• Industry Promotion Research
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• v.7 no.1
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• pp.81-87
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• 2022

This study used a method of comparing and analyzing various editions of Jeokcheonsu, and aims to confirm why different views have arisen on commentaries that differ according to the perspective of one original text, which interpretation is more valid among them. The biggest part of the misunderstanding of Myeongri theory in Jeokcheonsu is Kyeokguk theory. Jeokcheonsu does not set a high value on Kyeokguk, and it is highly regarded as the Myeongri classics that emphasizes Eokbuyongsin. However, as a result of classifying the original text by theory, we can see there are about 5 sentences that directly mention Eokbu theory, but 9 sentences that explain Kyeokguk theory and 15 sentences if we include the sentences that explain Jonggyeok and Hwagyeok. Even looking that metaphoric speech is mainly used, it is also clear that it's not a book written to be read by a beginner of Myeongri. This is Myeongri texts written to convey more profound logic and enlightenment to a person who has sufficient knowledge by having learned the principle of Myeongri. A single sentence of 'Jaegwaninsubunpyeonjeong Gyeomronsiksanggyeokgukjeong' would have been sufficient to explain the Kyeokguk theory, because it's written on the assumption of the reader's level. Among the later commentaries about the theory of Myeongri contained in Jeokcheosu, 4 persons'commentaries on the original text of 'Palkyeok', 'Gwansal', Sangkwan', 'Wolryeong', 'Saengsi', 'Cheongtak' related to Kyeokguk theory was compared and analyzed.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.583-586
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• 2010

최근에 제주의 생명수인 용천수에 대한 관심이 줄어들면서 이에 대한 문화적 가치가 잊혀지고, 보존이 제대로 이루어지지 않고 있다. 본 논문에서는 이러한 상황을 개선하고자 최근 각광받고 있는 위젯(Widget), 트위터(Twitter), 블로그(Blog) 등의 소셜네트워크를 통해 용천수에 대한 흥미롭고 정확한 정보를 전달하여 우리의 문화자원인 용천수를 보존하고 그 가치를 회복하는 방안을 제시하고자 한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.1
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• pp.41-52
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• 1989

Numerical characteristics for the shallow water equation are analyzed with ADI, Hansen, Heaps, Richtmyer and MacCormack schemes. Stability, CPU time and accuracy are investigated for the linear model which has analytic solutions and circulation is simulated for the nonlinear model. The results show that ADI method has some defects in CPU time and accuracy for the computation of velocity. But ADI method simulates circulation well and has the largest stability region. Richtmyer scheme is the best among the other explicit schemes. Effective viscosity term is found to be essential for numerical experiments of the shallow water equation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.3 no.1
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• pp.14-20
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• 1991

Accurate estimation of irregular wave transformation when the waves propagate from deep water to shallow water region is very important for the design of coastal structures and establishing beach erosion control. In this study. the transformation of directional spectrum is tested numerically using a conservation equation for energy flux and. based upon the joint distribution of wave height. period and wave direction. shoaling effects are predicted in the shallow water region. The applicability of the proposed procedure is verified through comparison with field observation data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1237-1246
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• 2015

A novel technique was proposed to calculate fluxes accurately by separation of flow area into a part of step face which is dominated by flow resistance of it and an upper part which is relatively less affected by the step face in analyzing shallow-water flows over discontinuous topography. This technique gives fairly good agreement with exact solutions, 3D simulations, and experimental results. It has been possible to directly analyze shallow-water flows over discontinuous topography by the technique developed in this study. It is expected to apply the developed technique to accurate evaluation of overflows over weirs or retaining walls (riverside roads) and areas flooded by the inundation in the city covered in discontinuous topography.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.309-309
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• 2020

직립 구조물을 지나는 천수 흐름의 해석에서 구조물에 의한 영향이 지배적인 그 전면과 비교적 덜한 그 위의 영역으로 구분하여 흐름률을 계산하는 새로운 기법이 제안되었으며, 그 모의 결과는 정확해, 가상의 문제에 대한 3차원 모의 결과, 그리고 실험 결과와 대체로 만족스런 일치를 보였다(Hwang, 2015; Hwang, 2016). 또한, Hwang (2019)은 측면 위어에 대한 부정류 실험(Kim, 2013)에서 직립의 측면 위어를 통해 수로와 저류지 사이의 흐름이 교환되는 실험 경우에 적용하여 새로운 기법에 의한 수치 모형을 시험한 바 있다. 이 연구에서는 측면 위어에 대한 Kim (2013)의 나머지 실험 경우에 대해서도 Hwang (2015)의 기법을 적용하여 불연속 지형을 이루는 직립 측면 위어의 월류량을 평가하였다.

• Korean Journal of Heritage: History & Science
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• v.47 no.4
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• pp.136-161
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• 2014

This paper investigates the Buddhist sculpture and wall-painting enshrined in the halls of Bunhwangsa (Bunhwang temple) at Gyeongju in the mid-Silla period, which are thoroughly unknown to us except through textual records of Samgukyusa compiled by Priest Ilyeon in the late thirteenth century. According to Samgukyusa, a clay portrait-sculpture of Monk Wonhyo, made by his son Seolchong, was placed in Bunhwangsa. This image faced to the side, because he turned his body toward Seolchong when Seolchong bowed to this image. This story suggests that the portrait image of Wonhyo was most likely made after the Vimalakirti images, which were popular in China from the Six Dynasties period on, especially the Vimalakirti images of the early Tang period, turning his head and body toward Bodhisattva Manjusi seated opposite. The Vimalakirti image of Seokkuram might show the portrait image of Wonhyo. A wall-painting of a Thousand-Armed Avalokiresvara who has a thousand arms with a thousand eyes, called by the name 'Great Mercy with a Thousand Hands', was enshrined on the north wall of the left hall of Bunhwangsa. During King Gyeondeok's reign, Himyeong and her five-year-old blind child prayed before this image, and the blind child gained eyesight. While praying, they sang a song pleading for one of the thousand eyes which the Bodhisattva had in his hands. This song implies that Thousand-Armed Avalokiresvara had a thousand eyes, one painted on each hand. The fact that Thousand-Armed Avalokiresvara of Bunhwangsa was called 'Great Mercy with a Thousand Hands' indicates that this painting was based on the scripture Thousand-Armed Avalokiresvara Sutra translated by Bhagavaddharma in about 655, in the Tang period, which also has 'Great Mercy' in its title. In the year 755, a gilt bronze image of Medicine Buddha was made in Bunhwangsa, using nearly 61 tons of bronze to cast. The huge amount of bronze suggests it includes not only the Buddha statue but many other images such as two attendant Bodhisattvas of Suryaprabha and Candraprabha, Eight Great Bodhisattvas, or Twelve Guardians. Seven images of Medicine Buddha might have been made in accordance with the scriptural text of Seven Medicine Buddha Sutra translated by Monk Yijing. Textual evidence and recent excavation have revealed that seven images of Medicine Buddha and their whole attendant images based on Seven Medicine Buddha Sutra were made in the Nara period from 751 to 762 when Queen Gomyo contructed Sinyakusiji temple for the recovery of her husband Shomu. It is fair to assume that one or seven Medicine Buddhas and a whole group of his (their) attendant images were made for the main hall of Bunhwangsa temple in 755.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.100-100
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• 2022

일반적으로 유체와 구조물간 상호작용의 수리동역학적 모의에서는 벽경계조건을 통하여 유동에 대한 구조물의 영향이 반영된다. 하지만 도심지에서 발생한 홍수를 예측하려는 경우 이러한 방법으로는 밀집한 구조물들 사이에 형성된 좁은 길들로 인하여 세밀한 격자망을 요하여 큰 계산량을 유발하고 빠른 예측 속도를 기대할 수 없게 한다. 최근 이러한 문제를 극복하기 위해 성긴 격자망에서도 구조물의 유체에 대한 영향을 반영할 수 있도록 하는 방법들이 큰 관심을 받고 있다. 그 중에서도 다공성 천수방정식은 벽경계조건 대신 다공도(posority)의 개념을 이용한 모형으로 도시범람모의에 있어 계산량과 정확도를 가장 적절하게 타협한 모형으로 보고되고 있다. 이러한 흐름에 맞추어 본 연구는 다공도 천수방정식을 해석하는 수치 기법을 개발하였고, 여기에 최근 쌍곡선계 방정식의 수치적 연구들에서 소개된 주요 특징들이 반영되도록 설계하였다. 우선, WENO 기법과 Runge-Kutaa 기법을 통하여 공간과 시간에 대한 고차 정확도를 만족시켰다. 이 때, 재구성 변수와 알고리즘를 새롭게 제시하여 정상흐름조건에 대한 플럭스항과 생성·소멸항간 절단오차에 의한 비물리적인 흐름생성을 억제하였다. 또한, 수치모의 중 음수심의 발생으로 인하여 수치모형이 불안정해지는 현상을 막기 위해, 양-보존성 제한자를 구축하였다. 마지막으로 도심지에서 즐비한 인위적인 구조물에 의해 나타나는 지형적인 불연속의 효과를 적절하게 반영할수 있도록 정상파 재구축의 단계를 구축하여 수치 기법에 반영하였다. 이렇게 구성된 수치기법은 리만문제의 해석해에 기반하여 기존의 주요 연구들의 결과와 비교되었고, 그 결과 본 연구의 방법이 정확성, 수렴성, 안전성의 측면에서 가장 우수함을 수치적으로 증명하였다.

• Journal of Korea Water Resources Association
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• v.56 no.12
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• pp.939-953
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• 2023

Shallow water equations (SWE) serve as fundamental equations governing the movement of the water. Traditional numerical approaches for solving these equations generally face various challenges, such as sensitivity to mesh generation, and numerical oscillation, or become more computationally unstable around shock and discontinuities regions. In this study, we present a novel approach that leverages the power of physics-informed neural networks (PINNs) to approximate the solution of the SWE. PINNs integrate physical law directly into the neural network architecture, enabling the accurate approximation of solutions to the SWE. We provide a comprehensive methodology for formulating the SWE within the PINNs framework, encompassing network architecture, training strategy, and data generation techniques. Through the results obtained from experiments, we found that PINNs could be an accurate output solution of SWE when its results were compared with the analytical method. In addition, PINNs also present better performance over the Artificial Neural Network. This study highlights the transformative potential of PINNs in revolutionizing water resources research, offering a new paradigm for accurate and efficient solutions to the SVE.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.105-105
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• 2021

본 연구에서는 2차원 비선형 천수모형과 수심평균된 스칼라 이송모형을 해석하는 수치모형에 대해 기술하였다. 수치모형의 정확성을 보장함과 동시에 안정성을 높이기 위해 유한체적법, 플럭스 재구성 및 minmod 제한자를 사용하였다. 비선형 천수방정식의 이송항과 바닥 경사항은 계산된 수심의 양수 보존과 흐름의 정상 상태를 보장하기 위한 second order well-balanced positivity preserving central-upwind method를 이용하여 수치적으로 이산화되었다. 마찬가지로, 이송-확산 방정식 내 이송항은 동일한 2차 풍상차분법을 통해 수치적으로 풀이하였다. 격자점 경계면에서의 불연속으로 인한 수치진동을 방지하기 위해 이송항의 계산에 포함된 보존항의 차이로 인해 발생하는 스칼라의 수치확산을 최소화하기 위해 무차원의 비소산함수를 도입하였다. 또한, 확산항은 유한차분법을 이용하여 이산화하였다. 제안된 수치모형은 시간미분항의 계산을 위해 오일러 기법을 적용하여 계산된 수심 및 스칼라의 양수 보존여부와 함께 정지된 흐름의 정상 상태의 보존여부를 확인하였다. 제안된 수치모형의 해석 정확성을 평가하기 위해 1, 2차원 공간 내 다양한 흐름 조건에서의 해석해를 이용한 3개의 벤치마크 테스트를 수행하였다. 평균 제곱근 오차(Root Mean Squared Error, RMSE)를 산정하여 수치모형의 성능을 정량적으로 평가하였으며, 비소산함수를 적용함에 따라 스칼라의 수치확산이 감소하게 되었음을 확인하였다. 또한, 세 차례의 벤치마크 테스트 결과는 공통적으로 수치모형에 의해 계산된 결과값이 비소산함수를 고려함에 따라 해석해와 잘 일치함을 확인하였다.