• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.2
• /
• pp.61.1-61.1
• /
• 2011

We have performed simultaneous observations at 22GHz and 43GHz on AGNs hosted by elliptical galaxies using KVN radio telescope. We have constructed the sample, based on two major surveys in radio and optical band, i.e. Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) and Sloan Digital Sky Survey (SDSS) DR7, respectively. We restricted the redshift range 0.01 < z < 0.06 and the absolute magnitude Mr < -19.4 in order to satisfy volume limited sample. We also checked clear detection of four distinctive emission lines ([NII], [OIII], $H{\alpha}$, $H{\beta}$) so as to utilize on BPT diagram, distinguishing AGNs from star-forming galaxies. Elliptical galaxies have been selected by visual inspection making use of SDSS optical images. Then, we cross-matched the elliptical galaxies with FIRST detections. About 35% of the galaxies have been detected throughout KVN observations. We derive spectral index, applying the flux of different radio frequencies from FIRST (1.4GHz) and KVN (22GHz) and classify into steep, flat or inverted spectrum. We have found that most of the detected galaxies have flat spectrum while the rest of them have steep spectrum. This implies that a number of detected galaxies might have compact structure associated with the central region of the galaxies. The relation between black hole mass and radio luminosity has shown relatively tighter correlation in high frequency than in low frequency, which confirms that high frequency in radio band is appropriate to study the center of the galaxies.

• Journal of the Korea Society of Computer and Information
• /
• v.11 no.2 s.40
• /
• pp.75-82
• /
• 2006

The service use management for keeping up stable and effective environment is hard little by little by according to increase of internet user and being complicated network environment of the Internet little by little. being various of the requirements of the service which is provided and the user demand. And the beginning flag security was limited in IDS, But recently the integrated civil management is coming to be considered seriously according to adventting IDS. Firewall , Security or system. The development of integrated security civil management system to analyze widely through observation and detection at Network or host base, the judgment of attack, and integrated analysis of infiltration information is necessary because of detecting the various type attack.

• Food Science of Animal Resources
• /
• v.39 no.6
• /
• pp.934-942
• /
• 2019

Previous studies on dry aged beef, which substantially increases the value of low-grade raw beef and non-preferred cuts, are currently limited to the observation of aged beef changes in laboratory settings or under particular aging conditions, whereas the factors influencing aging have so far been underexplored. Herein, we attempt to establish a technique for distinguishing between fresh and aged beef by observing changes in quality during beef aging. Specifically, we analyzed the effect of time on the quality of aged beef sourced from three Korean manufacturers and identified quality indicators that can be used to distinguish between fresh and aged beef, regardless of supplier. Storage/trimming/aging/cooking losses, moisture/fat/protein/collagen contents, and water holding capacity were tested as potential indicators, among other parameters. As a result, the quality of dry aged beef was shown to be supplier-dependent, which made the identification of factors for the above origin-independent discrimination difficult. Nevertheless, as storage loss, water holding capacity, and cooking loss significantly changed with dry aging time in all cases, these parameters were concluded to be potentially suited for discrimination purposes. The insights gained in this work may help promoting further research in this field and contribute to the development of a standard for consistent aged beef production.

• Journal of Astronomy and Space Sciences
• /
• v.34 no.4
• /
• pp.303-314
• /
• 2017

With increased human activity in space, the risk of re-entry and collision between space objects is constantly increasing. Hence, the need for space situational awareness (SSA) programs has been acknowledged by many experienced space agencies. Optical and radar sensors, which enable the surveillance and tracking of space objects, are the most important technical components of SSA systems. In particular, combinations of radar systems and optical sensor networks play an outstanding role in SSA programs. At present, Korea operates the optical wide field patrol network (OWL-Net), the only optical system for tracking space objects. However, due to their dependence on weather conditions and observation time, it is not reasonable to use optical systems alone for SSA initiatives, as they have limited operational availability. Therefore, the strategies for developing radar systems should be considered for an efficient SSA system using currently available technology. The purpose of this paper is to analyze the performance of a radar system in detecting and tracking space objects. With the radar system investigated, the minimum sensitivity is defined as detection of a $1-m^2$ radar cross section (RCS) at an altitude of 2,000 km, with operating frequencies in the L, S, C, X or Ku-band. The results of power budget analysis showed that the maximum detection range of 2,000 km, which includes the low earth orbit (LEO) environment, can be achieved with a transmission power of 900 kW, transmit and receive antenna gains of 40 dB and 43 dB, respectively, a pulse width of 2 ms, and a signal processing gain of 13.3 dB, at a frequency of 1.3 GHz. We defined the key parameters of the radar following a performance analysis of the system. This research can thus provide guidelines for the conceptual design of radar systems for national SSA initiatives.

• Restorative Dentistry and Endodontics
• /
• v.25 no.3
• /
• pp.459-473
• /
• 2000

Dental caries is the most common disease in the maxillofacial area. There are many factors contributing to its development, but complete understanding and prevention is not fully known. Since the structure of the coronal and root portion of the tooth is different, the remineralization and demineralization process is also known to be different. In this study, by using a partially saturated buffer solution, we created artificial enamel and dentin caries and evaluated mineral loss. A remineralization solution with four different degrees of saturation (degree of saturation ; group 1, 0.268, group 2, 0.309, group 3, 0.339, group 4, 0.390, PH 4.3, F-2ppm) was used on a demineralized specimen. The mineral precipitating quantity and depth was evaluated by using microradiography. Using an atomic force microscope (AFM), hydroxyapatite crystals of normal, demineralized, and remineralized enamel and dentin were evaluated. The results were as follows: 1. As the degree of saturation of the remineralizing solution increased, the mineral precipitation in the enamel was increased. In group 4, mineral precipitation was limited near the surface. 2. As the degree of saturation of the remineralizing solution increased, the mineral precipitation in the dentin was decreased and it occurred in a deeper portion. In group 4, however, mineral precipitation occurred on the surface and its quantity increased. 3. There was a statistically significant interaction between enamel and dentin mineral content changes on specimens treated with remineralization and demineralization solution (demineralization r=0.44, remineralization r=0.44, p<0.05). 4. Demineralized hydroxyapatite crystals showed central and peripheral dissolving and widening of intercrystal spaces under the AFM. 5. In dentin remineralization small crystal precipitation occurred between the large crystals. We conclude that by adjusting acidulated buffer solution's degree of saturation, we can control enamel and dentin remineralization. In addition, the AFM is highly useful in evaluating changes in remineralized and demineralized hydroxyapatite crystals.

• The Journal of Society for e-Business Studies
• /
• v.16 no.4
• /
• pp.97-108
• /
• 2011

Small IT service organizations operate their business with limited resources and workforce in comparison with large enterprises, and they could be categorized in various types based on the method of value creation. But the recent studies on information security have been conducted and they were focused on the construction of general information security countermeasure, without considering size of the business and characteristic. Hence we have undergone the process of classifying information assets. Then we extracted and categorized the information assets considering characteristics of small organization's size and business process. Specifically we have classified the information assets according to business scenario design through qualitative observation method. Then we have validated the classified information assets by utilizing statistical method. We may anticipate that this study results could be basic data for developing the differentiated information security countermeasures for small IT service organization.

• Journal of Korean Home Economics Education Association
• /
• v.9 no.2
• /
• pp.87-100
• /
• 1997

The purpose of this study were to investigate and no investigate and to compare perceptions of home economics teachers and educators regarding home economics student teaching pratice, thereby to provide fundamental information for improving home economics student teaching pratice. The specific objectives of this study were at follows. 1. To determine and compare the perceptions of home economics teachers and teacher educators regarding the importance and achievement of (1) the objectives of student teaching, (2) the experiences of student teaching, (3) procedures for selecting cooperating teachers, (4) roles and responsibilities of cooperating teachers, and (5) roles and responsibilities of university supervisors. 2. To identify problems and revisions about home economics student teaching pratice suggested by home economics teachers and teacher educators. The subjects in this study included 90 home economics teachers in 500 girls’middle schools and 13 teacher educators in 21 universities with home economics education department in Korea. For this study, the Habedi’s instruments were used through testing validity and reliability. The data of this study were analyzed by using mean, standard deviation, t-test, and content analysis. The results of this study were as follow；1. The areas with the difference of perceptions of the importance between the two groups were objectives of student teaching, experiences of student teaching, procedures for selecting cooperating teachers, and roles and responsibilities of cooperating teachers. 2. Regarding problems about home economics students teaching practice, home economics teachers indicated difficulty in performing adequate student teaching because of reduction in class hours, and lack of student teachers’positive attitude in performing student teaching, while teacher educators indicated having reluctancy of cooperating school to admit student teachers, and difference in experiences of student teachers because of disparity among cooperating schools. As solutions about the problems of home economics student teaching practice, home economics teachers suggested that student teaching course should be limited to the students qualified for teaching and that class observation and teaching practice in real class should be emphasized, while teacher educators suggested that student teaching should be performed adequately by providing institutions to control student teaching practice teacher should be made efficient by examining the scales of cooperating schools.

• Journal of Korean Critical Care Nursing
• /
• v.11 no.1
• /
• pp.46-66
• /
• 2018

Purpose : The purpose of this study was to systematically review the instruments utilized to assess physical impairment in post-intensive care syndrome (PICS) of intensive care unit (ICU) survivors. Method : Online databases searched were MEDLINE, Cochrane, CINAHL, and Embase. Studies that met the following criteria were included: 1) the study population exclusively had experience with ICU admission; 2) the study assessed pulmonary, neuromuscular, and physical functions; and 3) the study was published in English language journals after 2007. Results : A total of 56 instruments (2 pulmonary, 25 neuromuscular, 29 physical function) from 94 studies were reviewed. They were classified into self-report, observation, and measurement according to the type of assessment. No instrument measured all 3 areas of physical impairment. Five instruments were originally developed for the ICU patients. The most frequently applied instruments were the Medical Research Council and the 36-item Short Form Survey (physical component summary), which were used in 23 studies each. Only 13.8% of reviewed studies reported the reliability or validity of the instruments. Conclusion : Our results suggest that the appropriateness of instruments assessing physical impairment in PICS cannot be guaranteed. Despite the multidimensional concept of physical disabilities, most studies measured only one area, and studies that reported psychometric properties were limited. Accordingly, we propose to develop a unique and multifaceted instrument for ICU survivors.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.8
• /
• pp.815-823
• /
• 2011

Combustion phenomena in porous media combustors are widely used in industrial fields for the combustion of lowgrade fuels and the regeneration of combustion heat. However, studies of combustion phenomena in porous media have been limited, because these phenomena are difficult to observe, and the configurations of porous media are complex. We propose a simple model combustor: a multi-channel combustor that consists of many layers of combustion channels made of quartz plates. We conducted an experimental observation of the flames in the multi-channel combustor and obtained experimental results for the flame stabilization limits. Flames formulated in the multi-channel combustor showed variation in the spatial distribution depending on the heat transfer between neighboring channels. A simple analytical model was developed and the variation in the flammability limits of the multi-channel combustor was discussed. This study will enhance our understanding of flame behavior in a porous-media combustor.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.30 no.6
• /
• pp.540-545
• /
• 2008

Since mid 20th century, dental treatments with laser have been introduced and improved a lot. Because early $CO_2$, Nd:YAG, diode, argon, and holmium lasers are used for dealing soft tissue, so it applied just limited field. But, in 1997 the lasers of erbium family that able to dealing soft and hard tissue also were introduced, laser application fields are enlarged. In today, the application fields reach on implantation treatment, so clinicians can use the laser to make holes for implantation, and flap elevation, even though treating peri-implantitis. So our class want to discover the optimal setting of Er:YAG laser when treating peri-implantitis. We observed the surface that initially treated by RBM and TPS passion and laser with varied options of exposure time and power with SEM image. For this we conclude the optimal setting range that does not alter the implant surface structure and report it.