• The Journal of the Acoustical Society of Korea
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• v.22 no.3
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• pp.217-223
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• 2003

A novel cooling method induced by acoustic streaming generated by ultrasonic vibration at 30㎑ is presented. Ultrasonic vibration is obtained by piezoelectric devices and the maximum vibration amplitude of 50 m is achieved by including a horn, mechanical vibration amplifier in the system and making the complete system resonate. To investigate the enhancement of heat transfer capability of acoustic streaming, the temperature variations of heat source and air in the vicinity of heat source are measured in real-time. It is observed that acoustic streaming is instantly induced by ultrasonic vibration, resulting in the significant temperature drop due to the bulk air flow caused by acoustic streaming. In addition, it is observed that the cooling effect on the heat source is maximized when the gap between the ultrasonic vibrator and heat source coincides with the multiples of half-wavelength of the ultrasonic wave. This fact results from the resonance of the sound wave. The theoretical analysis of the dependence on the gap is also accomplished and verified by experiment. The advantage of the proposed cooling method by acoustic streaming is noise-free due to the ultrasonic vibration and maintenance-free because of the absence of moving parts. Moreover. This cooling method can be utilized to the nano and micro-electro mechanical systems, where the fan-based conventional cooling method can not be employed.

• Fire Science and Engineering
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• v.34 no.1
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• pp.135-141
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• 2020

The first case of Middle East Respiratory Syndrome (MERS) was reported in Korea in 2015, after a Korean man from Bahrain tested positive for the infection. After first eruption, there were numbers of secondary infectees and whole country were frightened. At the time, isolated ambulances were available but few, and there was no specific way to prevent contamination during transfer. Therefore, Seoul National University Hospital and the University of Seoul developed isolation units and air filters. Four years after the MERS outbreak, this study measured the differential pressure inside and outside the small isolation units based on the differential pressure and air flow derived from simulation and testing, and proposed minimum values for virus leakage and internal sealing. A performance evaluation and testing method for the transfer equipment is proposed. The critical function of the small isolated transport equipment was defined and selected as an evaluation item; performance evaluation was carried out by simulating a real-world case. The results provide the proper pressure configuration of positive and negative pressure inside the segregation feeder; the clear criteria for the HEPA filter; and the performance criteria for the segregation feeder and air purifier.

• Journal of Embryo Transfer
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• v.25 no.2
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• pp.103-110
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• 2010

The first morphogenetic event of preimplantation development, compaction, was required efficient production of porcine embryos in vitro. Compaction of the porcine embryo, which takes place at post 4-cell stage, is dependent upon the adhesion molecule E-cadherin. The E-cadherin through ${\beta}$-catenin contributes to stable cell-cell adhesion. Rho-associated kinase (ROCK) signaling was found to support the integrity of E-cadherin based cell contacts. In this study, we traced the effects of ROCK-1 on early embryonic development and structural integrity of blastocysts in pigs. Then, in order to gain new insights into the process of compaction, we also examined whether ROCK-1 signaling is involved in the regulation of the compaction mediated by E-cadherin of cellular adhesion molecules. As a result, real-time RT-PCR analysis showed that the expression of ROCK-1 mRNA was presented throughout porcine preimplantation stages, but not expressed as consistent levels. Thus, we investigated the blastocyst formation of porcine embryos treated with LPA and Y27632. Blastocysts formation and their qualities in LPA treated group increased significantly compared to those in the Y27632-treated group (p < 0.05). Then, to determine whether ROCK-1 associates embryonic compaction, we explored the effect of activator and/or inhibitor of ROCK-1 on compaction of embryos in pigs. The rate of compacted morula in LPA treated group was increased compared to that in the Y27632-treated group (39.7 vs 12.0%). Furthermore, we investigated the localization and expression pattern of E-cadherin at 4-cell stage porcine embryos in both LPA- and Y27632-treated groups by immunocytochemical analysis and Western blot analysis. The expression of E-cadherin was increased in LPA-treated group compared to that in the Y27632-treated group. The localization of E-cadherin in LPA-treated group was enriched in part of blastomere contacts compared to that Y27632-treated group. ROCK-1 as a crucial mediator of embryo compaction may plays an important role in regulating compaction through E-cadherin of the cell adhesion during the porcine preimplantation embryo. We concluded that ROCK-1 gene may affect the developmental potential of porcine blastocysts through regulating embryonic compaction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.96-103
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• 2000

The voice traffic is one of the most important real-time objects in WATM(Wireless Asynchronous Transfer Mode) networks. In this paper, we propose a new MAC(Medium Access'Control) protocol for the efficienttransmission of voice traffic over WATM networks in the multimedia environment and compare the performanceto existing similar protocols. The new protocol separates the reservation slot period for voice and that for data toguarantee some level of QoS(Quality of Service) in voice traffic. This is denoted by a slot assignment functiondepending on the frame size. According to the characteristics of voice traffic which is repeatedly in silent states,the protocol allocates voice reservation request slots dynamically with respect to the number of silent(off state)voice sources and also sends the first block of talkspurt restarted after silent period with a reservation requestslot to reduce the access delay.The simulation results show that the proposed protocol has better performance than Slotted Aloha in bandwidthefficiency, and can serve a certain level of QoS by the given slot assignment function even when the number ofvoice terminals varies dynamically. This means we can observe that the new MAC protocol is much better thanthe NC-PRMA(None Collision-Packet Reservation Multiple Access) protocol.

• Composites Research
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• v.28 no.4
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• pp.155-161
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• 2015

A composite structure was fabricated with embedded impact detection capabilities for applications in Structural Health Monitoring (SHM). By embedding sensor functionality in the composite, the structure can successfully perform impact localization in real time. Smart resin, composed of $Pb(Ni_{1/3}Nb_{2/3})O_3-Pb(Zr,\;Ti)O_2$ (PNN-PZT) powder and epoxy resin with 1:30 wt%, was used instead of conventional epoxy resin in order to activate the sensor function in the composite structure. The embedded impact sensor in the composite was fabricated using Hand Lay-up and Vacuum Assisted Resin Transfer Molding(VARTM) methods to inject the smart resin into the glass-fiber fabric. The electrodes were fabricated using silver paste on both the upper and bottom sides of the specimen, then poling treatment was conducted to activate the sensor function using a high voltage amplifier at 4 kV/mm for 30 min at room temperature. The composite's piezoelectric sensitivity was measured to be 35.13 mV/N by comparing the impact force signals from an impact hammer with the corresponding output voltage from the sensor. Because impact sensor functionality was successfully embedded in the composite structure, various applications of this technique in the SHM industry are anticipated. In particular, impact localization on large-scale composite structures with complex geometries is feasible using this composite embedded impact sensor.

• Journal of Embryo Transfer
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• v.32 no.3
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• pp.73-79
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• 2017

Transplantation is considered to be a very useful approach to improve human welfare and to prolong life-span. Heterologous organ transplantation using pig organs which are similar to human beings and easy to make mass-production has known as one of the alternatives. To ensure potential usage of the pig organ for transplantation application, it is essentially required to generate transgenic pig modifying immuno-related genes. Previously, we reported production of heterozygous ${\alpha}1,3$-galactosyltransferase (GalT) knock-out and human membrane cofactor protein (MCP) expressing pig ($GalT^{-MCP/+}$), which is enforced for suppression of hyperacute and acute immunological rejection. In this study, we reported generation of homozygous pig ($GalT^{-MCP/-MCP}$) by crossbreeding $GalT^{-MCP/+}$ pigs. Two female founders gave birth to six of $GalT^{-MCP/-MCP}$, and seven $GalT^{-MCP/+}$ pigs. We performed quantitative real-time PCR, western blot, and flow cytometry analyses to confirm GalT and MCP expression. We showed that fibroblasts of the $GalT^{-MCP/-MCP}$ pig do not express GalT and its product Gal antigen, while efficiently express MCP. We also showed no expression of GalT, otherwise expression of MCP at heart, kidney, liver and pancreas of transgenic pig. Taken together, we suggest that the $GalT^{-MCP/-MCP}$ pig is a useful candidate to apply xenotransplantation study.

• Journal of Veterinary Clinics
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• v.24 no.3
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• pp.295-299
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• 2007

The detrimental effects of gene transfection on embryo development and the molecular mechanism behind the differential expression of genes related to early embryo development were assessed in the production of transgenic cow embryos through somatic cell nuclear transfer (NT). Parthenogenetic, IVF, and transgenic NT embryos derived from ${\alpha}_1$-antitrypsin transfected ear fibroblast cells was produced. To investigate the molecular mechanism behind lower developmental competence of transgenic NT embryos, the differential mRNA expression of three genes ($IFN-{\tau}$, Oct4, Fgf4) in the 3 types of embryo (Parthenogenetic, IVF, transgenic NT) was examined. RNA was extracted from ten blastocysts derived from 3 types of embryos and reverse-transcripted for synthesis of the first cDNA. The quantification of 3 gene transcripts ($IFN-{\tau}$, Oct4, and Fgf4) was carried out in three replicate by quantitative real-time reverse transcriptase PCR. Expression level of $IFN-{\tau}$ mRNA was significantly higher in transgenic NT embryos than parthenogenetic and IVF embryos (P<0.05). However, expression level of Oct4 and Fgf4 of transgenic NT embryos was significantly lower than IVF embryos (P<0.05). Altered levels of these three mRNA transcripts may explain some of the embryonic/fetal/neonatal abnormalities observed in offspring from transgenic NT embryos.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.1-6
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• 2022

As the demand for wearable devices increases, many studies have been studied on the development of flexible electrode materials recently. In particular, the development of high-performance flexible electrode materials is very important for wearable sensors for healthcare because it is necessary to continuously monitor and accurately detect body information such as body temperature, heart rate, blood glucose, and oxygen concentration in real time. In this study, we fabricated the nonenzymatic glucose sensor based on polyaniline/carbon nanotube fiber (PANI/CNT fiber) electrode. PANI layer was synthesized on the flexible CNT fiber electrode through electrochemical polymerization process in order to improve the performance of a flexible CNT fiber based electrode material. Surface morphology of the PANI/CNT fiber electrode was observed by scanning electron microscopy. And its electrochemical characteristics were investigated by chronoamperometry, cyclic voltammetry, electrochemical impedance spectroscopy. Compared to bare CNT fiber electrode, this PANI/CNT fiber electrode exhibited small electron transfer resistance, low peak separation potential and large surface area, resulting in enhanced sensing properties for glucose such as wide linear range (0.024~0.39 and 1.56~50 mM), high sensitivity (52.91 and 2.24 ㎂/mM·cm²), low detection limit (2 μM) and good selectivity. Therefore, it is expected that it will be possible to develop high performance CNT fiber based flexible electrode materials using various nanomaterials.

• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.206-212
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• 2024

Purpose: This study conducted research on the sharing of information to enhance the survival rate of emergency patients by swiftly transferring them to appropriate hospitals through sharing the patients' conditions, treatment histories, and transportation information with the Maritime Police Agency and relevant agencies when emergencies occur in the marine environment. Methods: In this study, emergency patient information classified in a smartphone app was received, stored, and transmitted using the LoRa communication method by electronic triage tags, and the transmitted emergency patient information was implemented to be collected in real-time through a hybrid triage system along with LoRa receivers. Results: Through the hybrid triage system, it was possible to receive emergency patient information according to the distance or confirm delayed reception. It was observed that most data were received when the distance was short, while data reception was unsuccessful in relatively longer distances. Conclusion: It was confirmed that in mass disaster environments where internet communication is impossible, rapid and accurate understanding of casualty information at disaster sites and appropriate disaster responses can be achieved using self-networking methods such as LoRa communication. However, limitations inherent in communication methods were also recognized. Further research on various communication methods is required to collect emergency patient information and transfer them to appropriate hospitals in situations where internet communication is unavailable.

• Cartoon and Animation Studies
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• s.15
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• pp.1-12
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• 2009

As the technology realizing digital multimedia has been developing remarkably based on Internet environment, today we can gain various information we need quickly and easily without regard to time or place by using world wide web. The recent spread of digital animation as a way of communication on Internet has been forming a new communication paradigm according to the development of age. Besides, digital animations embodied on web are a kind of communication medium which is expressed through interactions using different digital multimedia tools and put the concepts of time and space together. This is a form which can cope with various forms of information, and it occupies a high rate on web and is used often. Web animations offer various forms of communication, such as interface structure design for information transfer, characters, typography, and other graphic elements, which make users feel maximized real dynamics. This paper analyzes and evaluates the categories according to the characteristics, information and usage types of digital animations used on web, examines more efficient communication expressions based on them, and pays attention to the Internet environment that will develop and change in the future. With regard to it, this research aims at suggesting a useful theory so that diverse digital animations on web based on Internet environment would develop into a new communication paradigm responding to the change of time.