Nonlinear Aspects of the Frequency Response of a Gas-filled Bubble Oscillator

김동혁,김정태,이용봉,Kim, Dong-Hyuk,Kim, Jeung-Tae,Lee, Yong-Bong The Acoustical Society of Korea 1991 韓國音響學會誌 Vol.10 No.1

기포 진동 시스템에 대한 수치해석이 수행되었다. 수학적 모델은 기포역학에 대해서는 Keller의 식을, 기포내부 해석을 위해서는 Prosperetti의 식을 채택하였다. Prosperetti는 기포내부 해석을 위해 에너지 방정식을 도입하였으며 매우 정확한 해석을 가능케 하였다. 수치해석결과 기포진동의 주파수 응답곡선에 있어 전형적인 비선형 현상들을 볼 수 있었다. 이러한 비선형 현상들에는 점프현상(jump phenomena), 공진주파수의 변화, 그리고 superharmonic 공진점의 발생등이 있다. 비선형 주파수 응답은 기포진동 시스템의 초기조건에 따라 달라지는데 이에 의해 어느 가진 주파수 대역에서는 두개 이상의 해가 존재할 수 있게 된다. 기포진동 시스템에서 비선형 진동현상은 Duffing 방정식과 비교가 되는데 두 시스템은 비슷한 비선형 현상들을 가지고 있다고 볼 수 있다. A numerical analysis is carried out for the nonlinear phenomena of the bubble oscillator. The model is based on the Keller's formulation for the bubble dynamics. Interpretation of the bubble interior is based on the formulation by Prosperetti. His formulation adopts the energy equation for the analysis of the bubble interior. The numerical simulation Shows typical nonlinear phenomena in its frequency response. Among such nonlinear aspects are the jump phenomenon, the shift of natural frequency of the system, and the appearance of superharmonic resonances. It is deduced that the nonlinear frequency response is dependent upon the initial condition of the bubble oscillator and some multi-valued frequency region can appear in the response curve. Nonlinear phenomena appeared in the bubble oscillator is compared with those of the Duffing equation and it may be said that the bubble dynamic equation has similar nonlinear aspects to the Duffing equation.

재활용 절삭칩으로 제조된 AC2B 합금의 용체화 열처리에 따른 미세조직 및 기계적특성 변화

김동혁,윤종천,최창영,최시근,홍명표,신상윤,예병준,Kim, Dong-Hyuk,Yoon, Jong-Cheon,Choi, Chang-Young,Choi, Si-Geun,Hong, Myoung-Pyo,Shin, Sang-Yoon,Ye, Byung-Joon 한국주조공학회 2018 한국주조공학회지 Vol.38 No.2

Changes in the microstructures and mechanical properties of an AC2B alloy through solution heat treatment were investigated using recycled AC2B cutting chips as raw material. The as-cast microstructure of the AC2B alloy comprised ${\alpha}$-Al, $Al_2Cu$, and coarse needle-shaped phases considered to be eutectic Si and an Al-Fe-Si based intermetallic compound. After solution heat treatments at $505^{\circ}C$ for 1 h and 6 h, the samples showed complete dissolution of $Al_2Cu$ and relatively fine distribution of intermetallic compounds. Hardness test results showed that the hardness rapidly increased after the solution heat treatment for 1 h by solid solution hardening, and the increase of hardness exhibited a plateau from 1 h to 6 h. The results of the hardness and tensile tests showed that there was no visible difference in the effect of 1 h and 6 h solid solution treatment.

웹을 기반으로 한 자기 주도적 MITS -초등 수학 수와 연산 영역 중심-

김동혁,고병오,최의인,Kim, Dong-Hyuk,Goh, Byung-Oh,Choi, Eui-In 한국정보교육학회 2004 정보교육학회논문지 Vol.8 No.3

Recently, there is change the environment of education due to development of Science Technology Specially, As education information on web increased by internet, using education web data by mean of medium that aids learning by computer. Also It studied method that used the Computer as learning medium through the CAI(Computer Assisted Instruction), ICAI(Intelligent CAI), and ITS(Intelligent Tutoring System). But legacy system are not support efficient method that learns to vary learner suitable learning method by individual level. Specially It is not suitable the education course to direct current course of education, and not consider different of student capability, aptitude, need, interesting, not maximized the individual growable power and effect of education. To solve the this problem, our paper suggest the web-based self-directed MITS(Multimedia ITS) that supply the needed the information on web, make the environment that can self-directed learning. To maximized effect of individual learning, our paper structured coursed, characterized, related learning contents in region of numeral at mathematics of primary school. And then integrated contents and class, design and implement the web-based MITS that consist of 4 module to escape from limitation of learner grade, learning time, learning place.

성서 본문의 언어학적 연대 결정에 관한 논쟁과 언어 변이성 개념에 근거한 그 이론적 평가

김동혁(Dong-Hyuk Kim) 한국신학정보연구원 2012 Canon&Culture Vol.6 No.2

본 소고는 구약 성서 본문의 언어학적 연대 결정에 대한 최근의 논쟁을 정리하고 그 논쟁을 사회 언어학의 언어 변이성(linguistic variability) 개념을 토대로 이론적으로 평가한다. 후르비츠(Avi Hurvitz)와 그를 따르는 학자들의 전통적인 의견은 초기 성서 히브리어와 후기 성서 히브리어가 그 형태와 시기에 있어서 단절되므로 성서 본문의 연대를 언어학적 증거만을 사용해서 결정하는 것이 가능하다는 것이다. 반면 영(Ian Youong), 레젯코(Robert Rezetko), 에렌스베르드(Martin Ehrensvard) 등은 초기 성서 히브리어와 후기 성서 히브리어는 그 형태와 시기에 있어서 완전히 단절되지 않기 때문에 성서 본문의 연대를 언어학적 증거만을 사용해서 결정하는 것은 불가능하다고 주장한다. 이들은 더 나아가 초기 성서 히브리어와 후기 성서 히브리어는 포로기 이후 성서 기자들이 자유롭게 선택할 수 있었던 동시대의 스타일일 뿐이라고 주장한다. 논쟁의 핵심은 초기 성서 히브리어와 후기 성서 히브리어가 언어 변이를 통해서 구분된다는 점이다. 사회 언어학에서는 모든 언어 변화는 언어 변이를 통해서만 일어난다는 점을 설득력 있게 규명하였는데 이를 토대로 본 소고는 다음 두 가지를 주장한다. 첫째, 언어 변이를 통해서 규정되는 초기 성서 히브리어와 후기 성서 히브리어는 동시대의 스타일이라기보다는 연대에 따른 언어 변화의 결과라고 보는 것이 더 타당하다. 둘째, 언어 변화가 언어 변이를 통해서만 일어난다는 사실은 변화의 양상이 일시적이지도 않고 통일적이지도 않다는 의미이다. 따라서 초기 성서 히브리어와 후기 성서 히브리어의 프로파일만을 가지고 어떤 한 본문의 연대를 결정하는 것은 방법론적으로 옳지 못하다. 즉, 성서 본문의 연대를 언어학적 증거만을 가지고 결정하는 것은 이론적으로 불가능하다. The present paper surveys the debate over the linguistic dating of biblical texts and attempts to evaluate it theoretically on the basis of the sociolinguistic concept of linguistic variability. The traditional understanding, proposed by Avi Hurvitz and supported by his followers, is that Early Biblical Hebrew(EBH) and Late Biblical Hebrew(LBH) are distinct in form and in chronology and that it is possible to date a biblical text by using only linguistic data. On the other hand, scholars such as Ian Young, Robert Rezetko, and Martin Ehrensvard argue that EBH and LBH are not distinct in form and in chronology and so it is impossible to date a biblical text by using only linguistic data. They further maintain that EBH and LBH are two contemporary styles from which the postexilic biblical writers were free to choose. At the center of the debate is the fact that EBH and LBH are in many cases defined by linguistic variation. Sociolinguists have demonstrated that linguistic change occurs only through linguistic variation. On the basis of this understanding, the present study argues the following: First, EBH and LBH, which are defined by linguistic variation, are rather two phases of linguistic change of the biblical period than contemporary styles. Second, that linguistic change occurs only through the state of linguistic variation entails that the change is never instantaneous or uniform. Thus it is methodologically not valid to date a biblical text on the basis of the profile of LBH or of EBH. In other words, the linguistic dating of biblical texts is theoretically impossible.

영어와 성서 히브리어의 몇 가지 문법 용어에 대한 한국어 번역 제안

김동혁(Dong-Hyuk Kim) 대한성서공회 2016 성경원문연구 Vol.- No.39

The present study investigates some grammatical terms in English and Biblical Hebrew (BH), and their Korean translations that may cause misunderstanding: adjective and its translation hyeongyongsa (형용사), verb and its translation dongsa (동사), and stative verb and fientive verb and their translations sangtae dongsa (상태 동사) and dongjak dongsa (동작 동사). The study argues that the grammatical concepts that the English expressions refer to in English and BH differ from the ones that the Korean expressions refer to in Korean. First, adjectives in English and BH differ from hyeongyongsas in Korean. Morphologically, adjectives decline whereas hyeongyongsas conjugate. Syntactically, adjectives require a copula to be a predicate while hyeongyongsas need an ending. Therefore, rather than translating adjective as hyeongyongsa, it seems better to invent a new expression like sogseongsa (속성사). Second, the category called verb in many languages including English and BH is generally translated as dongsa in Korean. In English, BH, and many other languages, verbs are understood to conjugate morphologically and to be able to be a predicate syntactically. On the other hand, Korean dongsas should meet an additional condition: the fientive meaning. Therefore, the category of verbs and that of dongsas do not overlap well enough, and the latter is not a satisfactory translation of the former. The study suggests seosulsa (서술사) as an alternative. Third, verbs are grouped into fientive verbs and stative ones, generally translated as dongjak dongsa and sangtae dongsa. Following the foregoing discussion, dongjak seosulsa (동작 서술사) and sangtae seosulsa (상태 서술사) are to be preferred.

넷퍼넬을 이용한 웹서비스 과부하 방지 구현

김동혁(Dong-Hyuk Kim),문현구(Hyun-Koo Moon),신현근(Hyun-Geun Shin),박건훈(Gun-Hoon Park),김설아(Seol-A Kim),강민정(Min-Jeong Gang),조성훈(Seong-Hoon Jo),임양원(Yangwon Lim),임한규(Hankyu Lim) 한국정보과학회 2014 한국정보과학회 학술발표논문집 Vol.2014 No.6

1962년 노보체르카스크(Новочеркасск) 노동자 봉기의 발생과 심화 원인에 대한 재고

김동혁(Kim, Dong-Hyuk) 효원사학회 2021 역사와 세계 Vol.- No.59

형사절차와 인권보장 ; 피해자 고소권의 법적 쟁점 -피해자의 고소적격을 중심으로-

김동혁 ( Dong Hyuk Kim ) 한국경찰법학회 2014 경찰법연구 Vol.12 No.2

Accused of a crime have the right to harm the victim party should of course say that the rights will be retained. In addition, victims of crime are generally social, legal, because it will often victims, which stands for the country`s citizens have a basic right to stand complaint should be addressed. Therefore, the concept of crime victims as a subject of complaint is not to be interpreted as limiting sense. 41) Thus, the ability of the civil action complaint by the ability of families without requiring that the de facto ability should see a doctor. Ability to conduct judicial recognition of the award, so it is widely recognized sense. We are also cases of adultery and obstruction of official business and legal interests, such as social and national legal interests complaint is recognized even if the infringement, and that victims are recognized based on the concept of complaint range “means a crime or act of the other party, including should be interpreted. Thus, the social and legal interests of national personal legal interests for the sinner. On the other hand, the concept of the victim must be a victim of the legal implications. For example, the lion victim of libel relatives or descendants of victims should be legal sense. complaint a legal concept, and therefore requires that the legal status because it should . The interpretation of the concept of the victims of these victims complaint zoom events and at the same time to ensure the legality of the exercise will help you efficiently.

알루미늄 함량에 따른 AGI (Austempered Gray Cast Iron)의 오스테나이트 형성 및 기계적 특성에 관한 연구

김동혁 ( Dong-hyuk Kim ) 한국주조공학회 2021 한국주조공학회지 Vol.41 No.6

알루미늄 주철은 내산화성, 내황화성 및 부식성이 우수하다. Ti, Ni 합금에 비해 비전략적 원소인 Fe를 사용하는 비용이 상대적으로 저렴하여 구조재 및 스테인리스강의 대체재로 기대되고 있다. 이는 스테인리스 스틸을 사용하는 경우에 비해 약 30%의 중량 감소 효과를 가져온다. 알루미늄 합금의 경우 최근 몇 년간 주철의 합금원소로 널리 사용되고 있는 원소이다. 실온에서 연성이 부족하고 600℃를 초과하면 강도가 급격히 감소하여 실용화가 지연되었다. 실온 연성이 약한 원인은 수소에 의한 환경 취화로 알려져 있으며, 이러한 특성의 약점을 개선하기 위해 다양한 합금원소의 첨가가 시도되고 있다. 회주철의 경도와 내마모성을 높이기 위해 주로 바나듐, 크롬, 망간 등의 합금원소를 사용하고 있지만, 이러한 원소를 포함하는 완제품의 가격과 합금화의 문제는 많은 한계가 있다. Aluminum cast iron has excellent oxidation resistance and good resistance to sulfide and corrosion. Compared to Ti and Ni alloys, it is expected to be a substitute material for structural materials and stainless steels because it is relatively inexpensive to use Fe, which is a non-strategic element. This results in a weight reduction effect of about 30% as compared to the use of stainless steel. With regard to aluminum as an alloying material, it is an element that has been widely used for the alloying of cast iron in recent years. Practical use has been delayed owing to the resulting lack of ductility at room temperature and the sharp decrease in the strength above 600℃ of this alloy, however. The cause of the weak room temperature ductility is known to be environmental embrittlement by hydrogen, and the addition of various alloying elements has been attempted in order to mitigate these shortcomings. Although alloying elements such as vanadium, chromium, and manganese are mainly used to increase the hardness and wear resistance of gray cast iron, the price of finished products containing these elements and the problems associated with alloys with this material impose many limitations.

모세의 에티오피아 원정: 아르타파노스와 요세푸스 비교 연구

김동혁(Dong-Hyuk Kim) 한국구약학회 2021 구약논단 Vol.27 No.1

This article compares and contrasts two Hellenistic versions of the story of Moses’s Ethiopian campaign, the version of Artapanus (Praep. ev. 9.27.7-16) and that of Josephus (A.J. 2.238-257), so that it may investigate how the same motif was expressed differently in Hellenistic Egypt and in Eretz Israel and what roles each version played in its own setting. The study makes comparisons of each of the stages of the two stories. Then, it synthesizes the results and discusses the origin, purpose, and audience of Artapanus’s and Josephus’s versions of the story of Moses’s campaign against Ethiopia. Artapanus’s story is a “competitive historiography” originating from Hel lenistic Egypt. Since he wants his writing to be apologetic and polemic, Artapanus uses biblical and other sources freely. He portrays Moses as a national hero of Egypt and a founder of its culture so that he may correct contemporary anti-Jewish sentiments among non-Jews and enhance the self-esteem of Jews. Josephus’s story is not as polemic as Artapanus’s. He is not as free as Artapanus in adapting biblical sources, probably because his main purpose was to write a history as accurately as possible. Although Josephus must have wanted his writing to reach non-Jews, his attention seems to have been directed more toward Jews than non-Jews. This study helps take an in-depth look at the time, society, and people of each of the matrices where the same motif about a Jewish hero was made, developed, and circulated.