• Korean Journal of Materials Research
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• v.29 no.1
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• pp.59-64
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• 2019

This study investigates the optical characteristics of InGaN multiple quantum wells(MQWs) light emitting diodes(LEDs) on planar sapphire substrates(PSSs), nano-sized PSS(NPSS) and micro-sized PSS(MPSS). We obtain the results as the patterning size of the sapphire substrates approach the nanometer scale: The light from the back side of the device increases and the total light extraction becomes larger than the MPSS- and planar-LEDs. The experiment is conducted by Monte Carlo ray-tracing, which is regarded as one of the most suitable ways to simulate light propagation in LEDs. The results show fine consistency between simulation and measurement of the samples with different sized patterned substrates. Notably, light from the back side becomes larger in the NPSS LEDs. We strongly propose that the increase in the light intensity of NPSS LEDs is due to an abnormal optical distribution, which indicates an increase of extraction probability through NPSS.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.391-395
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• 2012

We present a continuous cell separator that achieves density-dependent and size-independent cell separation based on the net force of gravity and buoyancy forces on the cells in dissimilar density fluids. Previous cell separators are, based on the size or dielectrophoretic property of the cells and, are suitable for size-dependent and density-independent cell separation. However, these properties can make it difficult to collect the same types of cells with the same density but with size variations. The present separator, however, is capable of collecting the same types of cells based on the cell density in the fluid. Regardless of cell size, the proposed chip isolates low density cells, (white blood cells, or WBCs) at the upper outlet while obtaining high-density cells (red blood cells, or RBCs) from the lower outlet based on density. Efficiency levels for separation of WBCs and RBCs were $90.9{\pm}9.1%$ and $86.4{\pm}1.99%$, respectively. The present separator therefore has the potential for use in the pretreatment of whole blood.

• KSBB Journal
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• v.22 no.6
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• pp.371-377
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• 2007

Polyhydroxyalkanoates (PHAs) are a family of microbial polyesters that can be produced by fermentation from renewable resources. PHAs can be used as completely biodegradable plastics or elastomers. In this paper, novel applications of PHAs in biosensor are described. A general platform technology was developed by using the substrate binding domain (SBD) of PHA depolymerase as a fusion partner to immobilize proteins of interest on PHA surface. It could be shown that the proteins fused to the SBD of PHA depolymerase could be specifically immobilized onto PHA film, PHA microbead, and microcontact printed PHA surface. We review the results obtained for monitoring the specific interaction between the SBO and PHA by using enhanced green fluorescent protein, red fluorescent protein, single chain antibody against hepatitis B virus preS2 surface protein and severe acute respiratory syndrome coronavirus surface antigen as model proteins. Thus, this system can be efficiently used for studying protein-protein and possibly protein-biomolecule interactions for various biotechnological applications.

• Journal of Bio-Environment Control
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• v.23 no.2
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• pp.158-166
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• 2014

This experiment has investigated suitable methods to improve precision water content monitoring of coconut coir substrates to control irrigation by frequency domain reflectometry(FDR) sensors. Specifically, water content changes and variations were observed at different sensing distances and positions from the irrigation dripper location, and different spaces between the FDR sensors with or without noise filters. Commercial coconut coir substrates containing different ratios of dust and chips(10:0, 7:3, 5:5, 3:7) were used. On the upper side and the side of the substrates, a FDR sensor was used at 5, 10, 20, 30cm distances respectively from the irrigation dripper point, and water content was measured by time after the irrigation. In the glass beads, sensors were installed with or without noise filtering. Closer sensing distance had a higher water content increasing rate, regardless of different coir substrate ratios. There were no differencies of water content increasing rates in 10:0 and 3:7 substrates between the upper side and the side. Whereas, 7:3 and 5:5 substrates showed higher increasing rates on the upper side measurements. Substrates with higher ratios of chip(3:7) had lower increasing rates than others. And, with noise filters, the exatitude of measurement was improved because the variation and deviation were reduced. Therefore, in coconut coir with FDR sensors, an efficient water content measurment to control irrigations can be achieved by installing sensors closer to an irrigation point and upper side of substrates with noise filters.

• Korean Journal of Agricultural Science
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• v.30 no.1
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• pp.76-88
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• 2003

This study exploits the robot system which is necessary in gene study, bio-technology industry. As well, it can achieve the job of DNA chip manufacturing whose use rate has been increased recently. The robot consists of DNA spotting device for spotting DNA on the silylated slide and well plate, bed for fixing well-plate, washing & drying device of washing and drying the pin part of DNA spotting device, distillation-water vessel, and discharge vessel of wash water. We made the term of sticking DNA to the pin on well plate to be 15 seconds. The spot size of DNA was set to be 0.28 mm on the average by bringing the slide into contact with pin for 1 second. At this rate, if DNA is spotted in the minimum space possible of about 0.32mm, it can stick about 8,100 DNA spots on the well plate. Analyzing the procedure: Movement starts. Pin washes, dries, and smears DNA on the well plate. Spots DNA onto 12 chips takes 2 minutes and 50 seconds.

• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.87-100
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• 2003

It is important to understand the potential human health implications of exposure to environmental chemicals that may act as hormonally active agents. It is necessary to have an understanding of how pharmaceutical and personal care products and other chemicals affect the ecosystem of our planet as well as human health. Endocrine disruption is defined as the ability of a chemical contaminating the workplace or the environment to interfere with homeostasis, development, reproduction, and/or behavior in a living organism or it's offspring. Certain classes of environmentally persistent chemicals such as polychlorinated biphenyls (PCBs), dioxins, furans, and some pesticides can adversely effect the endocrine systems of aquatic life and terrestrial wildlife. Research continues to support the theory of endocrine disruption. However, endocrine disruption researches have been applied to proteomics poorly. Proteomics can be defined as the systematic analysis of proteins for their identity, quantity and function. It could increase the predictability of early drug development and identify non-invasive biomarkers of tonicity or efficacy. Proteome analysis is most commonly accomplished by the combination of two-dimensional gel electrophoresis (2D/E) and MALDI-TOF mass spectrometry (MS) sr protein chip array and SELDI-TOF MS. Proteomics have an opportunity to play an important role in resolving the question of what role endocrine disruptors play in initiating human disease. Proteomics can also play an imfortant role in the evaluation of the risk assessment and use of risk management and risk communication tools required to address public health concerns related to notions of endocrine disruptors. Understanding the need for the proteomics and possessing knowledge of the developing biomakers used to abbess endocrine activity potential will he essential components relevant to the topic of endocrine disruptors.

• Journal of Life Science
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• v.26 no.7
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• pp.789-795
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• 2016

A lymph node (LN) is one of the secondary lymphoid organs. An LN consists of a complicated 3 dimensional frame structure and several stromal cells. Fibroblastic reticular cells (FRC) are distributed in the T zone for interaction with T cells. FRC secrete homing chemokines such as CCL19 and CCL21. Moreover, FRC play a pivotal role in the production of extracellular matrix (ECM) into LN for ECM reorganization against pathogen infections. However, not much is known about the involvement of the immune reaction of FRC. The present report is for the characterization of FRC on immune response. For this, FRC were positioned in several infected situations such as co-culture with macrophage, lipopolysaccharide (LPS), and TNFα stimulation. When a co-culture between FRC and macrophage was performed, a morphological change in FRC was observed, and empty space between FRCs was created by this change. The soluble ICAM-1 protein level was up-regulated by co-culturing with Raw264.7 and the treatment of the ROCK inhibitor Y27632. The activity of matrix metalloproteinase (MMP) was up-regulated by LPS onto FRC. Furthermore, the inflammatory cytokine TNFα regulated the expression of ECM in FRC by a gene chip assay. Collectively, it suggests that FRC are involved in immune reactions.

• Journal of the Korea Society of Computer and Information
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• v.17 no.4
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• pp.1-9
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• 2012

As we are turnning into the aged society, accidents by falling down are increasing in the aged people's group. In this paper, we design the system with the 3-Axis acceleration sensor which is composed by a single chip. The body activity signal is measured with the signal detector and RF communicator in this proposed system and the and falling by the entering signal pattern analysis with 3-Axis acceleration sensor. For the RF communication, we are using nRF24L01p and 8bits ATmega uC for the processor. The error of energy expenditure estimation between motor driven treadmill and proposed a body activity module was 7.8% respectively. Human activities and falling is monitored according to analyze and judge the critical value of the Signal Vector. as falled down if they don't turn off the alarm after specific period and the aged person's after falling down activities are their position and more.

• Journal of Life Science
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• v.26 no.9
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• pp.1027-1032
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• 2016

Antigen is substance causing disease derived from pathogen. Living organism has the immune system in terms of defense mechanism against antigen. Antigen is processed through several pathways such as phagocytosis, antibody action, complement activation, and cytotoxins by NK or cytotoxic T lymphocyte via MHC molecule. Lymph node (LN) is comprised of the complicated 3 dimensional network and several stromal cells. Fibroblastic reticular cells (FRC) are distributed in T zone for interaction with T cells. FRC produces the extra cellular matrix (ECM) into LN for ECM reorganization against pathogen infections and secretes homing chemokines. However, it has not so much been known about the involvement of the antigen process of FRC. The present report is for the function of FRC on antigen process. For this, FRC was positioned with several infected situations such as co-culture with macrophage, T cell, lipopolysaccharide (LPS) and TNFα stimulation. When co-culture between FRC with macrophage and T cells was performed, morphological change of FRC was observed and empty space between FRCs was made by morphological change. The matrix metallo-proteinase (MMP) activity was up-regulated by Y27632 and T cells onto FRC. Furthermore, inflammatory cytokine, TNFα regulated the expression of adhesion molecules and MHC I antigen transporter in FRC by gene chip assay. NO production was elevated by FRC monolayer co-cultured with macrophage stimulated by LPS. GFP antigen was up-taken by macrophage co-cultured with FRC. Collectively, it suggests that FRC assists of the facilitation of antigen process and LN stroma is implicated into antigen process pathway.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1721-1725
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• 2010

This paper reports the fabrication of geometry-controlled carbon microneedles by a backside exposure method and pyrolysis. The SU-8 microneedles are a polymer precursor in a carbonization process, which geometries such as base diameter, spacing, and aspect ratio can be controlled in a photolithography step. Using this fabrication method, highly reproducible carbon microneedles, which have high aspect ratios of more than 10 and very sharp nanotips, can be realized. The quartz surface with carbon microneedles becomes very hydrophilic and its wettability is adjusted by carrying out the silane treatment. In the carbon microneedle array ($3\;{\mu}m{\times}3\;{\mu}m$), the contact angle is extremly enhanced (${\sim}180^{\circ}$); this will be advantageous in developing low-drag microfluidics and labs-on-a-chip as well as in other bio-applications.