Influence of Quaternization on UCST Properties of Hydroxyl-Derivatized Polymers

이형일 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.10

A series of hydroxyl-derivatized quaternized polymers were successfully synthesized by atom transfer radical polymerization (ATRP) and Cu(I)-catalyzed 1,3-dipolar cycloaddition of azide and alkynes (click chemistry), followed by quaternization reactions. ATRP was employed to synthesize poly(2-hydroxyethyl methacrylate) (PHEMA), followed by introduction of alkyne groups using pentynoic acid, leading to HEMA-Alkyne. 2- Azido-1-ethanol and 3-azido-1-propanol were combined with the HEMA-Alkyne backbone via click reaction, resulting in triazole-ring containing hydroxyl-derivatized polymers. Quaternization reactions with methyl iodide were conducted on the triazole ring of each polymer. Molecular weight, molecular weight distribution, and the degree of quaternization (DQ) were determined by gel permeation chromatography (GPC) and 1H NMR spectroscopy. The average molecular weight (Mn) of the resulting polymers ranged from 5.9 × 104 to 1.05 × 105 g/mol depending on the molecular architecture. The molecular weight distribution was low (Mw/Mn = 1.26-1.38). The transmission spectra of the 0.1 wt % aqueous solutions of the resulting quaternized polymers at 650 nm were measured as a function of temperature. Results showed that the upper critical solution temperature (UCST) could be finely controlled by the level of DQ.

점용접시편의 극한하중과 피로특성에 관한 실험적 고찰

이형일,김남호,이태수,Lee, Hyeong-Il,Kim, Nam-Ho,Lee, Tae-Su 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.1

The study on the mechanical behavior of a spot-welded specimen is largely divided into the quasi-static overload failure analysis and the fatigue failure prediction. The main issue in an overload analysis is to examine the critical loads, thereby providing a generalized overload failure criterion. As the welding spot forms a singular geometry of an external crack type, fatigue failure of spot-welded specimens can be evaluated by means of a fracture parameter. In this study, we first present the limit loads of 4 representative types of single spot-welded specimens in terms of the base metal yield strength and specimen geometries. Recasting the load vs. fatigue life relationships experimentally, obtained here, we then predict the fatigue life of spot-weld specimens with a single parameter denoted the equivalent stress intensity factor. This crack driving parameter is demonstrated to successfully describe the effects of specimen geometry and loading type in a comprehensive manner. The suggested fatigue life formula for a single spot weld can play a key, role in the design and assessment of spot-welded panel structures, in that the fatigue strength of multi-spots is eventually determined by the fatigue strength of each single spot.

$C^{\ast}$-적분에 기초한 고온배관 수명평가

이형일,Lee Hyungyil 한국가스학회 2000 한국가스학회지 Vol.4 No.4

In recent years, the subject of remaining life assessment has drawn considerable attention in power plants, where various structural components typically operate at high temperature and pressure. Thus a life prediction methodology accounting for high temperature creep fracture is increasingly needed for the components. Critical defects in such structures are generally found in the form of semi-elliptical surface crack, and the analysis of which is consequently an important problem in engineering fracture mechanics. On this background, we first develop an auto mesh generation program for detailed 3-D finite element analyses of axial and circumferential semi-elliptical surface cracks in a piping system. A high temperature creep fracture parameter $C^{\ast}$-integral is obtained from the finite element analyses of generated 3-D models. Post crack growth module is further appended here to calculate the amount of crack growth. Finally the remaining lives of surface cracked pipes for various analytical parameters are assessed using the developed life assessment program. 최근 들어 가혹한 온도 및 압력조건에서 운전이 요구되는 고온배관들의 잔여수명예측은 상당히 중요한 관심사로 부각되고 있다. 이에 고온손상을 정량적으로 평가하여 설비를 안전하게 사용하기 위한 유지기술 및 수명평가 기술을 확보하는 것은 매우 중요하다. 한편 이러한 고온배관내 대부분의 균열은 반타원 표면균열의 형태로 형상화되어 파괴역학의 실제응용에서 발견할 수 있는 가장 복잡한 형상과 하중특성을 갖게 된다. 이를 배경으로 본 연구에서는 먼저 축방향 및 원주방향 반타원 표면균열이 존재하는 직관의 완전 3차원 유한요소망 자동생성 프로그램을 작성하였다. 이렇게 생성된 유한요소 입력자료를 이용하여 3차원 유한요소 해석을 수행하면 반타원 표면균열선단을 따른 고온 크리프 파괴 지배변수 $C^{\ast}$-적분값을 구할 수 있다. 또한 $C^{\ast}$-적분값에 준해 균열진전량을 계산하는 후처리 균열진전 모듈을 추가하여 사용자 편의 수명평가 프로그램을 개발하였다. 최종적으로 개발된 통합 수명 평가 프로그램을 이용하여 여러 가지 해석변수들의 반타원 표면균열을 갖는 고온 직관 수명에 대한 영향을 살펴보았다.

특발성 안면신경 마비의 장기 추적 관찰

이형일,신정범,이상진,전포성,김경태 대한재활의학회 2005 Annals of Rehabilitation Medicine Vol.29 No.6

Objective: The purpose of this study was to observe clinical characteristics and electrodiagnostic findings of idiopathic facial palsy and to follow up beyond 1 year after onset. Method: From February 2002 to July 2003 the authors analyzed 103 cases that could be followed up after 1 year since diagnosed as idiopathic facial palsy by electrodiagnostic study which was performed at approximately 2 weeks after the onset time. The patients were classified by House- Brackmann (H-B) facial nerve grading system on their first visits and followed up by telephone interview using H-B system. Treatment method, age, sex, medical history and symptoms were noted. In addition, the blink reflex, nerveconduction study and needle electromyography (EMG) were done. Results: When degree of degeneration (% degeneration) was greater than 90% at approximately 2 weeks after the onset or motor unit action potentials were not detected in at least one among the four tested muscles, patients did not gain satisfactory facial function after 1 year. Conclusion: Methods related to prognosis of idiopathic facial palsy were compared with side to side evoked potential amplitude and needle EMG. This methods would be helpful to explain its prognosis.

Torsional vibration analysis of a planetary gear type antiresonant vibration isolator using transfer matrix method, Part II: Application to automotive powertrain

이형일,Hwan-Sik Yoon 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.3

In this research, an analytical modeling and analysis approach called the transfer matrix method is applied to study a planetary gear type dynamic antiresonant vibration isolator (PG-DAVI) for complex rotational systems. In this part 2 of series papers, the transfer matrix method is applied to an automotive powertrain system with an embedded PG-DAVI to characterize torsional vibration attenuation. First, the internal configuration of an automotive powertrain system is described as a baseline system, and its modal characteristics and harmonic responses are calculated. Then, two additional powertrain systems modified with a PG-DAVI and a classical dynamic absorber are presented. Finally, the effectiveness of vibration suppression in the powertrain system using a PG-DAVI is investigated by comparing the modal characteristics, harmonic responses, and time responses of the three powertrain configurations using the transfer matrix method as well as conventional analytical and numerical methods.

Torsional vibration analysis of a planetary gear type antiresonant vibration isolator using transfer matrix method, Part I: System modeling

이형일,Hwan-Sik Yoon 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.3

Recently, a new type of vibration isolator called a dynamic antiresonant vibration isolator (DAVI) has been studied for torsional systems as well as translational systems. In the DAVI for torsional systems, the inertia coupling for the anti-resonance effect is generated by a planetary gear that connects control inertia and inertias at the input and output terminals. In this research, an analytical modeling approach called the transfer matrix method is applied to design a planetary gear type DAVI for complex systems such as an automotive powertrain. Unlike a previous study, inertias of the pinion gears are newly included in the transfer matrix model to improve the model accuracy in this paper. In this part 1 of series papers, the internal configuration of a planetary gear type DAVI system is described and its dynamic model is derived using the transfer matrix method. The derived transfer matrix model is then validated by comparing its frequency response with those obtained by conventional and numerical methods. Finally, the effects of different gear ratios and pinion gear inertia are examined using the derived transfer matrix model.

J50 및 변형소성 파손곡선에 의한 원자로용기 안전여유 평가

이형일,손갑헌,김일 대한기계학회 1986 대한기계학회 춘추학술대회 Vol.- No.-

일본인의 한국어 발음에 나타난 피치 패턴 분석

이형재(李炯宰) 일본어문학회 2006 일본어문학회 국제학술대회 Vol.- No.-

점용접시편의 과부하해석 및 유효 J-적분에 의한 피로수명예측

이형일,최진용,Lee, Hyeong-Il,Choe, Jin-Yong 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.3

This paper proposes an integrated approach, which is independent of specimen geometry and loading type, for predicting the fatigue life of spot welded specimens. We first establish finite element models reflecting the actual specimen behaviors observed on the experimental load-deflection curves of 4 types of single spot welded specimens. Using finite element models elaborately established, we then evaluate fracture parameter J-integral to describe the effects of specimen geometry and loading type on the fatigue life in a comprehensive manner. It is confirmed, however, that J-integral concept alone is insufficient to clearly explain the generalized relationship between load and fatigue life of spot welded specimens. On this ground, we introduce another effective parameter $J_e$ composed of $J_I$, $J_{II}$, $J_{III}$, which has been demonstrated here to more sharply define the relationship between load and fatigue life of 4 types of spot welded specimens. The crack surface displacement method is adopted for decomposition of J, and the mechanism of the mixed mode fracture is also discussed in detail as a motivation of using $J_e$.

스포츠윤리와 태권도에 관한 연구

이형일,김학덕 한국웰니스학회 2011 한국웰니스학회지 Vol.6 No.3

The purpose of this study was to examine the ethical characteristics of Taekwondo which??has grown as the martial arts sports through the formation and the meaning of sports ethics. Thus, chapter 2??examined divergent views about the formation and meaning of sports ethics and the moral standard of sports??ethics. Chapter 3 firstly presented the examples which the ethical characteristics of Taekwondo made good character??development and secondly presented an empirical case of immoral and anti-social problems formed by??Taekwondo. Finally, this study examined two conclusions by reviewing sports ethics and moral characteristics of??Taekwondo. Firstly, Taekwondo was sports ethics as well as human existence is a real microcosm. Secondly, the way of??cultivating good moral attributes through Taekwondo could be explained by the habit in terms of empirical aspects.??Also, futures study need to explore how the definition of an ethical concept about Taekwondo players is applied to??martial arts sport through theoretical interpretation.