• Journal of Microbiology and Biotechnology
• /
• v.20 no.1
• /
• pp.110-116
• /
• 2010

Lactic acid (LA) fermentation by Lactobacillus salivarius ATCC 11741 immobilized on loofa sponge (LS) was evaluated. To increase the surface area of LS for cell immobilization, $H_2O_2$ and chitosan were introduced as surface modifying reagents. Four chitosans of different molecular weights were separately coated on LS. All experiments were conducted in shaking flask mode at 100 rpm rotating speed and $37^{\circ}C$ with 5% $CaCO_3$ as a pH regulating agent. The effects of initial glucose concentration were investigated in the range of 20-100 g/l on LA fermentation by free cells. The results indicate that the maximum concentration of LA was produced with 50 g/l glucose concentration. The immobilized cell system produced 1.5 times higher concentration than free cells for 24 h of fermentation. Moreover, immobilized cells can shorten the fermentation time by 2-fold compared with free cells at the same level of LA concentration. At 1% (w/v) chitosan in 2% (v/v) acetic acid, the Yp/s and productivities of various molecular weights of chitosans were insignificantly different. Repeated batch fermentations showed 5 effective recycles with Yp/s and productivity in the range of 0.55-0.85 and 0.90-1.20 g/l.h, respectively. It is evident that immobilization of L. salivarius onto LS permits reuse of the system under these fermentation conditions. Scanning electron micrographs indicated that there were more intact cells on the chitosan-treated LS than on the untreated LS, thus confirming the effectiveness of the LS-chitosan combination when being utilized as a promising immobilization carrier for LA fermentation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.12
• /
• pp.6208-6214
• /
• 2012

The most essential but missing components to understand and use toxic substances from marine microalgae are developing the fast, easy and economical determining technology for detecting it. In this paper we produced the antibodies against saxitoxin (STX). Mariculture keyhole limpet hemocyanin (mcKLH) and ovalbumin (OVA) were used as carrier proteins. mcKLH-STX conjugates were injected into the peritonial cavity of BALB/c mouse for immunization. After bleeding from mouse, anti-STX antiserum was isolated. Indirect enzyme-linked immunosorbent assays (ELISA) was performed to determine antiserum titer using the microtiter plate coated with free STX and OVA-STX. A goat anti-mouse IgG-phosphatase conjugate was used as secondary antibody to enable chromogenic reaction. Reactions of anti-STX antiserum were very specific on the OVA-STX and free STX. Sensitivity of anti-STX antiserum on STX was very high and STX detection limit was to be 64.9 ng/kg for indirect ELISA.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.6
• /
• pp.2770-2776
• /
• 2011

Mutual Interference scenarios between Wireless Broadband (WiBro) and Wireless LAN (WLAN) in DTV bands are assumed. Co-channel interference and adjacent channel interference are respectively evaluated in terms of carrier to interference ratio (C/I) by using Spectrum Engineering Advanced Monte Carlo Analysis Tool (SEAMCAT) based on the Monte-Carlo simulation method. For the simulation, three frequencies such as 185 MHz, 481 MHz and 687 MHz are chosen. Analysis results indicate that interference situation of using frequency of 185 MHz is the worst case, which requires longer protection distance between WiBro MS and WLAN User Equipment (UE), lower transmit power of WiBro Mobile Station (MS) and WiBro Base Station (BS) and WLAN UE and larger guard band. Comparing to cases of using frequency of 185 MHz and 481 MHz, interference situation of using frequency of 687 MHz is slighter. Therefore, using frequency of 687 MHz is easier for coexistence between WiBro and WLAN. Analysis results can be used as reference and guideline when planning the deployment of WiBro and WLAN in DTV bands.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.3
• /
• pp.366-374
• /
• 2015

Herein, we established a repeated-batch process for ethanol production from glycerol by immobilized Pachysolen tannophilus. The aim of this study was to develop a more practical and applicable ethanol production process for biofuel. In particular, using industrial-grade medium ingredients, the microaeration rate was optimized for maximization of the ethanol production, and the relevant metabolic parameters were then analyzed. The microaeration rate of 0.11 vvm, which is far lower than those occurring in a shaking flask culture, was found to be the optimal value for ethanol production from glycerol. In addition, it was found that, among those tested, Celite was a more appropriate carrier for the immobilization of P. tannophilus to induce production of ethanol from glycerol. Finally, through a repeated-batch culture, the ethanol yield (Y_e/g) of 0.126 ± 0.017 g-ethanol/g-glycerol (n = 4) was obtained, and this value was remarkably comparable with a previous report. In the future, it is expected that the results of this study will be applied for the development of a more practical and profitable long-term ethanol production process, thanks to the industrial-grade medium preparation, simple immobilization method, and easy repeated-batch operation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.10
• /
• pp.1109-1115
• /
• 2010

FMCW(Frequency Modulation Continuous Wave) Radar can detect the distance and the velocity of forward obstacles using linearly modulated FM signal. For better performance, the RF of radar should be operated with wideband frequency linearity on 300 MHz bandwidth at 77 GHz carrier frequency. In this paper, we propose a simple method for improving frequency linearity of FMCW radar implemented with VCO. The proposed method shows that the Voltage-Frequency relation of VCO could be measured by using the modified Tx waveform of FMCW radar. Then the measured nonlinearity could be compensated using LUT(Look-up Table) with easy. It is noted that the proposed can be adopted in existing system without extra circuit.

• Journal of Korea Society of Industrial Information Systems
• /
• v.17 no.2
• /
• pp.19-27
• /
• 2012

In railway tunnel environment, the reliability of a high-data-rate and real-time train-to-wayside communication should be maintained especially when high-speed train moves along the track. In China and Europe, the communication frequency around 900 MHz is widely used for railway applications. At this carrier frequency band, both of the solutions based on continuously laid leaky coaxial cable (LCX) and discretely installed base-station antennas (BSAs), are applied in tunnel radio coverage. Many available works have concentrated on the radio-wave propagation in tunnels by different kinds of prediction models. Most of them solve this problem as natural propagation in a relatively large hollow waveguide, by neglecting the transmitting/receiving (Tx/Rx) components. However, within such confined areas like railway tunnels especially loaded with train, the complex communication environment becomes an important factor that would affect the quality of the signal transmission. This paper will apply a full-wave numerical method to this case, for considering the BSA or LCX, train antennas and their interacted environments, such as the locomotive body, overhead line for power supply, locomotive pantograph, steel rails, ballastless track, tunnel walls, etc.. Involving finite-difference time-domain (FDTD) method and uni-axial anisotropic perfectly matched layer (UPML) technique, the entire wireless RF downlinks of BSA and LCX to tunnel space to train antenna are precisely modeled (so-called integrative modeling technique, IMT). When exciting the BSA and LCX separately, the field distributions of some cross-sections in a rectangular tunnel are presented. It can be found that the influence of the locomotive body and other tunnel environments is very significant. The field coverage on the locomotive roof plane where the train antennas mounted, seems more homogenous when the side-laying position of the BSA or LCX is much higher. Also, much smoother field coverage solution is achieved by choosing LCX for its characteristic of more homogenous electromagnetic wave radiation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.10
• /
• pp.4296-4301
• /
• 2011

Gantry loader which is also called as gantry robot is a kind of cartesian coordinate robot with two or more linear motions. A conventional gantry system has cableveyor for protecting power and signal cables, but the use of cableveyor makes a delay of work due to frequent repairing for its aging. This study reports that a wireless gantry loader is able to be operated without a power line for power transmission or a signal cable for motion control. The wireless gantry loader enables a convenient maintenance and a stable productivity by the reduction of wire broken from fatigue. The developed loader system is controlled by PC-based motion controller and is communicated by wireless LAN devices. The line from a power source to the loader system was substituted by attaching trolley bar on the traveling beam. The loader system was designed to be moved with high speed and high repeatability, and the motion was observed continuously by monitoring system in the PC-based controller. The maximum speed and the repeatability for the transferring and loading axes are 200 m/min, 60 mm and 100 m/min, 40 mm respectively.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.6
• /
• pp.2743-2748
• /
• 2013

The vitamin gets through food and the sun. But there is case that density alters by certain factor in vitamin. So this research analyzed effect of the liver function factor and change of $25OH-VIT.D_3$ density. Research target is a person who undergo health medical examination in the certain university hospital medical examination center from August, 2012 to December, 2012. Comparison classified to experiment group and control group. As a result, variable that influence in $25OH-VIT.D_3$ density showed by age and B type inflammation of the liver titer. Specially, B type inflammation of the liver titer displayed reverse corelation ($R^2$=0.40). Therefore, inflammation of the liver carrier must manage liver fuction test and density of $25OH-VIT.D_3$.

• Journal of Korea Society of Industrial Information Systems
• /
• v.19 no.6
• /
• pp.131-150
• /
• 2014

This study investigates factors, which affect subjective judgment of Smartphone users when they switch to a new product or other mobile carrier, and examine a relationship between switching intention and switching expected performance through users of in Korea and China. The results of the study showed that switching intention is positively associated with switching expected performance in both Korean and Chinese users. Brand reliability, functional quality, and general climate for Smartphone business have a significant impact on switching intention in both countries. In addition, personal innovation has a significant impact on switching intention of Korean users but Chinese. However, content quality has the effect on switching intention of Chinese user but Korean. This study provides useful strategies for switching behavior of Smartphone users of two different countries in the mobile industry.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.40 no.3
• /
• pp.123-137
• /
• 2017

Competitiveness of small and medium companies often rely on the competency of their employees. Many employees however try to move to better environments if possible, which results in high uncertainty in maintaining solid human resources. The purpose of this paper is to investigate the influencing factors of turnover intention and organizational loyalty of the early experienced, especially three to five years experienced, employees in the small and medium enterprises. A survey had been conducted using both LMX (Leader Member eXchange) and TMX (Team Member eXchange) as an effort to test the impact of strategic human resource management factors on turnover intension and organizational loyalty. It has been observed that the level of LMX is critical on the turnover intension, while the levels of LMX and TMX are positively related to the organizational loyalty. Especially significant mediation effect affects on the organizational loyalty for TMX via LMX in the serial structure. The human resource management factors become effective under the circumstances where leader and team members exchange activities are activated. These findings can be used in reducing turnover intention and increasing organizational loyalty of early experienced employees by enhancing the leadership training of middle level managers of the small and medium enterprises organizations. Besides, a set of active communication channels should be provided for the young employees so that they can share their work experiences and difficulties within the organization. The key results of this study may help the practitioners set up a management plan to maintain a low turnover rate for their organizations.