• Journal of the Korea Convergence Society
• /
• v.11 no.3
• /
• pp.53-59
• /
• 2020

Initial response is important in marine oil spills, such as the Hebei Spirit oil spill, but it is very difficult to predict the movement of oil out of the ocean, where there are many variables. In order to solve this problem, the forecasting of oil spill has been carried out by expanding the particle prediction, which is an existing study that studies the movement of floats on the sea using the data of the float. In the ocean data format HDF5, the current and wind velocity data at a specific location were extracted using bilinear interpolation, and then the movement of numerous points was predicted by particles and the results were visualized using polygons and heat maps. In addition, we propose a spill oil particle matching algorithm to compensate for the lack of data and the difference between the spilled oil and movement. The spilled oil particle matching algorithm is an algorithm that tracks the movement of particles by granulating the appearance of surface oil spilled oil. The problem was segmented using principal component analysis and matched using genetic algorithm to the point where the variance of travel distance of effluent oil is minimized. As a result of verifying the effluent oil visualization data, it was confirmed that the particle matching algorithm using principal component analysis and genetic algorithm showed the best performance, and the mean data error was 3.2%.

• Journal of the Korean association of regional geographers
• /
• v.6 no.2
• /
• pp.57-69
• /
• 2000

The purpose of this study is to identify distributional characteristics of autumn droughts in occurrence frequency and to analyze synoptic characteristics on the surface pressure fields and 500hPa levels for autumn droughts in Korea. The regional distributions of autumn droughts in occurrence frequency vary according to the monthly regional distributions of the precipitation variabilities in Korea. In september, the southwestern and the mid western parts of Korean Peninsula have high rate of drought frequency, while the eastern coast regions have low rate of it. It means that the regional distribution of the drought frequency in september indicates west-high and east-low pattern. In October, the regional distribution of the drought frequency shows low variations on regions, but in November the inland areas have low rate of drought frequency, whereas the coastal areas have high rate of it. Negative anomalies appear on the surface and 500hPa level, around Korean Peninsula during the drought period of early autumn. Positive height anomalies areas are extended from the Sea of Okhotsk to the central part of the North Pacific Ocean. It indicates that the occurrence frequencies of blocking high and ridge are high around the Sea of Okhotsk. When the pressure system, such as migratory anticyclone, stays around the Korean Peninsula, a drought occurs. In late autumn drought, the positive anomalies appear in the west and the negative anomalies in the east are generated, respectively and therefore, zonal wind is strong around Korean Peninsula. In consequence, occurrences of droughts in early autumn have a different mechanism from those of late autumn.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.7
• /
• pp.15-25
• /
• 2003

An experimental. study is carried out to investigate the near-wake characteristics of an airfoil oscillating in pitch. An NACA 4412 airfoil is sinusoidally pitched about the quarter chord point between the angle of attack -6$^{\circ}$ and +6$^{\circ}$. A hot-wire anemometer is used to measure the phase-averaged mean velocities in the near-wake region of an oscillating airfoil. The freestream velocities of present work are 3.4, 12.4, 26.2 m/s, and the corresponding Reynolds numbers are 5.3${\times}10^4$, 1.9${\times}10^5$, 4.l${\times}10^5$, and the reduced frequency is 0.1. Streamwise velocity profiles are presented to show the Reynolds number effects on the near-wake region behind an airfoil oscillating in pitch. All the cases in these measurements show that the velocity defects by the change of the Reynolds number are very large at the lowest Reynolds number $R_N$=5.3${\times}10^4$: and are small at the other Reynolds numbers ($R_N$=1.9${\times}10^5$ and 4.l${\times}10^5$) in the near-wake region. A significant difference of phase-averaged mean velocity between 5.3${\times}10^4$, and 1.9${\times}10^5$ is observed. The present study shows that a critical value of Reynolds number in the near-wake of an oscillating airfoil exists in the range between 5.3${\times}10^4$, and 1.9${\times}10^5$.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.73-73
• /
• 2019

지구 표면의 약 2%에 해당하는 담수에서 육상계 전체가 흡수하는 탄소의 50%가 배출되며, 이는 토양표면에서 배출되는 탄소량에 비해 더 큰 수치로 전 지구적 탄소순환 해석에 중요한 역할을 한다. 특히, 내륙수역과 대기의 경계면에서 $CO_2$ 이동은 전 지구적 탄소순환의 중요한 구성요소로 평가되고 있다. 호수와 저수지 같은 담수 저류시설은 육상에서 기인한 탄소의 운송 및 처리 역할을 한다. 하지만, 저수지에서 온실가스배출량을 평가할 수 있는 명확한 방법론이 부족하며, 전지구 규모 GHGs배출량에 대한 추정에 대한 불확실성이 상당히 큰 상황이다. 본 연구에서는 몬순기후대에 위치한 인공저수지를 대상으로 보다 신뢰도있는 온실가스 배출량 추정을 위해 $CO_2$ NAF 산정하고, 산정에 영향을 미치는 인자들을 분석 하였다. 분석을 위해 $CO_2$ NAF 산정에 필요한 수리 및 수질 인자들을 2017년부터 2018년까지 수집하고, 기초통계량 및 상관분석을 실시하였다. 또한, 주성분분석(PCA) 및 다중선형회귀모델(MLR)과 랜덤포레스트(RF) 기법을 사용해 변수 중요도를 평가하였으며, $CO_2$ NAF 산정 주요인자인 기체교환 계수를 경험적 모델 3종(Cole and Caraco, Crusius, Vachon), 표면갱신형 모델 4종(Heiskanen, Maclntyre, Read, Soloviev)을 비교, 검토하였다. 조사기간 동안 기체교환계수 산정 결과 Crusius 모델 예측값이 평균 $0.342(0.047{\sim}4.323)cm\;hr^{-1}$으로 검토한 모델중 가장 낮은 평균값을 보였으며, Heiskane 모델이 $2.135(0.337{\sim}5.152)cm\;hr^{-1}$으로 가장 큰 평균값을 보였다. 대상 수체는 연주기로 완전혼합되며 수온성층이 약화되는 시기에 저수지 표층 아래에 축적된 탄소가 표층으로 전달되어 높은 수준의 p$CO_2$를 보이며, 수표면에 큰 난류 강도가 작용하는 기간에 대기중으로 배출(pulse emission) 기작이 나타난다. NAF 산정결과 경험적 모델의 NAF값($-1246.0{\sim}6510.3mg-CO_2m^{-2}day^{-1}$)은 표면갱신형 모델 NAF값($-1436.1{\sim}8485.7mg-CO_2m^{-2}day^{-1}$)보다 낮은 수준을 보였으며, 풍속의 함수만을 이용하는 경험적 모델보다 부력 플럭스와 난류 혼합의 영향을 고려하는 Macintyre, Heiskanen모델이 성층 저수지의 $CO_2$ NAF 산정에 적합한 것으로 나타났다. $CO_2$ NAF 산정의 주요인자로 MLR모델은 Tw, EC, pH, Chla, TOC, Alk, RF모델은 EC, DO, TOC가 중요 변수로 평가되었다. PCA 분석결과, 수온이 낮고 성층이 약화되며 pH가 낮은 상태에서 NAF가 큰 것으로 나타났다.

• Korean Journal of Remote Sensing
• /
• v.35 no.5_2
• /
• pp.831-840
• /
• 2019

Recently, the span length of long-span bridges is getting longer. As a result, it has been suggested that a new concept called 'super long-span bridge'. In case of super long span bridges, the structure is being complicated and the importance of structural stability is being emphasized. However, until recently, the most commonly used sensors (dual axis clinometer, anemometer, strain gauge, etc.) have got limit about the bridge monitoring. Consequently, we researched the application of a Global Navigation Satellite System (GNSS) to improve the limit of the existing sensors. In this study, the dual axis clinometer, the anemometer and the strain gauge together with the GNSS were used to analyze the behavior of a super-long suspension bridge. Also, we propose the detailed method of bridge monitoring using the GNSS. This study consisted of three steps. First step calculated the absolute coordinates of the towers and the longitudinal axis direction of the study bridge using the GNSS. In second step, through the analysis of the long-term behavior in shortly after construction, we calculated the permanent displacement and evaluated the stability of main towers. Third step analyzed the behavior of bridge by the wind direction and was numerically indicated. Consequently, the bridge measurement using the GNSS appeared that the acquired data is able to easy processing according to the analysis purpose. If we will use together the existing measurement sensors with the GNSS on the maintenance of the super long-span bridge, we figure each error of measurement data and improve the monitoring system through calibration. As a result, we acquire the accurate displacement of bridge and figure the behavior of bridge. Consequently, we identified that it is able to construct the effective monitoring system.

• Korean Journal of Remote Sensing
• /
• v.38 no.6_1
• /
• pp.1245-1255
• /
• 2022

Terra Nova Bay polynya (TNBP) is a representative coastal polynya in East Antarctica, which is formed by strong katabatic winds. As the TNBP is one of the major sea ice factory in East Antarctica and has a great impact on regional ocean circulation and surrounding marine ecosystem, it is very important to analyze its area change and development characteristics. In this study, we detected the TNBP from synthetic aperture radar (SAR) and optical images obtained from April 2007 to April 2022 by visually analyzing the stripes caused by the Langmuir circulation effect and the boundary between the polynya and surrounding sea ice. Then, we analyzed the area change and development characteristics of the TNBP. The TNBP occurred frequently but in a small size during the Antarctic winter (April-July) when strong katabatic winds blow, whereas it developed in a large size in March and November when sea ice thickness is thin. The 12-hour mean wind speed before the satellite observations showed a correlation coefficient of 0.577 with the TNBP area. This represents that wind has a significant effect on the formation of TNBP, and that other environmental factors might also affect its development process. The direction of TNBP expansion was predominantly determined by the wind direction and was partially influenced by the local ocean current. The results of this study suggest that the influences of environmental factors related to wind, sea ice, ocean, and atmosphere should be analyzed in combination to identify the development characteristics of TNBP.

• Journal of the Institute of Convergence Signal Processing
• /
• v.25 no.2
• /
• pp.94-99
• /
• 2024

Recently, wind power has been gaining attention as a highly efficient renewable energy source, leading to various technological developments worldwide. Typically, wind power is operated in the form of large wind farms with many wind turbines installed in areas rich in wind resources. However, in developing countries or regions isolated from the power grid, off-grid small wind power systems are emerging as an efficient solution. To efficiently operate and expand off-grid small-scale power systems, the development of real-time monitoring systems is required. For the efficient operation of small wind power systems, it is essential to develop real-time monitoring systems that can actively respond to excessive wind speeds and various environmental factors, as well as ensure the stable supply of produced power to small areas or facilities through an Energy Storage System (ESS). The implemented system monitors turbine RPM, power generation, brake operation, and more to create an optimal operating environment. The developed small wind power system can be utilized in remote road lighting, marine leisure facilities, mobile communication base stations, and other applications, contributing to the development of the RE100 industry ecosystem.

• Journal of Korea Water Resources Association
• /
• v.54 no.11
• /
• pp.903-913
• /
• 2021

In the flood season, the measurement of the river discharge has many restrictions due to reasons such as budget, manpower, safety, convenience in measurement and so on. In particular, when heavy rain events occur due to typhoons, etc., it is difficult to measure the amount of flood due to the above problems. In order to improve this problem, in this study, a method was developed that can measure the river discharge in a flood season simply and safely in a short time with minimal manpower by combining the functions of a drone and a surface velocity doppler radar. To overcome the mechanical limitations of drones caused by weather issues such as wind and rainfall derived from the measurement of the river discharge using the conventional drone, we developed a drone with P56 grade dustproof and waterproof performance, stable flight capability at a wind speed of up to 36 km/h, and a payload weight of up to 10 kg. Further, to eliminate vibration which is the most important constraint factor in the measurement with a surface velocity doppler radar, a damper plate was developed as a device that combines a drone and a surface velocity Doppler radar. The velocity meter DSVM (Dron and Surface Veloctity Meter using doppler radar) that combines the flight equipment with the velocity meter was produced. The error of ±3.5% occurred as a result of measuring the river discharge using DSVM at the point of Geumsan-gun (Hwangpunggyo) located at Bonghwang stream (the first tributary stream of the Geum River). In addition, when calculating the mean velocity from the measured surface velocity, the measurement was performed using ADCP simultaneously to improve accuracy, and the mean velocity conversion factor (0.92) was calculated by comparing the mean velocity. In this study, the discharge measured by combining a drone and a surface velocity meter was compared with the discharge measured using ADCP and floats, so that the application and utility of DSVM was confirmed.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.28 no.2
• /
• pp.23-36
• /
• 2010

The purpose of this study is to infer the aspects and significance of Musa basjoo of latter part of Chosun Dynasty by analyzing the planting tendency and planting location of Musa basjoos drawn in total 77 old paintings and the characteristics of the paintings where Musa basjoos appeared, while trying to understand symbolic meanings of floral languages as well as the images and significance of Musa basjoos which appeared in the prose and poetry of Chosun Dynasty, and the results are as follows; With its floral languages of 'waiting', 'parting' and 'beauty', Musa basjoo represented the wealth and resuscitation and it aroused the elegance of hermits in its Taoistic sense. And it also represented 'the unworldliness to get out of transient human affairs' in its Buddhistic sense. Musa basjoos which appeared in 'Garden Custom Painting(庭園雅集圖)', 'Gosa Figure Painting(故事人物圖)' and 'Gyehoe Painting(契會圖)' is considered a device to increase the unworldly atmosphere of gardens and to dignify the elegant meetings of scholars, reflected by the high appearance frequencies of cranes and deer. And it seems that the meaning of Musa basjoo in certain paintings like 'Life-time Paintings(平生圖)', 'Castle City Painting(盛市圖), and 'Cultivating and Weaving Painting(耕織圖)' is an aspiration for wealth and prosperity, and the Musa basjoos planted in temples are considered to have symbolic meanings of aspiration for 'Salvation through Belief' as well as a unworldly meaning which reminds the transiency of human affairs. In addition, the expected effect of experiencing 'the sound of rain falling on the leaves of Musa basjoo' has been pursued, which can be confirmed by the fact that Firmiana simlex with wide leaves similar to Musa basjoo can be frequently spotted near the houses. Meanwhile, Musa basjoos seem to have been planted mainly in front garden or side garden around detached house and Musa basjoos inside the houses seem to have been planted mainly in right side when viewed from the entrance, in relation with the location of bedrooms where it is easier to hear the sounds from the right side of the environment. And the paintings where Musa basjoos appear with strange rocks and bizarre stones among other things have greater part of all the paintings, which is considered a kind of intentional landscaping and a product of mixed materials for elegant appreciation. And the major characters of the painting were involved in the activities of scholars such as arts, and the activities of minor characters were greatly related to their everyday lives. Musa basjoo of Chosun Dynasty in $17^{th}$ and $18^{th}$ century was one of the symbols necessary for description of gardens. And it provided the images of rainy scenes together with scholar culture which had a meaning of self-discipline, and it is assumed that the planting of Musa basjoo with the spirit of cease lessen deavor of a new leaf pushing up the tree and the spirit of resuscitation had the same trace of wheels in the city space of our country as the decline of scholar culture of Chosun Dynasty.

• Korean Journal of Heritage: History & Science
• /
• v.43 no.3
• /
• pp.334-365
• /
• 2010

Mother-of-Pearl craftwork sketch involves the whole process of making a piece of work. Therefore, it includes types, forms, sizes, and patterns of the work. Some information about when and by whom those works were manufactured and who ordered them are still found in some sketches. This paper seeks to find out popular types and patterns of the works in each period and its demand and the way of supply by examining the collection of approximately 1700 Mother-of-Pearl craftwork sketches from the period of Japanese colonization up to the present time, which are owned by Mr. Song Bang-wung, Important Intangible Cultural Heritage no.10. Typical patterns of sketches are the hua-jo(花鳥 : Flowers and Birds), the Sakunja(四君子 : Four Gracious Plants), cultural treasures, figures in folk tales, 'Su-bok(壽福)' characters, and landscape. The pattern sketches have changed according to the circumstances of Korean society. During the period of Japanese colonization from the 1920s to the 1940s the manufacture and the supply and demand of Mother-of-Pearl craftworks were controled by the Japanese government. As a result, many of the patterns were adjusted to the Japanese taste. Most of its customers were also Japanese. During the 1950s after Independence the American Military Forces appeared as new customers due to the Korean War. Thus, the traditional Korean patterns to decorate accessories adored by American soldiers gained popularity. Foreign Mother-of-Perls were imported from the late 1960s to the 1970s. They were bigger and more colorful than those of Korean and it enabled the sketches bigger and the patterns more various. The most popular pattern in this period was the pattern of cultural treasures, such as an image of Buddha, metalcraft works, porcelains and pagodas. In terms of a technique, new techniques, such as engraving and rusting were introduced. There was a great demand for Mother-of-Pearl craftworks in the 1970s as people were highly interested in them. They were entirely made to order and there was a large demand from diverse organizations, furniture dealers and individuals. And the Mother-of-Pearl craftwork was in full flourish in the 1970s due to the country's economic development and the growth of national income. Mass production of the works was possible and the professional designers who drew patterns actively worked in this period. The favor of Mother-of-Pearl craftworks declined in the 1980s since the built-in furniture and the Western style of furniture became prevalent due to the change of housing into apartments. But it seemed that the manufacture of Mother-of-Pearl craftworks revived for once the technique of Kunum-jil(끊음질 : cutting and attaching) became popular in Tong-young(統營). After the 1990s, however, the making of Mother-of-Pearl craftworks gradually declined as the need of them decreased. Now it barely maintains its existence by a few artisans.