• The Journal of the Acoustical Society of Korea
• /
• v.35 no.6
• /
• pp.452-465
• /
• 2016

In this study, the structure of a concave annular array transducer was optimized to generate high intensity focused ultrasound for medical therapeutic application. The transducer has a phased array structure composed of several concentric channels that have 40 mm as the radius of curvature. We derived theoretical equations to analyze the sound field of the transducer and verified the validity of the equations by comparing the results calculated by the equations with those from finite element analyses. We also checked the possibility of dynamic focusing at around the geometric focal point. Further, the level of a grating lobe occurring at an unwanted position in the transducer sound field was confirmed to be reducible through the relation between the number of channels and the frequency of the transducer. Hence, the structure of the transducer was optimized to place the main lobe within a specific range from the zenith while systematically reducing the level of the maximum sidelobe including the grating lobe. The designed structure showed the performance better than that targeted at all the focal points.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.17-17
• /
• 2016

이중편파 레이더는 수평 수직반사도($Z_H{\cdot}Z_V$), 차등반사도($Z_{DR}$), 교차상관계수(${\rho}_{HV}$), 차등위상차(${\Phi}_{DP}$) 등 다양한 변수 산출을 통하여 대기 수상체 구분, 우적분포에 영향이 적은 강우량 추정, 밝은 띠(BB, Bright Band)의 탐지 등이 가능하게 됨으로써 수문기상 및 재해관리 분야에 활용성이 점점 더 커지고 있다. 본 연구는 RHI, PPI에서 생산된 레이더 변수를 이용하여 BB를 탐지하고 그 특성을 평가하였다. BB는 레이더를 이용하여 상층대기를 관측할 때 수직단면에서 강수입자가 눈에서 비로 변하는 구간에서 과대하게 높은 반사도가 나타나는 층을 말한다. BB에서는 QPE가 과대 추정되기 때문에, BB의 특성 파악은 레이더의 관측전략 수립과 QPE 보정에 필수적이다. 본 연구에서는 RHI에 의한 $Z_H$의 연직단면분석, RHI와 PPI의 고도각 경사거리(slant range) 빔의 ${\rho}_{HV}$, $Z_{DR}$, $Z_H$에 의한 분석을 통하여 BB의 상단부($BB_{TOP}$), 최정점($BB_{PEAK}$) 및 하단부($BB_{BOTTOM}$)의 고도를 상호 비교 평가하였다. 분석 자료는 KICT X-밴드 레이더에 의한 관측한 2015년 10월 21일의 층상운에 의한 강우를 이용하였다. RHI에 의한 $Z_H$의 연직단면 분석결과 $BB_{top}$, $BB_{bottom}$ 및 $BB_{peak}$는 KICT 레이더 고도(MSL : 40m)를 기준으로 각각 3.26Km, 2.3Km($BB_{width}$: 0.96km) 및 2.7Km로 나타났다. 이 같은 결과는 다른 2가지 분석방법에서도 유사하게 나타나고 있으며, 이는 BB분석을 위해 다양한 변수를 통한 신뢰성 있는 BB의 특성을 파악할 수 있는 기반을 제공한다.

• Journal of Korean Philosophical Society
• /
• v.131
• /
• pp.33-48
• /
• 2014

is Plato's last great philosophical work. 'Nocturnal Council' is located in the end of this work. Many scholars interpret 'Nocturnal Council' into opposite directions. According to one interpretation, this Council is a kind of an addition to supplement the philosophical elements. So this is Plato's 'after-thought'. But another interpretation is that 'Nocturnal Council' is a climax in Plato's political thought. Plato didn't abandon the theory of Idea in . In this respect, we find a coherence between and . Finally, a vague position of 'Nocturnal Council' in remains an opposite interpretations each other.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.21 no.4
• /
• pp.315-326
• /
• 2015

Temporal and spatial variations of surface water temperature in Jinju Bay for the period of 2010~2011 were studied using the data from temperature monitoring buoys deployed at 17 stations in the south coast of Korea. Water temperature shows the maximum late in January and the minimum early in August. Seasonal variation of water temperatures at the north part of the bay is smaller than the middle and the south. In summer, the lowest and the highest of maximum water temperature are distributed around Jijok Channel which is located at the south of the bay. The fluctuations of water temperatures at Noryang and Daebang Channel are smaller than others because of vertical mixing caused by passage of strong tidal currents. Wind and strong currents affect on the stratification of the surface water layer near Daebang Channel. High temperatures come in frequently around the north area when eastward constant flows appear at neap tide as blowing westerly in the springtime at Noryang Channel. Spectral analyses of temperature records show significant peaks at 7~20 day periods at Noryang Channel, 7~20 day and semidiurnal at the west coast of Changsun Island and Jijok Channel and 7~20 day and diurnal at the middle of the bay. Temperature fluctuation at Noryang Channel shows high coherence and has leading phase with those at other stations in the bay. However, the phase of temperature fluctuation at Noryang Channel falls behind that at Daebang Channel. Daebang Channel has an influence on the temperature fluctuation only at the west and middle part of the bay. Cross-correlation analyses for the temperature fluctuation show that Jinju Bay could be classified into six areas; Noryang Channel, the area of convergence and divergence at the north, Daebang Channel, the west coast of Changsun Island, the mixing area at the middle of the bay and the south inside of the bay, respectively.

• Journal of KIISE:Computer Systems and Theory
• /
• v.32 no.1
• /
• pp.39-48
• /
• 2005

According to traditional 2D animation techniques, anticipation makes an animation much convincing and expressive. We present an automatic method for inserting anticipation effects to an existing facial animation. Our approach assumes that an anticipatory facial expression can be found within an existing facial animation if it is long enough. Vertices of the face model are classified into a set of components using principal components analysis directly from a given hey-framed and/or motion -captured facial animation data. The vortices in a single component will have similar directions of motion in the animation. For each component, the animation is examined to find an anticipation effect for the given facial expression. One of those anticipation effects is selected as the best anticipation effect, which preserves the topology of the face model. The best anticipation effect is automatically blended with the original facial animation while preserving the continuity and the entire duration of the animation. We show experimental results for given motion-captured and key-framed facial animations. This paper deals with a part of broad subject an application of the principles of traditional 2D animation techniques to 3D animation. We show how to incorporate anticipation into 3D facial animation. Animators can produce 3D facial animation with anticipation simply by selecting the facial expression in the animation.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.23 no.5
• /
• pp.383-392
• /
• 2011

The basic research of the estuarine circulation at Gyeong-Gi bay has not been well studied up to now, although coastal development pressures have been continuously increased. To understand the oceanographic phenomena at the Han River estuary, it's essential to understand the propagation characteristic of tidal wave which is the strongest external forcing in this region. In this study, we investigate the tidal wave propagation characteristics along the 3 major channels using observation data and numerical model. It is found that 3 channels are all hyper-synchronous and the most important physical factor controlling the tidal wave propagation is topographical convergence of estuary shape and friction. The result of analytic solution at ideal channel considering the topographical convergence and friction show that the contribution of physical role of convergence and friction varies at 3 different channel. And the ratio of convergence and friction at Yeomha channel is four times larger than Seokmo channel. Because of this effect, the location of maximum amplitude at Yeomha channel is showed up downward than Seokmo channel. The ratio of decreasing amplitude and increasing phase per unit distance between stations is bigger than Seokmo channel. Although 3 major channel show a hyper-synchronous pattern, Yeomha shows more frictionally dominant channel and Seokmo channel is more dominantly affected by convergence effect.

• Korean journal of communication and information
• /
• v.22
• /
• pp.77-106
• /
• 2003

As globalization of communication is going on and as the media have become increasingly central to the world economy, media policy matters have become the province of world economic organizations like the IMF and the WTO. The WTO service negotiation is focused primarily on the discriminatory and quantitative barriers associated with the trade of audiovisual services. Domestic measures such as subsidization, content regulation including quotas, and licensing requirements and restrictions on foreign ownership and control are at issues here. These measures have been successfully implemented by countries wishing to withstand competition from the American audiovisual industry. The debate about trade in audiovisual services is permeated by the unstated assumption that these programs are pure commodities whose production, distribution, exhibition and in turn, values are solely determined by the market forces. It is therefore presumed that liberalization of trade in audiovisual services will benefit all, serving cultural pluralism and diversity as well as economic efficiency. However, this assumption is not shared by developing countries, the recipients of U.S. television material. They argue audiovisual sector requires a social and cultural approach, since it plays a key role in the preservation of people's identity and social bonds. They claim that it is the each state's right to define its media policy and to implement it through the means it considers fit. These clashing views over the nature of the audiovisual material and the ways in which protect cultural pluralism and diversity do not confine to be the realm of theoretical debate. Each state's interest and motivation to protect its local industry and to have a competitive advantage in the international market is working in this battle. Consolidation with the countries like Australia, Canada, and EU nations, in favour of cultural exemption, seems to be the best policy for us. However, we are not entirely free from the WTO pressures, considering relation to the U. S. This study analyzes Korean Broadcasting Law compared with those of other OECD countries and tries to propose some strategical guidelines facing WTO service negotiation in the area of broadcasting.

• The Korean Journal of Archival Studies
• /
• no.66
• /
• pp.203-227
• /
• 2020

This article explores the influence of the king in the Joseon dynasty's document transmission system, focusing on some exceptional cases. According to the Joseon's law, the form of official documents depended on rank differences between receiver and sender. However, there were cases of not following the general principles such as Byungjo(兵曹), Seungjeongwon(承政院) and Kyujanggak(奎章閣). Byungjo was a ministry in charge of military administration. Seungjeongwon was a royal secretary institution which assisted the king and delivered king's orders that existed from the early Joseon. Kyujanggak was a royal library and an assistant institution of the king that was established in the JeongJo(正祖) era. Byungjo was regarded as a relatively high-ranking institution when it sent and received military-related documents. Seungjeongwon and Kyujanggak could use Kwanmoon(關文) to upper rank institution. Kwanmoon was the document form used for institutions of the same or lower rank than itself. Conversely, higher rank institutions used Cheobjeong(牒呈) which was stipulated as a document form to using upper rank institution in law to send them. The reason that they could have privileges in transmission document system was that Joseon had an administrative system centered on the king. Byungjo was an institution entrusted with military power from King. Seungjeonwon and Kyujanggak took charge of the assistance and the delivery of King's order. so they could have a different system of receiving and sending document than the others. In conclusion, the Joseon Dynasty operated exceptions in document administration based on the existence of the king, it means Joseon's transmission document system was basically operated under the Confucian bureaucracy with the king as its peak.