• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.559-563
• /
• 2015

Monitor of All-sky X-ray Image (MAXI) is a Japanese X-ray all-sky surveyer mounted on the International Space Station (ISS). It has been scanning the whole sky since 2009 during every 92-minute ISS rotation. X-ray transients are quickly found by the real-time nova-search program. As a result, MAXI has issued 133 Astronomer's Telegrams and 44 Gamma-ray burst Coordinated Networks so far. MAXI has discovered six new black holes (BH) in 4.5 years. Long-term behaviors of the MAXI BHs can be classified into two types by their outbursts; a fast-rise exponential-decay type and a fast-rise flat-top one. The slit camera is suitable for accumulating data over a long time. MAXI issued a 37-month catalog containing 500 sources above a ~0.6 mCrab detection limit at 4-10 keV in the region ${\mid}{b}{\mid}$ > $10^{\circ}$. The SSC instrument utilizing an X-ray CCD has detected diffuse soft X-rays extending over a large solid angle, such as the Cygnus super bubble. MAXI/SSC has also detcted a Ne emission line from the rapid soft X-ray nova MAXI J0158-744. The overall shapes of outbursts in Be X-ray binaries (BeXRB) are precisely observed with MAXI/GSC. BeXRB have two kinds of outbursts, a normal outburst and a giant one. The peak dates of the subsequent giant outbursts of A0535+26 repeated with a different period than the orbital one. The Be stellar disk is considered to either have a precession motion or a distorted shape. The long-term behaviors of low-mass X-ray binaries (LMXB) containing weakly magnetized neutron stars are investigated. Transient LMXBs (Aql X-1 and 4U 1608-52) repeated outbursts every 200-1000 days, which is understood by the limit-cycle of hydrogen ionization states in the outer accretion disk. A third state (very dim state) in Aql X-1 and 4U 1608-52 was interpreted as the propeller effect in the unified picture of LMXB. Cir X-1 is a peculiar source in the sense that its long-term behavior is not like typical LMXBs. The luminosity sometimes decreases suddenly at periastron. It might be explained by the stripping of the outer accretion disk by a clumpy stellar wind. MAXI observed 64 large flares from 22 active stars (RS CVns, dMe stars, Argol types, young stellar objects) over 4 years. The total energies are $10^{34}-10^{36}$ erg $s^{-1}$. Since MAXI can measure the spectrum (temperature and emission measure), we can estimate the size of the plasma and the magnetic fields. The size sometimes exceeds the size of the star. The magnetic field is in the range of 10-100 gauss, which is a typical value for solar flares.

• Journal of Periodontal and Implant Science
• /
• v.27 no.3
• /
• pp.495-514
• /
• 1997

The purpose of this study was to evaluate the in vitro effects of Nd:YAG laser irradiation on removal of a root surface smear layer after root planing in comparison with Tetracycline HCl. The 60 extracted human teeth due to severe periodontal disease were vigorously scaled and root planed with Gracey curet. Thirty specimen($5{\times}5{\times}2mm$) were obtained from root planed surface of 30 human teeth and assigned randomly to one of three groups : root planed group(5 specimen), Tetracycline HCI group(5 specimen, burnished for 5 minutes), and Nd:YAG laser group(25 specimen, German Dental Laser, Fotona Twinlight). Nd:YAG laser group was divided into 4 subgroups according to power of 1W, 1.5W, 2W, 3W at frequency to 10Hz. The specimen were then fixed, and examed by Scanning electron microscopic study. 30 of 60 human teeth used to measurement of the intrapulpal temperature rise during laser irradiation. Laser-irradiated surface exhibited various surface texture from relative flat surface to irregular surface with patent dentinal tubules of various shape and size. In some area, the root surface alteration which are carbonization, pit and crater formation and melting and resolidification were observed. The number of exposed dentinal tubules per unit($100_{\mu}m^2$) on tetracycline HCI group was more than that in the laser group below 1.5W of power(150mJ/pulse) and was significantly less than that in laser group above 2W of power(200mJ/pulse)(P<0.OOl). As power increased the intrapulpal temperature rise also increased. The result suggested that the parameter which effectively remove root surface smear layer than tetracycline HCI may cause thermal damage to pulp and root surface alteration result from laser exposure would indicate need for additional instrumentation. Thus, Nd:YAG laser irradiation in these parameter may not be appropriate for clinical use as adjunct to conventional periodontal therapy.

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 1981.05a
• /
• pp.39.1-39
• /
• 1981

The author presents clinical study for 111 cases of tinnitus with pure tone audiometry from Jan. 1, 1978 to Dec. 31, 1980 in department of otolaryngology, Ewha Womans University Hospital. The results were as follows; 1) Male to Female ratio was as 1 : 1, and peak age incidence was in the age group of 21 to 30. 2) Most frequent duration was 1 month to 1 year in the cases of the tinnitus. 3) The patient who complained tinnitus only was 10.0% and the patient who complained tinnitus with hearing impairment was 72.0% in the cases of tinnitus. 4) The affected site in the tinnitus, in order of frequency were; Both ear 38.7% Left ear 32.4% Right ear 28.9% 5) The drum finding, in order frequency were; Normal 48.0% Retraction 33.1% Perforation 8.4% 6) The degree of hearing loss in the audiometry were; Normal 29.2% Moderate severe 22.7% 7) The shape of hearing impairments were; High tone loss 46.9% Flat 33.0% Low tone loss 11.9% 8) The occurrence of $C_{5}$ dip was 11.0% in cases of the tinnitus. 9) The classification of hearing loss were; Sensorineural hearing loss 46.9% Mixed hearing loss 33.1 % Conductive hearing loss 20.1%

• Journal of Energy Engineering
• /
• v.25 no.2
• /
• pp.1-20
• /
• 2016

A condensation heat transfer model is very important for the safety analysis of nuclear power plants. Especially, condensation under the presence of noncondensable gases (NCGs) is an important issue in nuclear safety because the presence of even a small quantity of NCGs in the vapor largely reduces the condensation rate. In this study, the condensation heat transfer model of the severe accident analysis code MELCOR 1.8.6 has been assessed using a set of condensation experiments performed under the thermal-hydraulic conditions similar to those inside a containment during design-basis accidents or severe accidents. Experiment conditions are categorized into 4 types according to the shape of the condensation surface: vertical flat plates, outer surface of vertical pipes, inner surface of vertical pipes, the inner surface of horizontal pipes. The results of the calculations show that the MELCOR code generally under-predicts the condensation heat transfer except the condensation on inner surface of vertical pipes.

• Radiation Oncology Journal
• /
• v.20 no.3
• /
• pp.274-282
• /
• 2002

Purpose : Measurement of transmission dose is useful for in vivo dosimetry. In this study, the algorithm for estimating the transmission dose for open radiation fields was modified for application to partially blocked radiation fields. Materials and Methods : The beam data was measured with a flat solid phantom with various blocked fields. A new correction algorithm for partially blocked radiation field was developed from the measured data. This algorithm was tested in some settings simulating clinical treatment with an irregular field shape. Results : The correction algorithm for the beam block could accurately reflect the effect of the beam block, with an error within ${\pm}1.0\%$, with both square fields and irregularly shaped fields. Conclusion : This algorithm can accurately estimate the transmission dose in most radiation treatment settings, including irregularly shaped field.

• Korean Journal of Remote Sensing
• /
• v.23 no.2
• /
• pp.131-135
• /
• 2007

The tidal channel is influenced by sediment type, grain size, grain composition and tidal currents in tidal flat. The development of tidal channel including density, shape and order can be used to analyze the characteristics of tidal channel. The quantitative investigation to the tidal channel is insufficiency. In this paper, we represented the fractal analysis method according to the quantitatively analysis in tidal channel and compared with the different intertidal channel patterns. The tidal channel was extracted from the IKONOS image of the southern part of the Kanghwa-do. We used the Box-counting method to estimate fractal dimensions for each tidal channel. As a result, the fractal dimension values (D) were 1.31 in the southern Kanghwa-Do. Linear pattern and less dense channel development area had low D values (from 1.0563 to 1.0672). Dendritic pattern and dense channel development area had high D values (from 1.2550 to 1.3016). In other words, fractal dimension values had difference about 0.2 values according to the characteristic of tidal channel development. We concluded that fractal analysis can be able to quantitatively classification in tidal channel.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.26 no.5
• /
• pp.191-202
• /
• 2022

Markov envelope as a theoretical solution of the parabolic wave equation with Markov approximation for the von Kármán type random medium is studied and approximated with the convolution of two probability density functions (pdf) of normal and gamma distributions considering the previous studies on the applications of Radiative Transfer Theory (RTT) and the analysis results of earthquake records. Through the approximation with gamma pdf, the constant shape parameter of 2 was determined regardless of the source distance r_o. This finding means that the scattering process has the property of an inhomogeneous single-scattering Poisson process, unlike the previous studies, which resulted in a homogeneous multiple-scattering Poisson process. Approximated Markov envelope can be treated as the normalized mean square (MS) envelope for ground acceleration because of the flat source Fourier spectrum. Based on such characteristics, the path duration is estimated from the approximated MS envelope and compared to the empirical formula derived by Boore and Thompson. The results clearly show that the path duration increases proportionately to r_o^1/2-r_o², and the peak value of the RMS envelope is attenuated by exp (-0.0033r_o), excluding the geometrical attenuation. The attenuation slope for r_o≤100 km is quite similar to that of effective attenuation for shallow crustal earthquakes, and it may be difficult to distinguish the contribution of intrinsic attenuation from effective attenuation. Slowly varying dispersive delay, also called the medium effect, represented by regular pdf, governs the path duration for the source distance shorter than 100 km. Moreover, the diffraction term, also called the distance effect because of scattering, fully controls the path duration beyond the source distance of 300 km and has a steep gradient compared to the medium effect. Source distance 100-300 km is a transition range of the path duration governing effect from random medium to distance. This means that the scattering may not be the prime cause of peak attenuation and envelope broadening for the source distance of less than 200 km. Furthermore, it is also shown that normal distribution is appropriate for the probability distribution of phase difference, as asserted in the previous studies.

• The Journal of the Acoustical Society of Korea
• /
• v.40 no.6
• /
• pp.615-625
• /
• 2021

Prior to proposing appropriate standard for subway station platform, this study conducted field measurements to examine characteristics of room acoustics on platform of two subway stations. As a result of analyzing the longitudinal length of the platform, Sound Pressure Level (SPL) decreased (maximum difference : 14 dB), Reverberation Time (RT) tended to increase (maximum difference of 0.8 s ~ 1.5 s), and C50 and D50 were decreased (maximum difference: 5.9 dB ~ 9.1 dB and 31.8 % ~ 37.6 %, respectively) as measurement positions moved away from the sound source. The Interaural Cross-correlation Coefficient (IACC) did not show clear tendency, but it was lower than 0.3 in entire points. It is judged that the subway platform has non-uniform sound field characteristics due to various combinations of direct and reflective sound even though it is finished with a strong reflective material.This indicates that the room acoustic characteristics of the near and far sound field are clearly expressed depending on the source-receiver distances in the subway platform having a long flat shape with a low height compared to the length.Therefore, detailed architectural and electric acoustic design based on the characteristics of each location of speaker and sound receiver in the platform is required for an acoustic design with clear sound information at all positions of the platform.

• Journal of Broadcast Engineering
• /
• v.28 no.1
• /
• pp.79-89
• /
• 2023

A multi-view display is regarded as the most practical technology to provide a three-dimensional effect to a viewer because it can provide an appropriate viewpoint according to the observer's position. But, most multi-view displays with flat shapes have a disadvantage in that a viewer watches 3D images only within a limited front viewing angle. In this paper, we proposed a spherical display using a ball lens with spherical symmetry that provides perfect parallax by extending the viewing zone to 360 degrees. In the proposed system, each projection lens is designed to be packaged into a small modular array, and the module array is arranged in a spherical shape around a ball lens to provide vertical and horizontal parallax. Through the applied optical module, the image is formed in the center of the ball lens, and 3D contents are clearly imaged with the size of about 0.65 times the diameter of the ball lens when the viewer watches them within the viewing window. Therefore, the feasibility of a 360-degree full parallax display that overcomes the spherical aberration of a ball lens and provides a wide field of view is confirmed experimentally.

• Journal of the Korean Society of Costume
• /
• v.4
• /
• pp.87-114
• /
• 1981

A costume reveals the social characteristics of the era in which it is worn, thus we can say that the history of change of the costume is the history of change of the living culture of the era. Since the Three States era, the costume structure of this country had been affected by the costume system of the China's historical dynasties in the form of the grant therefrom because of geographical conditions, which affection was conspicuous for the bureaucrat class, particularly including but not limited to the Kings' familities. Such a grant of the costume for the bureaucrat class (i.e., official uniform) was first given by the Dang-dynasty at the age of Queen Jinduck, the 28th of the Shilla-dynasty. Since then, the costume for the bureaucrats had consecutively been affected as the ages had gone from the unified Shilla, to the Koryo and to the Yi-dynasty. As the full costumes officially used by government officials (generally called "Baek Gwan") in the Yidynasty, there existed Jo-bok, Gong-bok and Sang-bok. Of such official costumes, Gong-bok was worn at the time of conducting official affairs of the dynasty, making a respectful visit for the expression of thanks or meeting diplomatic missions of foreign countries. It appears no study was made yet with regard to the Gong-bok while the studies on the Jo-bok and the Sangbok were made. Therefore, this article is, by rendering a study and research on the styles of costumes of civil servants' stone images erected at the Kings' tombs of the Yi-dynasty, to help the persons concerned understand the Gong-bok, one of the official costume for Baek Kwan of that age and further purports to specifically identify the styles and changes of the Gong-bok, worn by Baek Gwan during the Yi-dynasty, consisting of the Bok-doo (a hat, four angled and two storied with flat top), Po (gown), Dae (belt), and Hol (small and thin plate which was officially held by the government officials in hand, showing the courtesy to and writing brief memorandums before the King) and Hwa (shoes). For that purpose, I investigated by actually visiting the tombs of the Kings of the Yi-dynasty including the Geonwon-neung, the tomb of the first King Tae-jo and the You-neung, the tomb of the 27th King Soon-jong as well as the tombs of the lawful wives and concubines of various Kings, totalling 29 tombs and made reference to relevant books and records. Pursuant. to this study, of the 29 Kings' tombs the costume styles of civil servants' stone images erected at the 26 Kings' tombs are those of Gong-bok for Baek-gwan of the Yi-dynasty wearing Bok-doo as a hat and Ban-ryeong or Dan-ryenog Po as a gown with Dae, holding Hol in hand and wearing shoes. Other than those of the 26 tombs, the costume styles of the Ryu-neung, the tomb of the Moon-jo who was the first son of 23rd King Soon-jo and given the King's title after he died and of the You-neung, the tomb of the 27th King Soon-jong are those of Jobok with Yang-gwan (a sort of hat having stripes erected, which is different from the Bok-doo), and that of the Hong-neung, the tomb of the 26th King Go-jong shows an exceptional one wearing Yang-gwan and Ban-ryeong Po ; these costume styles other than Gongbok remain as the subject for further study. Gong-bok which is the costume style of civil servants' stone images of most of the Kings' tombs had not been changed in its basic structure for about 500 years of the Yi-dynasty and Koryo categorized by the class of officials pursuant to the color of Po and materials of Dae and Hol. Summary of this costume style follows: (1) Gwan-mo (hat). The Gwan-mo style of civil servants' stone images of the 26 Kings' tombs, other than Ryu-neung, Hong-neung and You-neung which have Yang-gwan, out of the 29 Kings' tombs of the Yi-dynasty reveals the Bok-doo with four angled top, having fore-part and back-part divided. Back part of the Bok-doo is double the fore-part in height. The expression of the Gak (wings of the Bokdoo) varies: the Gyo-gak Bok-doo in that the Gaks, roundly arisen to the direction of the top, are clossed each other (tombs of the Kings Tae-jong), the downward style Jeon-gak Bok-doo in that soft Gaks are hanged on the shoulders (tombs of the Kings Joong-jong and Seong-jong) and another types of Jeon-gak Bok-doo having Gaks which arearisen steeply or roundly to the direction of top and the end of which are treated in a rounded or straight line form. At the lower edge one protrusive line distinctly reveals. Exceptionally, there reveals 11 Yang-gwan (gwan having 11 stripes erected) at the Ryu-neung of the King Moon-jo, 9 Yang-gwan at the Hong-neung of the King Go-jong and 11 Yang-gwan at the You-neung of the King Soon-jong; noting that the Yang-gwan of Baek Kwan, granted by the Myeong-dynasty of the China during the Yi-dynasty, was in the shape of 5 Yang-gwan for the first Poom (class) based on the principle of "Yideung Chaegang" (gradual degrading for secondary level), the above-mentioned Yang-gwans are very contrary to the principle and I do not touch such issue in this study, leaving for further study. (2) Po (gown). (a) Git (collar). Collar style of Po was the Ban-ryeong (round collar) having small neck-line in the early stage and was changed to the Dan-ryeong (round collar having deep neck-line) in the middle of the: dynasty. In the Dan-ryeong style of the middle era (shown at the tomb of the King Young-jo); a, thin line such as bias is shown around the internal side edge and the width of collar became wide a little. It is particularly noted that the Ryu-neung established in the middle stage and the You-neung in the later stage show civil servants in Jo-bok with the the Jikryeong (straight collar) Po and in case of the Hong-neung, the Hong-neung, the tomb of the King Go-jong, civil servants, although they wear Yang-gwan, are in the Ban-ryeong Po with Hoo-soo (back embroidery) and Dae and wear shoes as used in the Jo-bok style. As I could not make clear the theoretical basis of why the civil servants' costume styles revealed, at these tombs of the Kings are different from those of other tombs, I left this issue for further study. It is also noted that all the civil servants' stone images show the shape of triangled collar which is revealed over the Godae-git of Po. This triangled collar, I believe, would be the collar of the Cheomri which was worn in the middle of the Po and the underwear, (b) Sleeve. The sleeve was in the Gwan-soo (wide sleeve) style. having the width of over 100 centimeter from the early stage to the later stage arid in the Doo-ri sleeve style having the edge slightly rounded and we can recognize that it was the long sleeve in view of block fold shaped protrusive line, expressed on the arms. At the age of the King Young-jo, the sleeve-end became slightly narrow and as a result, the lower line of the sleeve were shaped curved. We can see another shape of narrow sleeve inside the wide sleeve-end, which should be the sleeve of the Cheom-ri worn under the Gong-bok. (c) Moo. The Moo revealed on the Po of civil servants' stone images at the age of the King Sook-jong' coming to the middle era. Initially the top of the Moo was expressed flat but the Moo was gradually changed to the triangled shape with the acute top. In certain cases, top or lower part of the Moo are not reveald because of wear and tear. (d) Yeomim. Yeomim (folding) of the Po was first expressed on civil servants' stone images of the Won-neung, the tomb of the King Young-jo and we can seemore delicate expression of the Yeomim and Goreum (stripe folding and fixing the lapel of the Po) at the tomb of the Jeongseong-wanghoo, the wife of the King Young-jo, At the age of the King Soon-jo, we can see the shape of Goreum similar to a string rather than the Goreum and the upper part of the Goreum which fixes Yeomim was expressed on the right sleeve. (3) Dae. Dae fixed on the Po was placed half of the length of Po from the shoulders in the early stage. Thereafter, at the age of the King Hyeon-jong it was shown on the slightly upper part. placed around one third of the length of Po. With regard to the design of Dae, all the civil servants' stone images of the Kings' tombs other than those of the Geonwon-neung of the King Tae-jo show single or double protrusive line expressed at the edge of Dae and in the middle of such lines, cloud pattern, dangcho (a grass) pattern, chrysanthemum pattern or other various types of flowery patterns were designed. Remaining portion of the waist Dae was hanged up on the back, which was initially expressed as directed from the left to the right but thereafter expressed. without orderly fashion,. to the direction of the left from the right and vice versa, Dae was in the shape of Yaja Dae. In this regard, an issue of when or where such a disorderly fashion of the direction of the remaining portion of waist Dae was originated is also presented to be clarified. In case of the Ryuneung, Hong-neung and You-neung which have civil servants' stone images wearing exceptional costume (Jo-bok), waist Dae of the Ryu-neung and Hong-neung are designed in the mixture of dual cranes pattern, cosecutive beaded pattern and chrvsenthemum pattern and that of You-neung is designed in cloud pattern. (4) Hol. Although materials of the Hol held in hand of civil servants' stone images are not identifiable, those should be the ivory Hol as all the Baek Gwan's erected as stone images should be high class officials. In the styles, no significant changes were found, however the Hol's expressed on civil servants' stone images of the Yi-dynasty were shaped in round top and angled bottom or round top and bottom. Parcicularly, at the age of the King Young-jo the Hol was expressed in the peculiar type with four angles all cut off. (5) Hwa (shoes). As the shoes expressed on civil servants' stone images are covered with the lower edges of the Po, the styles thereof are not exactly identifiable. However, reading the statement "black leather shoes for the first class (1 Poom) to ninth class (9 Poom)," recorded in the Gyeongkook Daejon, we can believe that the shoes were worn. As the age went on, the front tips of the shoes were soared and particularly, at the Hong-neung of the King Go-jong the shoes were obviously expressed with modern sense as the country were civilized.