• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
• /
• v.25 no.1
• /
• pp.57-81
• /
• 1997

Numerical prediction of nocturnal thermal high in summer of the 1995 near Taegu city located in a basin has been carried out by a non-hydrostatic numerical model over complex terrain through one-way double nesting technique in the Z following coordinate system. Under the prevailing westerly winds, vertical turbulent fluxes of momentum and heat over mountains for daytime hours are quite strong with a large magnitude of more than $120W/\textrm{m}^2$, but a small one of $5W/\textrm{m}^2$ at the surface of the basin. Convective boundary layer (CBL) is developed with a thickness of about 600m over the ground in the lee side of Mt. Hyungje, and extends to the edge of inland at the interface of land sea in the east. Sensible heat flux near the surface of the top of the mountain is $50W/\textrm{m}^2$, but its flux in the basin is almost zero. Convergence of sensible heat flux occurs from the ground surface toward the atmosphere in the lower layer, causing the layer over the mountain to be warmed up, but no convergance of the flux over the basin results from the significant mixing of air within the CBL. As horizontal transport of sensible heat flux from the top of the mountain toward over the basin results in the continuous accumulation of heat with time, enhancing air temperature at the surface of the basin, especially Taegu city to be higher than $39.3^{\circ}C$. Since latent heat fluxes are $270W/\textrm{m}^2$ near the top of the mountain and $300W/\textrm{m}^2$ along the slope of the mountain and the basin, evaporation of water vapor from the surface of the basin is much higher than one from the mountain and then, horizontal transport of latent heat flux is from the basin toward the mountain, showing relative humidity of 65 to 75% over the mountain to be much greater than 50% to 55% in the basin. At night, sensible heat fluxes have negative values of $-120W/\textrm{m}^2$ along the slope near the top of the mountain and $-50W/\textrm{m}^2$ at the surface of the basin, which indicate gain of heat from the lower atmosphere. Nighttime radiative cooling produces a shallow nocturnal surface inversion layer with a thickness of about 100m, which is much lower than common surface inversion layer, and lifts extremely heated air masses for daytime hours, namely, a warm pool of $34^{\circ}C$ to be isolated over the ground surface in the basin. As heat transfer from the warm pool in the lower atmosphere toward the ground of the basin occurs, the air near the surface of the basin does not much cool down, resulting in the persistence of high temperature at night, called nocturnal thermal high or tropical night. High relative humidity of 75% is found at the surface of the basin under the moderate wind, while slightly low relative humidity of 60% is along the eastern slope of the high mountain, due to adiabatic heating by the srong downslope wind. Air temperature near the surface of the basin with high moisture in the evening does not get lower than that during the day and the high temperature produces nocturnal warming situation.

• Knowledge Management Research
• /
• v.23 no.1
• /
• pp.203-225
• /
• 2022

Competition in the OTT (Over the Top) service market is getting fiercer since global OTT services enter the domestic market and existing platforms are actively reorganized. As powerful competitors with ultra-luxurious content continue to enter the marke with diversity required by users, various efforts are required for OTT service platforms to prevent subscriber churn in order to generate continuous revenue. Thus, this study tried to examine the effect of OTT service characteristics on continuous use intention through an empirical analysis based on Expectation-Confirmation Model(ECM). A total of 386 responses were collected from individuals who have experience or are currently using OTT service and analyzed using AMOS 24. Results show that content curation, content richness, and audience activity had a significant effect on expectation confirmation. Also, expectation confirmation had a significant effect on perceived usefulness and user satisfaction while perceived usefulness had a significant effect on user satisfaction, significantly influencing continuous intention to use OTT. Finally, price fairness was found to strengthen all proposed relationships. The findings are expected to provide useful information for service and content development for subscriber retention, which has the most direct impact on revenue generation of OTT service providers.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.7 no.1
• /
• pp.103-115
• /
• 1969

A study has been made on the time of nitrogen top-dressing and the method of top-dressing to establish the higher yielding cultural method for wheat at Suwon. In this experiment, it was observed that the application of nitrogen top-dressing with urea leaf spray as spike fertilizer increased the yield by 4~6 percent over nitrogen top-dressing of equal quantity only. Considering the yield and various factors concerned, it is reasonable to apply top-dressing on mid and late of March in Suwon area.

• Journal of KIISE:Databases
• /
• v.36 no.3
• /
• pp.189-197
• /
• 2009

Top-k queries are important to many wireless sensor applications. Conventional Top-k query processing algorithms install a filter at each sensor node and suppress unnecessary sensor updates. However, they have some drawbacks that the sensor nodes consume energy extremely to probe sensor reading or update filters. Especially, it becomes worse, when the variation ratio of top-k result is higher. In this paper, we propose a novel Top-k query processing algorithm for energy-efficiency. First, each sensor determines its priority as the order of data gathering. Next, sensor nodes that have higher priority transmit their sensor readings to the base station until gathering k sensor readings. In order to show the superiority of our query processing algorithm, we simulate the performance with the existing query processing algorithms. As a result, our experimental results show that the network lifetime of our method is prolonged largely over the existing method.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.2
• /
• pp.50.3-50.3
• /
• 2019

We show that dynamical evolution in a strong (Galactic Centre-like) tidal field can create clusters that would appear to have very top-heavy IMFs. The tidal disruption of single star forming events can leave several bound 'clusters' spread along 20~pc of the orbit within 1-2 Myr. These surviving (sub)clusters tend to contain an over-abundance of massive stars, with low-mass stars tending to be spread along the whole 'tidal arm'. Therefore observing a cluster in a strong tidal field with a top-heavy IMF does not mean the stars formed with a top-heavy IMF.

• Korean Journal of Computational Design and Engineering
• /
• v.7 no.1
• /
• pp.42-56
• /
• 2002

Presented in this study is a top-down functional requirement analysis procedure and the desired functionalities for PDM system development, and the benefits of top-down approach over a conventional bottom-up approach is also shown. For the purpose of top-down requirement analysis for PDM system, this study proposes 4P modeling view. 4P modeling view is defined as a modeling perspective for classifying functional requirements and integrating product-related information objects that must be man-aged within PDM systems. Based on 4P modeling templates, benchmarking analysis of commercially major PDM products is conducted and as a result of this analysis, this study suggests desired functionalities for PDM system.

• Journal of the Korean Society of Costume
• /
• v.34
• /
• pp.169-182
• /
• 1997

Focusing on khotan located in the southern Silk Route which was one of the most important kingdoms in the Tarim Basin this study attempts to examine the changes of costume in Khotan by compar-ing the costumes in the painted panel showing the story of silk princess with the excavated costumes from ancient tombs. Furthermore this study attempts to inves-tigate the impacts of cultural exchange be-tween China and its western neighboring country Eastern and Western Turkestan on costume. Excavated costumes from the Shanpula ancient tomb in the region of Khotan and from ancient Niya in the esat-ern border of Khotan and discoveries from Rawak and Dandan-oilik near by Yotkan the ancient capital of Khotan are exam-ined. Basic Khotan's costume was the two piece style of tops and trousers. Over the basic costume wearing a top wear with half sleeves was popular. Skirt was worn by women. Even though there were many kinds tops were classified into the two types kaftan and tunic. Thouth Khotan maintained a association with China for a long time the style of Khotan costume had imbued to China. Top wear with half sleeves was worn frequently in Khotan. Also in China top wear with half sleeves was worn as over-wear which was called ban-xiu ban-bi bei-zi Costume style of China is covering the body profoundly and wrapping front edge toward the right. The types of chi-nese top wear with half sleeves for exam-ple round-neck·confronting front edge crossing-neck·confronting front edge tu-nic type discord with the traditional chi-nese costume style There were many cas-es that half sleeved top wear was worn as over wear in T'ang dynasty. The phenom-enon was due to the prevalence of 'ho' (foreign) and half sleeved top wear was introduced by the countries to the west of China Khotan. A round neck garment was a general type for the men of cuntries to the westof China. Also Chinese wore round neck garment since South and North Dynasty The type of Chinese round neck garment was not tunic but kaftan. From costume relics and ancient paintings the type of Khotan's round neck garment was tunic which was recorded on the Chinese histori-cal documents as " guan-tou-shan" that is tunic the type of persian costume, Even thgough the painted panel showing the sto-ry of silk princess was made in the it me when Turks was a dominion on Central Asia Khotan's costume style was not changed toward Turk's costume style and remained tunic style.

• Journal of Broadcast Engineering
• /
• v.23 no.4
• /
• pp.549-558
• /
• 2018

We designed and implemented streaming server based on MEPG DASH, which is able to provide high quality video with low-latency live streaming service like 360 VR video on the existing cable network via low-spec media service devices such as IPTV and OTT(Over the Top) SettopBox. We also designed and applied management process which is cable of supporting services by cashing streaming video file(MPD, Segment Files) to reduce the server response delay time. Further more, we confimred that it is also able to provide high quality of tiled video streaming with over 50,000kbps bitrate and 8K@60P through the experiment.

• Transactions of Materials Processing
• /
• v.19 no.8
• /
• pp.494-501
• /
• 2010

The main objective of this study is to examine the sensitivity of calibration curves of FEA of ring compression test to frictional shear factor. Ring compression test has been investigated by measuring dimensional changes at different positions of ring specimen and they include the changes in internal diameter at the middle and top section of the specimen, outer diameter at the middle and top section, surface expansion at the top surface, respectively. Initial ring geometries employed in analysis maintain a fixed ratio of 6 : 3 : 2, i.e. outer diameter : inner diameter : thickness of the ring specimen, which is generally known as 'standard' specimen. A rigid plastic material for different work-hardening characteristics has been modeled for simulations using rigid-plastic finite element code. Analyses have been performed within a definite range of friction as well as over whole range of friction to show different sensitivities to the interfacial friction for different ranges of friction. The results of investigation in this study have been summarized in terms of a dimensionless gradient. It has been known from the results that the dimensional changes at different positions of ring specimen show different linearity and sensitivity to the frictional condition on the contact surface.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.43 no.4
• /
• pp.269-272
• /
• 1998

Characteristics of seed and plant growth of the nine local collections of the medicinal plant, Agastache rugosa were evaluated. Seed size of the collection from Garyungsan was larger than the others. Seeds of Damyang collection were the smallest in size. Seeds of the collections were mostly oval shaped. There were no differences between brown and black seed coat color groups in seed width, ratio of seed length to seed width and 1,000 seed weight. Stem lengths of Garyungsan and Bongpyung collections were 99.9 and 95.6 cm, respectively, and were longer than Damyang and Jindo collections. Garyungsan collection had long leaf shape. Leaf size was the smallest for Damyang collection, but was the largest for Bongpyung collection. Inflorescence length of Mokpo collection (15.6 cm) was longer than the average over all collections (12.3 cm). Damyang collection was the shortest (10.1 cm) in inflorescence. Top dry weight of each collection from Soonchun, Bongpyung, Mokpo, Jindo, and Gurye was greater than the average over all collections (20.38 g/plant). Jinju and Damyang collections had less top dry matter than others. There was no difference in the growth traits examined between brown and black seed coat groups. The brown seed group was greater in leaf weight than the black seed group. However, these two groups were not different in stem and inflorescence weight. Collections of A. rugosa from Bongpyung, Soonchun, and Mokpo were promising for commercial cultivation because of their great top dry weight, especially in leaf and inflorescence.