• Journal of the Korean Institute of Telematics and Electronics T
• /
• v.35T no.2
• /
• pp.66-71
• /
• 1998

A compact ESP of two-stage type is widely used with positive corona discharge in working environment where the production of ozone is extreamly prohibited. Since there are few scientific reports on a compact ESP, we have investigated the fundamental characteristics of a two-stage ESP. A model two-stage ESP is made with simple structure in order to simplify theoretical analysis and the relative position of the ionizer and collector section can be changed. The experimental investigation revealed many interesting facts.: The electric field in the collector electrodes affects the corona discharge of the ionizer. The concentration of particles after collector remarkably varied in the region between the high voltage and grounded electrodes. The collection efficiency right behind the high voltage electrode is much greater than that behind the grounded one. The total collection efficiency, calculated by integrating the particle concentration in whole measuring region, is greater when the high voltage electrode of the collector is located behind the discharge electrode of ionizer. Thus, the relative position of the ionizer and collector electrodes affects the precipitation characteristics.

• Macromolecular Research
• /
• v.8 no.4
• /
• pp.179-185
• /
• 2000

Generally vascular grafts with a relatively large inner diameter (> 5 mm) have been successfully employed for replacement in the human body. However, the use of small diameter grafts is limited, because these grafts rapidly occlude due to the thrombosis. The ideal blood-contacting surface of a prosthesis would be an endothelial cell (EC) lining, because the confluent monolayer of healthy ECs that culture natural blood vessels represents the ideal nonthrombogenic surface. For vascular graft application, the stable EC adhesion on surface under How conditions is very important. In this study, the adhesive strength of ECs attached on polymer surfaces coated with collagen type IV (Col IV), fibronectin (Fn), laminin (Ln), and treated with corona was investigated onto polyurethane (PU) films. The EC-attached PU surfaces were mounted on parallel-plate flow chambers in a How system prepared for cell adhesiveness test. Three different shear stresses (100, 150, and 200 dyne/㎠) were applied to the How chambers and each shear stress was maintained for 120 min to investigate the effect of shear stress and surface treatment condition on the EC adhesion strength. It was observed that the EC adhesion strength on the surface-modified PU films was in the order of Ln≡Fn > Col IV > corona 》 control. More than 70% of the adhered cells were remained on surface-modified PU surface after applying the shear stress,200 dyne/㎠ for 2 hrs, whereas the cells were completely detached on the control PU surface within 10 min after applying the same shear stress. It seems that the type of adsorbed proteins and hydrophilicitv onto the PU surfaces play very important roles for cell adhesion strength.

• The Journal of the Korea Contents Association
• /
• v.21 no.10
• /
• pp.194-203
• /
• 2021

With the spread of Corona virus l spreading to the uncertainty of society, consumers request more active social responsibility programs. In other words, it is manifest that corporate brands are required to pursue the public interests. Consumers go beyond the corporate social responsibility programs and support corporate's involvement to solve the social problems and they consume the brand accordingly. Thus, the companies respond to the consumers' request as a form of brand activism, or the new social marketing form in which the companies set the brand as an individual and seek the solutions of social issues. In this study, five experienced experts in the area were recruited to conduct in-depth interviews and how brand activism was practiced worldwide. The results reveal that brand activism is actively practiced with the support of consumers in the area of support for the small business, anti-racism efforts, gender diversity and equality, and sustainability.

• Communications of Mathematical Education
• /
• v.35 no.3
• /
• pp.341-358
• /
• 2021

Corona, which first broke out in 2020, has caused many changes in many parts of society. Education was not an exception to this change. Teachers had to prepare online classes and students were asked to participate in it without sufficient preparation. Regarding online learning, many studies, in the field of developing teaching module and material or observing the satisfaction of online class, were conducted but there was no study based on how online class is happening in school. Therefore, this study was to investigate the current situation and satisfaction of online class for high school students and explored the relationship between sub-elements of mathematics learning and the level of satisfaction of online learning. As a result, mathematics online class was generally conducted in the form of real-time interactive classes and students felt a little satisfied with it. However, some conflicting opinions were expressed on the continuation of mathematics online learning. In addition, the study found that the higher level of satisfaction students have with online class, the difference appears in the sub-elements of learning mathematics such as values of mathematics, and motivation to learn, willingness to learn mathematics, learning strategies according to the safisfactory level of online class.

• Journal of Christian Education in Korea
• /
• v.72
• /
• pp.7-24
• /
• 2022

Christian education for the world after COVID-19 needs to use rapid changes in the surrounding situation as an opportunity to overcome a new crisis so that the church can achieve its educational mission. If the biggest dilemma in the post-Corona era is that there is no authoritative educational prescription anywhere, the most reasonable option for church education in this situation is to emphasize and cultivate learners' ability to flexibly cope with rules that are completely different than before COVID-19. As a natural result of the crisis, Christian education needs to be more interested in the trend of social change in the pandemic era(glocalization, digital transformation, economic inequality, educational environment change, church crisis) and actively reflect its contents in education. In addition, while operating a mobile(or online) church school that combines offline and online, there is an urgent need for an innovative transition to a core church school where certain church schools and churches cooperate with each other, a church school that guarantees a safe learning space, and an ecological church school that is interested in education dealing with climate change and ecology.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.19 no.7
• /
• pp.39-44
• /
• 2005

A great part of flint fuel is Hydrogen and carbon's combination, they should be generated steam and carbon gas when combine with oxygen for perfect combustion in the inside of engine but, the pollutive material are discharged, even though perfect combustion condition especially $NO_x$ and Smoke. they are really harmful for health. In this paper was shown the result of discharging gas' reduction quality. which used combination of corona discharge using the high voltage source of common frequency with EGR. $NO_x$ is increased in entire load erea in proportion to increasing of EGR rate and impression voltage. Smoke is increased slowly under 75[%] in load rate but it is increased rapidly in entire load erea and the reduction rate of Smoke is increased in proportion to increasing of impression voltage.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.48 no.3
• /
• pp.215-220
• /
• 1999

$SO_2$and CO gas removal characteristics of a wire-to-cylinder type nonthermal discharge plasma reactor in various applied voltage (-dc, ac, fast rising pulse and high frequency pulse) and a crossed dc magnetic field have been investigated. The experiment has been emphasized on the oxidizing characteristics of $SO_2$ and CO gas by $O_3$ and the applying of a crossed magnetic field, which would induce the cyclotronic and drift motions of electrons making the residual time longer in the removal airgap space. And it also would enhance the energy of electrons and the electrophysicochemical actions to remove the pollutant gases effectively. It is found thatthe corona onset voltage and the breakdown voltage were decreased with increasing the crossed magnetic field and decrease initial fed $SO_2$and CO concentration. As a result, a higher ozone generation and $SO_2$ and CO gas removal rate of 20[%] can be obtained with -dc, ac and fast rising pulse corona discharges in the crossed dc current-induced magnetic field. But high frequency pulse didn't show effect in applying of a crossed magnetic field.

• Journal of IKEEE
• /
• v.24 no.1
• /
• pp.293-301
• /
• 2020

Consultation with the patient and doctor is very important in the examination. However, if the consultation cannot be done directly, such as corona virus, it is difficult for the doctor to determine the patient's condition more accurately. Recently, an image counseling system has been developed based on the Internet, but in the case of heart disease, remote medical counseling cannot be performed because it is not possible to stethoscope the heart sounds remotely. In order to solve this problem, it is necessary to develop an interactive mobile robot capable of remote medical consultation, and a doctor and a patient should be able to set a planting sound during consultation and transmit it in real time. In this paper, we developed a robot that can remotely control a medical counseling robot to move to a hospital room where patients are hospitalized, and to consult a patient in the room remotely from a doctor's office. A remote medical imaging stethoscope system for real-time heart sound transmission is presented. The proposed system is a kind of P2P communication that transmits video information, audio information, and control signal independently through webRTC platform, so that there is no data loss. Consults and sees doctors in real time and finds it more effective than traditional methods for patient security. The system implemented in this paper will be able to perform remote medical care in the place where the spread of diseases between humans like the recent corona 19 as well as the remote medical care of heart disease patients in the future.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.1936-1938
• /
• 2000

In this paper, a frequency spectra of AE (acoustic emission) signals detected from the partial discharges of an epoxy resin void and a cast resin transformer in operating were analyzed to offer the proper frequency range of AE signals from the corona discharge for the purpose of AE sensor selection, From these results, a frequency spectra of AE signals emitted from the corona discharges in the void of an epoxy resin sample were about 190[kHz] to 220[kHz] by the FFT(fast fourier transform), A frequency spectra of AE signals emitted from a cast. resin transformer with non-load were appeared to be downward of about 140[kHz] by the FFT, and then a frequency spectra of AE signals emitted from the above of cast resin transformer with load were appeared to increase from about 190[kHz] to 220[kHz] by the FFT.

• Bulletin of the Korean Space Science Society
• /
• 2010.04a
• /
• pp.38.3-39
• /
• 2010

While major solar proton events (SPEs) come from the coronal mass eject (CME)-driven shocks in solar wind, there are many evidences that potentiality of CMEs to generate SPEs depends on its early evolution near the Sun and on different solar activities observed around the CME liftoff time. To decipher origin of SPE release, we have investigated onset time comparison of the SPE with CME, metric type II radio burst, and hard X-ray flare. For this, we select 30 SPEs observed from 1997 to 2006 by using the particle instrument ERNE onboard SOHO, which allows proton flux anisotropy measurement in the energy range ~10 - 50MeV. Onset time of the SPEs is inferred by considering the energy-dependent proton transport time. As results, we found that (1) SPE onset time is comparable to that of type II but later than type III onset time and HXR start time, (2) SPE onset time is mostly later than the peak time of HXR flare, (3) almost half of the SPE onsets occurred after the HXR emission, and (4) there are two groups of CME height at the onset time of SPE; one is the height below 5 Rs (low corona) and the other is above 5Rs (high corona). In this talk, we will present the onset time comparison and discuss about the origin of the SPE onset.