FINITE DIFFERENCE METHOD FOR THE TWO-DIMENSIONAL BLACK–SCHOLES EQUATION WITH A HYBRID BOUNDARY CONDITION

YOUNGJIN HEO,HYUNSOO HAN,HANBYEOL JANG,YONGHO CHOI,김준석 한국산업응용수학회 2019 Journal of the Korean Society for Industrial and A Vol.23 No.1

In this paper, we develop an accurate explicit finite difference method for the two-dimensional Black–Scholes equation with a hybrid boundary condition. In general, the correlation term in multi-asset options is problematic in numerical treatments partially due to cross derivatives and numerical boundary conditions at the far field domain corners. In the proposed hybrid boundary condition, we use a linear boundary condition at the boundaries where at least one asset is zero. After updating the numerical solution by one time step, we reduce the computational domain so that we do not need boundary conditions. To demonstrate the accuracy and efficiency of the proposed algorithm, we calculate option prices and their Greeks for the two-asset European call and cash-or-nothing options. Computational results show that the proposed method is accurate and is very useful for nonlinear boundary conditions.

농업기반시설물 지진피해 조사를 통한 취약부 분석

허준 ( Joon Heo ),허지선 ( Jisun Heo ),양영진 ( Youngjin Yang ),이승훈 ( Seunghoon Lee ),봉태호 ( Taeho Bong ) 한국농공학회 2018 한국농공학회 학술대회초록집 Vol.2018 No.-

지진은 그 자체로서의 피해뿐만 아니라, 2011년 동일본대지진에서와 같이 국가 기반산업시설을 붕괴시킬 수 있는 막대한 추가피해를 유발할 수 있다. 직접적 인명, 재산상 피해와 더불어 국민 삶의 질을 결정하는 기본적인 발전시설, 라이프라인, 통신시설 등과 같은 경제, 산업의 기반을 근본적으로 교란시킬 수 있다. 또한, 농업기반시설물의 피해를 발생 시킬 수 있으므로 지진에 의한 농업기반시설물의 취약부를 평가하고 적합한 내진보강방안을 검토하는 것은 중요하다. 2017년 포항지진에 의해서도 농업기반시설물 저수지 제체에 피해가 발생하였다. 지진 발생후 농업기반시설물 성토구조물의 변형 형태, 위험경감에 대한 연구는 미비한 실정이다. 본 연구에서는 포항지진에서 발생한 농업기반시설물의 피해와 동일본대지진에서 발생한 농업기반시설물의 피해를 조사 분석하여, 지진 발생시 농업기반시설물 성토구조물의 취약부를 평가하였다. 지진에 의한 농업용 저수지 제체의 주요 변형형태, 변형위치 및 피해규모 등을 고찰하였다. 본 연구를 통해 농업용 저수지 제체의 내진보강을 위한 주요 위치 및 방법 등에 활용될 수 있다고 판단된다.

Feasibility study of block-matching and 3D filtering denoising algorithm in multi-material decomposition technique for dual-energy computed tomography

Heo Seo-Yeong,An Byungheon,Kim Dohyeon,Park Minji,Lee Haenghwa,Lee Youngjin 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.3

AS a medical imaging technology, dual-energy computed tomography (DECT) has attracted attention owing to its higher accuracy in terms of material separation compared with conventional single-energy CT imaging. A multi-material decomposition (MMD) technique that can separate two or more materials from DECT images has recently been developed. Although a highly accurate material separation can be obtained when MMD technology is applied to CT images, the inevitable addition of noise to the image is a disadvantage. Thus, block-matching and 3D fltering (BM3D) denoising algorithm was modeled to evaluate its applicability to CT images of materials separated using MMD technology. The simulation results confrmed that when the BM3D denoising algorithm was applied to CT images separated from the material using MMD technology, the root mean square (RMS), structural similarity index, and coefcient of variation (COV) were improved by 92.44%, 16.44%, and 92.82%, respectively, compared to when only MMD was applied. In addition, the experimental results showed the same tendencies as the simulations, and volume fraction accuracy (VFA) along with the RMS and COV evaluation parameters showed the best results when BM3D was applied to CT images. Improved results were obtained using the BM3D denoising algorithm when applying the MMD technique to DECT images.

pH-Dependent Aqueous Solution-Grown Highly Nanocrystalline Nickel Cobalt Sulfides (NiCo2S4)

Jeon Youngjin,Choi Kwanbeom,Lee Seungje,Heo Jungseok 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.6

NiCo2S4 is an important bimetallic spinel-type sulfide that is typically synthesized using a two-step method, which commonly involves water as a reaction medium. Here, we show that highly crystalline and high surface area NiCo2S4 could be synthesized into a nanoflake-entangled shape. Control of solution pH under a hydrothermal condition affects the compositions and morphologies of products. It reveals that the pKas of two transition metal ions and L-cysteine (L-Cys) play a crucial role in the formation of NiCo2S4. Various spectroscopic analyses were performed to characterize these products, including X-ray diffraction, energy-dispersive X-ray spectroscopy, gas sorption, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy.

Determining the etiology of small bowel obstruction in patients without intraabdominal operative history: a retrospective study

Jang Youngjin,정성민,Heo Tae Gil,Choi Pyong Wha,Kim Jae Il,정성원,Jun Heungman,신용찬,Um Eunhae 대한대장항문학회 2022 Annals of Coloproctolgy Vol.38 No.6

Purpose: Most of the causes of small bowel obstruction (SBO) in patients without a history of abdominal surgery are unclear at initial assessment. This study was conducted to identify the etiology and clinical characteristics of SBO in virgin abdomens and discuss the proper management. Methods: A retrospective review involving operative cases of SBO from a single institute, which had no history of abdominal surgery, was conducted between January 2010 and December 2020. Clinical information, including radiological, operative, and pathologic findings, was investigated to determine the etiology of SBO. Results: A total of 55 patients were included in this study, with a median age of 57 years and male sex (63.6%) constituting the majority. The most frequently reported symptoms were abdominal pain and nausea or vomiting. Neoplasm as an underlying cause accounted for 34.5% of the cases, of which 25.5% were malignant cases. In patients aged ≥60 years (n=23), small bowel neoplasms were the underlying cause in 12 (52.2%), of whom 9 (39.1%) were malignant cases. Adhesions and Crohn disease were more frequent in patients aged <60 years. Coherence between preoperative computed tomography scans and intraoperative findings was found in 63.6% of the cases. Conclusion: There were various causes of surgical cases of SBO in virgin abdomens. In older patients, hidden malignancy should be considered as a possible cause of SBO in a virgin abdomen. Patients with symptoms of recurrent bowel obstruction who have no history of prior abdominal surgery require thorough medical history and close follow-up.

Fume Filtration Performance Test

Hong Heo(허홍),Youngjin Seo(서영진) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.4

Validity and Reliability of Metacognitive Rating Scale for Nursing Students

( Lee¸ Kyunghee ),( Heo¸ Youngjin ),( Han¸ Mihwa ),( Kim¸ Mijung ),( Choi¸ Hyunseok ) 한국정신간호학회 2021 정신간호학회지 Vol.30 No.3

Purpose: The aim of this study was to determine the reliability and validity of the metacognition rating scale (MCRS), which is a revised version of the existing metacognition questionnaire (MCQ) with anger and anxiety added. Methods: A survey was conducted on 591 nursing students at colleges in North and South Gyeongsang Provinces, South Korea. The collected data were processed for the reliability and validity of the MCRS through Cronbach’s α and confirmatory factor analysis using SPSS 26.0. Results: Cronbach’s α for the reliability of MCRS was calculated at .88, .86, .77, .74, and .66 for five subfactors. Among the five subfactors, the first, second, third, and fifth factors showed high correlation in each of six items. Factor 4 was highly correlated in 5 out of 6 questions. Conclusion: The data confirm that the MCQ revised to include anger and anxiety is both reliable and valid for nursing students. Therefore, this scale can be used to identify the maladaptive metacognition of nursing students in stressful situations.

과팽창 초음속제트의 방향 제어를 위한 유체역학적 제어의 동특성 연구

허준영(Junyoung Heo),유광희(Kwanghee Yoo),조민경,성홍계(Hong-Gye Sung),이열(Yeol Lee),전영진(Youngjin Jeon),조승환(Seunghwan Cho) 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.5

기계적 제어장치를 사용하지 않으면서도 추력방향 제어가 가능한 유체역학적 추력편향제어(Fluidic Thrust Vector Control; FTVC)기법에 대한 연구 논문이다. 2차 유동은 주 유동 흐름과 같은 방향으로 분사하였고, 선행연구를 통해 정상(steady)상태의 수치해석 결과는 실험과 비교·검증하였다. 이를 바탕으로 비정상(unsteady) 수치해석을 수행하였고, 위아래로 제트가 편향이 될 때에 소요되는 시간과 벽면에서의 압력 분포 등을 조사하여 추력벡터의 동특성을 연구하였다. The purpose of this research is to investigate the dynamic characteristics of fluidic thrust vector control using the co-flow injection. In previous research, both numerical and experimental approaches for steady state were conducted to investigate operation-parameters and detail flow structure of the fluidic thrust vector control system. Based upon the previous results, numerical unsteady calculation was conducted to analyze the dynamic characteristics of jet up- and down-ward vectoring so that the transition time and the pressure distribution along the wall, and so on were investigated.

교육공간으로서 메타버스에 관한 고찰

김영진(Kim, Youngjin),허지훈(Heo, Jihoon),최승훈(Choe, Seunghun),백성혜(Paik, Seounghey) 한국교원대학교 융합교육연구소 2022 융합교육연구 Vol.8 No.1

최근 메타버스에 관한 관심이 높아짐에 따라 교육계에서도 새로운 교육공간으로서 메타버스에 관한 논의가 이어지고 있다. 본고에서는 이론적 맥락에서 교육공간으로서 메타버스의 활용 가능성과 내재된 한계를 살펴보고자 하였다. 이에 메타버스를 다룬 기존 연구들을 정리한 후, 장상호의 교육본위론을 바탕으로 교육공간을 정의하여 교육공간으로서 메타버스의 가능성과 한계를 제시하였다. 연구 결과, 메타버스의 교육적 가능성으로서 역동적 교육관계의 가능성, 언어에서 체험으로 교육 소재 확장의 가능성, 관습적 교육관이라는 그릇된 교육관 수정의 가능성이 도출되었다. 한편 메타버스의 교육적 한계로서 교육적 시숙의 어려움, 접근성의 문제, 교육적 효과의 경험적 검증 부재라는 결론을 얻을 수 있었다. As interest in metaverse has increased recently, the education community has been discussing metaverse as a new educational space. In this paper, we examine the possibility and inherent limitations of metaverse as an educational space in theoretical context. After summarizing the existing research on metaverse, the possibility and limitations of metaverse as an educational space are presented by defining the educational space based on Jang Sang-ho s educational-centered theory. Studies have shown that the possibility of dynamic educational relationships, the possibility of expanding educational materials from language to experience, and the possibility of correcting the wrong view of education. On the other hand, the educational limitations of metaverse include the difficulty of educational trial, accessibility, and lack of empirical verification of educational effectiveness.

DRAM에 맵핑되는 코드를 보호하기 위한 고성능 암호화 엔진

허인구(Ingoo Heo),최홍묵(Hongmook Choi),정영진(Youngjin Chung),박재철(Jaechul Park),노미정(Mijung Noh) 대한전자공학회 2018 대한전자공학회 학술대회 Vol.2018 No.11