set to 40 % to relieve the inrush current. Moreover, the proper time, which is less than 1 second for controlling duty cycles, was determined by the iterative wing deployments of guidance kit. Finally, the validity of proposed logic was confirmed from the result the maximum voltage drop for the wing deployment was decreased by 23 %.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.7 s.110
• /
• pp.605-614
• /
• 2006

In this paper, a 3D structure skimmer-shaped circular microstrip antenna is designed, the ends of whose both sides are made as DC(Depressed Carving part) applying perturbation effect to reduce the patch size of microstrip antenna operating at design frequency 1.575 GHz. The result shows its return loss, - 10 dB bandwidth, gain, - 3 dB beamwidth E, H-plane are -26.59 dB, 65 MHz(4.13 %), 4.66 dBd, $79^{\circ},\;87^{\circ}$ respectively. The diameter of the antenna is 85 mm, which is 12.4 % reduced compared to the size(97 mm) of general microstrip patch antenna. Therefore its area reduction is 23.2 %. Furthermore, a linear and circular polarized baseball-shaped circular microstrip antenna is designed to minimize the patch size of the antenna. This structure of antenna operating at the design frequency 1.575 GHz is applied with the optimum RC(Raised Carving part) & DC ratio and an asymptotic line angle. In case of linear polarized baseball-shaped circular microstrip antenna, the patch size of the antenna is 74 mm, which is 41.8 % area reduction compared to general microstrip patch antenna. In case of circular polarized baseball-shaped circular microstrip antenna, the diameter of patch is 82 mm, which is 28.5 % area reduction compare to general microstrip patch antenna linear polarized. We have verified that the perturbation effect can be applied to minimize the circular microstrip antenna.

• Journal of Technology Innovation
• /
• v.23 no.3
• /
• pp.137-167
• /
• 2015

Based on the stakeholder theory, this paper analyzes a clash of standards in Korea's Electric Vehicle(EV) market, particularly between an EV charging standard and a smart grid communication standard in 2012~2013. For charging, EV is connected with the electric power grid and simultaneously exchanges data regarding the charging status. When EV is connected with the power grid, a clash between two standards may arise. It actually happened when BMW entered into the Korean EV market with the DC Combo charging system. In that course, the frequency interference occurred between the EV data communication technology adopted by BMW and the AMI(Advanced Metering Infrastructure) for the smart grid system in Korea. Standardization of Korea's EV charging systems was required to solve this problem. However, it had been delayed due to the confrontation between various stakeholders involved in the process of standardization. It lasted until the DC combo was accepted as one of the Korea EV charging standards(KSAE SAE 1772-2040, 2014.1) by KSAE(The Korea Society of Automotive Engineers) in January 2014. This is an interesting case in the age of convergence. As it deals with the standard competition not among EV standards, but a clash between the EV industry and the smart grid, i.e. electric power industry, it addresses the necessity to consider standardization processes between different industries. This study draws on the stakeholder theory to analyse the dynamics of the standard clash between EV charging systems and the smart grid system, which is a unique example of standard clash between different industries. We expect such clashes to increase in the age of convergence.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.41 no.11
• /
• pp.21-27
• /
• 2004

In this paper, millimeter-wave monolithic integrated circuit(MIMIC) low noise amplifier(LNA) for V-band, which is applicable to 60 GHz wireless local area network(WLAN), was fabricated using the high performance 0.1 ${\mu}{\textrm}{m}$ $\Gamma$-gate pseudomorphic high electron mobility transistor(PHEMT). The DC characteristics of PHEMT are drain saturation current density(Idss) of 450 mA/mm and maximum transconductance(gm, max) of 363.6 mS/mm. The RF characteristics were obtained the current gain cut-off frequency(fT) of 113 GHz and the maximum oscillation frequency(fmax) of 180 GHz. V-band MIMIC LNA was designed using active and passive device library, which is composed of 0.1 ${\mu}{\textrm}{m}$ $\Gamma$-gate PHEMT and coplanar waveguide(CPW) technology. The designed V-band MIMIC LNA was fabricated using integrated unit processes of active and passive device. The measured results of V-band MIMIC LNA are shown S21 gain of 21.3 dB, S11 of -10.6 dB at 60 GHz and S22 of -29.7 dB at 62.5 GHz. The measured result of V-band MIMIC LNA was shown noise figure (NF) of 4.23 dB at 60 GHz.

• Korean Journal of Food Science and Technology
• /
• v.44 no.3
• /
• pp.373-377
• /
• 2012

This study was carried out in order to investigate the functional properties of 50% methanol extracts from four parts (root, stem, leaf and fruit) of Acanthopanax sessiliflorus by means of measuring the contents of eleutheroside B, E, and total polyphenols as well as determining electron donating ability (EDA), nitrite scavenging ability (NSA), and anticancer activity. The highest contents of eleutheroside B and E were found in the fruit (538.99 ${\mu}g/g$) and the stem (556.00 ${\mu}g/g$). The root extract demonstrated the highest polyphenol content (2.97 mg/g). EDA of the stem and root extracts were 90.21% and 85.71%. All of the extracts showed 81.5-93.0% of NSA at pH 1.2. In addition all extracts indicated no cytotoxicity to normal cell line (DC2.4). The root extract had a 23% inhibitory effect against the stomach cancer cell line (SNU-719). These results revealed that 50% methanol extracts from A. sessiliflorus can be used as a potential resource of nutraceuticals.

• Analytical Science and Technology
• /
• v.23 no.2
• /
• pp.216-223
• /
• 2010

In previous research, results on efficiency versus size and type of Ag particles showed similarity of detection efficiency comparing the particles of flake and spherical type with the gray particle on the market and in the case of nAg (rod, $0.9\;{\mu}m$) particle, relatively good results was given in the various evaluation methods for detection efficiency of latent fingerprint. However, oxidation was occurred when nAg particles laying on nature condition for a month and due to water absorption, detection efficiency was decreased. Therefore, with need to prevent oxidation and water absorption, more research is necessary. In this research, surface modification on nAg particles using silicon oil was conducted in various methods for complementing weakness of oxidation and water absorption. Then detection efficiency of nAg particles and surface modified nAg particles was evaluated by the number of feature points on the surface of non-porous materials (glass, plastic etc.) and degree of particle adhesion with ridges and contrast of detected fingerprint. Improvement of preventing oxidation and water absorbtion was given by surface modification using silicon oil (DC200, 0.5%) on the surface of non-porous materials.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.12
• /
• pp.2674-2685
• /
• 1997

In this paper, the design and imprlementation of dual-band power amplifier which is used as a critical part for mobile phone to be simultaneously working at a dual band, 800MHz CDAM and PCS frequency band is described. DC operating point of power FET is limited to Class-B to enable long talk time considering that the tyupical power range of CDMA phones in working is around 10 to Class-B to enable long talk time considering that the typical power range of CDMA phones in working is around 10 to 15dBm, i.e., liner range. The power amplifier which employs two GaAs FETs with good linerity at a low operating point has duplexer cuplexer circuit to separate two frequency bands at input and output stage. Electromagnetic analysis for via holes and coupling between narrow transmission lines is included to design a circuit. Moduld size of 0.96CC($22{\times}14.5{\times}3mm^3$) and maximum module current of 130mA at output power range, 10 to 15dBm are attained. The power amplifer module has achieved ACPR performance with 2 to 3dB marging from IS-95 requirement at output powers, 23.5dBm for PCS and 28dBm for 800MHz CDMA respectively.

• Journal of agriculture & life science
• /
• v.50 no.3
• /
• pp.31-41
• /
• 2016

This study was conducted to develop a handy earth auger for use in sloppy and rugged forest terrains in order to reduce labor cost which comprises a major part of the production costs in forest afforestation projects. The first prototype is developed consist of two parts, the soil-digging screw and the battery power source. The specifications of the first prototype screw are: length of 170mm, a top diameter of 60mm, bottom diameter of 47mm, 23° angle for each helix, and a 50mm awl-head tip. The use of a single line of screw was selected for reduced weight. In addition, a power source of rotary DC Motor(WD-6G2425, WONILL, Korea) with a maximum torque of 30kgf-cm, rotation of 20-30rpm, K6G30C decelerator with a reduction ratio of 30:1 which could be used with no load for 48 was operated. In consideration of its weight, a lithium battery was utilized in line with the goal of developing a lightweight auger. In order to evaluate the performance of the first prototype, test sites were selected as 6 areas. The rotational force was found to be highest in area A(Solid area), followed by areas F(Mounted slope 40° area) and E(Mounted slope 30° area). It was also observed that in general, the rotational force increased along with the increase in soil depth with the maximum rotational force recorded at 10cm.