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최승찬(Seungchan Choi),복다미(Dami Bok),임승호(Seungho Lim),오병영(Byungyung Oho),박준모(Junmo Park),정언재(Eunjae Jung),이한성(Hanseong Lee),도중석(Jungseok Do),왕성준(Seongjun Wang) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
CAE is one of powerful tools to save time and cost because vehicle performance can be reviewed and improved in early development stage. Moreover, it is possible to enhance the drawing completeness of part suppliers at the initial design stage by simple system level CAE analysis items. In this case, vehicle OEM should define the reasonable specification and guide of the system level simulation through comprehensive analysis in entire vehicle system. In this point of view, the steering wheel rim mode vibration problem is a good sample to apply system level analysis. This type of vibration can be issued in acceleration and cruse driving condition at 2000~4000RPM if the stiffness of the steering wheel rim is insufficient. In this paper, the contribution of the rim mode was analyzed in the vehicle model and the appropriate target to control the rim mode vibration with equivalent dynamic stiffness was defined in system level through the investigation with vehicle database. Also, steering wheel design guides were proposed to improve the stiffness and weight using the optimization analysis.
Choi, Moonhee,Cho, Seungchan,Song, Yeonghwan,Park, Sungkyun,Kim, Yangdo Elsevier 2015 CURRENT APPLIED PHYSICS Vol.15 No.4
<P><B>Abstract</B></P> <P>We have successfully developed a Dy-free grain boundary diffusion process with neodymium hydride (NdH<SUB>x</SUB>) alloy to the permanent magnet Nd<SUB>2</SUB>Fe<SUB>14</SUB>B powders using hydrogenation – disproportionation – desorption – recombination (HDDR) method. All the diffusion treatments were performed at 700–800 °C for various annealing time under the high vacuum with rotating diffusion method that effectively control the abnormal grain growth. The coercivities of Dy-treated Nd<SUB>2</SUB>Fe<SUB>14</SUB>B powders were varied from 9.5 kOe to 13.2 kOe but the remanence was decreased to 8.1 kG (10% reduction) depending on dysprosium hydride (DyH<SUB>x</SUB>) content and diffusion treated time. However, the coercivity and remanence of Dy-free diffusion treated powder have been increased to 12.2 kOe (28.5% enhancement) and 11.1 kG (22% enhancement) at the optimal diffusion treatment (800 °C for 3 h), respectively. This unique simultaneous enhancement is to isolate the magnetic coupling between Nd<SUB>2</SUB>Fe<SUB>14</SUB>B grains by creating non-magnetic Nd grain boundaries and enhance the alignment of the Nd<SUB>2</SUB>Fe<SUB>1</SUB>4B hard magnetic phase, fabricated by optimal diffusion conditions.</P>
Cho, Seungchan,Okayasu, Rin,Kikuchi, Keiko,Choi, Moonhee,Park, Jehong,Jo, Ilguk,Lee, Sang-Bok,Kwon, Hansang,Kim, Yangdo,Miyazaki, Takamichi,Kawasaki, Akira Elsevier 2019 Scripta materialia Vol.159 No.-
<P><B>Abstract</B></P> <P>We successfully fabricated a controllable intragranular pore containing hydroxyapatite (HA) by the combination of an electric current assisted sintering and pre-heat treatment process. The microstructure and mechanical properties of the sintered HA bulk with and without intragranular pores were investigated in this study. Fully densified HA fabricated by the combination of an electric assisted sintering and pre-heat treatment process showed extremely superior mechanical properties. Meanwhile, hierarchically structured porous HA consisting of nanosized intragranular pores without macropores in the grain boundary showed dramatically decreased elastic modulus by different fracture mechanism compared with fully densified HA.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
동시성을 포함한 액티비티 다이어그램 기반 테스트 시나리오 생성 기법
백승찬(Seungchan Back),최효린(Hyorin Choi),이병정(Byungjeong Lee),이정원(Jung-Won Lee) 한국정보과학회 2016 정보과학회논문지 Vol.43 No.9
소프트웨어 테스트에 대한 중요도는 오늘날의 산업 전반적으로 커지고 있으며 효과적인 테스트를 지원하기 위한 많은 방법들이 연구되고 있다. 이에 테스트 설계를 위해 시스템의 요구사항을 정형화하는 방법으로 모델 기반 테스트가 주로 사용되고 있는데, 반복과 동시성 작업을 포함하는 복잡한 시스템의 경우 경로 폭발을 야기하기 쉬운 문제가 있다. 특히 동시성 작업의 경우 Thread가 추가될수록 기하급수적인 수의 테스트 시나리오가 발생하게 되는데, 기존의 방법으로는 이를 해결하기 어렵다는 문제가 있다. 본 논문에서는 동시성 경로가 가지는 작업적 특성에 주안점을 두고, 이를 탐색하는 새로운 기법으로 경로 폭발 문제를 회피하는 방법을 제안한다. 사례 연구에서는 동시성 작업을 포함하는 시스템을 액티비티 다이어그램으로 표현하고, 기존의 기법이 생성할 테스트 시나리오의 수와 비교하여 본 기법의 효과를 보인다. 본 방법은 적은 수의 테스트 시나리오를 통해 반복과 동시성 작업의 결함을 효과적으로 발견할 것임을 기대한다. Currently, software testing is becoming increasingly important in the industrial field and a large body of research supports the improvement of efficient software testing. Model-based testing is generally used to formalize user requirement data for test design. Complex system that includes loop and concurrency has a high probability of path explosion problem. Specially, as threads are added to concurrency, test scenarios have also increased exponentially. However, it is difficult to solve this problem using existing techniques. In this paper, we propose novel path-search technique that focuses on behavioral features of concurrency path in order to avoid path explosion problem. A system that contains concurrent paths is represented by activity diagram in case study section. Efficiency of our study is shown through comparison with several generated test scenarios of other studies. The result indicate that our approach is efficient for finding faults in loop and concurrency with fewer test scenario.
DramaQA: 계층적 질의응답과 함께하는 등장인물 중심 비디오 스토리 이해
최성호(Seongho Choi),온경운(Kyoung-Woon On),허유정(Yu-Jung Heo),장유원(Youwon Jang),서아정(Ahjeong Seo),이승찬(Seungchan Lee),이민수(Minsu Lee),장병탁(Byoung-Tak Zhang) 한국정보과학회 2021 정보과학회 컴퓨팅의 실제 논문지 Vol.27 No.1
본 논문은 비디오 스토리의 포괄적 이해를 위한 새로운 비디오 질의응답 데이터셋 DramaQA를 제안한다. DramaQA 데이터셋은 1) 인간지능의 인지 발달 단계에 기초한 인공지능 시스템에 대한 평가 지표로서의 계층적 질의응답 데이터셋과 2) 스토리의 지역적 일관성을 모델링하기 위한 등장인물 중심의 비디오 주석을 제공하는 것을 목표로 한다. DramaQA 데이터셋은 TV 드라마 “또 오해영”을 이용하여 제작되었으며, 23,928개의 다양한 길이의 비디오로부터 각각 4개의 난이도 중 하나에 포함되는 17,983개의 질의응답 쌍을 포함한다. 데이터셋은 등장인물 중심 시각적 주석이 되어있는 217,308장의 이미지들과 상호참조가 해결된 스크립트를 제공한다. 또한, 우리는 비디오 질의응답에 대한 등장인물중심의 표현을 효과적으로 학습하기 위한 Dual Matching Multistream 모델을 제안하고 DramaQA 데이터셋에 적용하여 등장인물 중심의 비디오 스토리 이해 방법을 제시한다. In this paper, we propose a novel video question answering (Video QA) task, DramaQA, for obtaining a comprehensive understanding of a video story. The DramaQA focuses on two perspectives: 1) hierarchical QAs as an evaluation metric based on the cognitive developmental stages of human intelligence, and 2) character-centered video annotations to model the local coherence of the story. Our dataset is built upon the TV drama “Another Miss Oh” and contains 16,191 QA pairs from 23,928 video clips of various lengths, with each QA pair belonging to one of four difficulty levels. We provide a total of 217,308 annotated images with rich character-centered visual annotations and coreference resolved scripts. In addition, we provide analyses of the dataset as well as a Dual Matching Multistream model which effectively learns character-centered representations of the video to answer questions about the video.
Han Sungpil,Choi Hee Youn,Kim Yo Han,Choi SeungChan,Kim Seokuee,Nam Ji Yeon,Kim Bongtae,Song Geun Seog,Lim Hyeong-Seok,Bae Kyun-Seop 거트앤리버 소화기연관학회협의회 2023 Gut and Liver Vol.17 No.1
Background/Aims: Tegoprazan, a novel potassium-competitive acid blocker, is expected to overcome the limitations of proton pump inhibitors and effectively control nocturnal acid breakthrough. To evaluate the pharmacodynamics of tegoprazan versus dexlansoprazole regarding nocturnal acid breakthrough in healthy subjects. Methods: In a randomized, open-label, single-dose, balanced incomplete block crossover study, 24 healthy male volunteers were enrolled and randomized to receive oral tegoprazan (50, 100, or 200 mg) or dexlansoprazole (60 mg) during each of two administration periods, separated by a 7- to 10-day washout period. Blood samples were collected for pharmacokinetic parameter analysis; gastric monitoring was performed for pharmacodynamic parameter evaluation. Results: All 24 subjects completed the study. Average maximum plasma concentration, area under the plasma concentration–time curve, and mean time with gastric pH >4 and pH >6 for tegoprazan demonstrated dose-dependent incremental increases. All the tegoprazan groups reached mean pH ≥4 within 2 hours, whereas the dexlansoprazole group required 7 hours after drug administration. Based on pharmacodynamic parameters up to 12 hours after evening dosing, 50, 100, and 200 mg of tegoprazan presented a stronger acid-suppressive effect than 60 mg of dexlansoprazole. Moreover, the dexlansoprazole group presented a comparable acid-suppressive effect with the tegoprazan groups 12 hours after dosing. Conclusions: All the tegoprazan groups demonstrated a significantly faster onset of gastric pH increase and longer holding times above pH >4 and pH >6 up to 12 hours after evening dosing than the dexlansoprazole group.