• 제목/요약/키워드: Fundamental group

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STRUCTURES OF GEOMETRIC QUOTIENT ORBIFOLDS OF THREE-DIMENSIONAL G-MANIFOLDS OF GENUS TWO

  • Kim, Jung-Soo
    • 대한수학회지
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    • 제46권4호
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    • pp.859-893
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    • 2009
  • In this article, we will characterize structures of geometric quotient orbifolds of G-manifold of genus two where G is a finite group of orientation preserving diffeomorphisms using the idea of handlebody orbifolds. By using the characterization, we will deduce the candidates of possible non-hyperbolic geometric quotient orbifolds case by case using W. Dunbar's work. In addition, if the G-manifold is compact, closed and the quotient orbifold's geometry is hyperbolic then we can show that the fundamental group of the quotient orbifold cannot be in the class D.

3-DIMENSIONAL NON-COMPACT INFRA-NILMANIFOLDS

  • Kim, Ki-Heung;Im, Sung-Mo
    • 대한수학회지
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    • 제36권1호
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    • pp.1-13
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    • 1999
  • Let G be the 3-dimensional Heisenberg group. A discrete subgroup of Isom(G), acting freely on G with non-compact quotient, must be isomorphic to either 1, Z, Z2 or the fundamental group of the Klein bottle. We classify all discrete representations of such groups into Isom(G) up to affine conjugacy. This yields an affine calssification of 3-dimensional non-compact infra-nilmanifolds.

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MATRIX PRESENTATIONS OF THE TEICHMÜLLER SPACE OF A PAIR OF PANTS

  • KIM HONG CHAN
    • 대한수학회지
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    • 제42권3호
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    • pp.555-571
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    • 2005
  • A pair of pants $\Sigma(0,3)$ is a building block of oriented surfaces. The purpose of this paper is to formulate the matrix presentations of elements of the Teichmuller space of a pair of pants. In the level of the matrix group $SL(2,\mathbb{R})$, we shall show that an odd number of traces of matrix presentations of the generators of the fundamental group of $\Sigma(0,3)$ should be negative.

냉온 부하에 따른 요골동맥 맥파의 변화 특성을 파악하기 위한 무작위 배정·2×2교차설계 탐색적 임상시험계획서 개발 (Development of Clinical Protocol for Acquisition of Change of Radial Pulse Wave Signal in the Cold-Heat Intervention: Explanatory, Randomized, 2×2 cross-over design)

  • 유하나;김지혜;구본초;김현호;전영주
    • 대한한의진단학회지
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    • 제19권2호
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    • pp.91-100
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    • 2015
  • Objectives The aim of this study is to develop a structured clinical protocol related with acquisition of radial pulse wave in the randomized, $2{\times}2$ cross-over design, and cold-heat intervention trial for a pilot and preliminary study. Methods The protocol was contrived based on wide ranging literature searches for cold-heat intervention experiments and radial pulse diagnoses. Results Sample size of 60 subjects was calculated based on an effect size derived from the previous study designed to detect the pre-post cold-heat differences in the radial pulse. Each subjects will be randomly assigned to the cold (first) to heat (last) group (n=30) or heat (first) to cold (last) group (n=30). All subjects will fill out a case report form and questionnaires related with pattern identification, dietary patterns, sleep quality, and physical activity will be surveyed and used as a secondary outcomes. Safety assessment will be reported at the final stage. Conclusions This protocol will provide an additional reference to future studies related with observation of radial pulse during any interventions and also expect to be used as a guideline for acquisition of reliable radial pulse wave data.

The simulation study on natural circulation operating characteristics of FNPP in inclined condition

  • Li, Ren;Xia, Genglei;Peng, Minjun;Sun, Lin
    • Nuclear Engineering and Technology
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    • 제51권7호
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    • pp.1738-1748
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    • 2019
  • Previous research has shown that the inclined condition has an impact on the natural circulation (natural circulation) mode operation of Floating Nuclear Power Plant (FNPP) mounted on the movable marine platform. Due to its compact structure, small volume, strong maneuverability, the Integral Pressurized Water Reactor (IPWR) is adopted as marine reactor in general. The OTSGs of IPWR are symmetrically arranged in the annular region between the reactor vessel and core support barrel in this paper. Therefore, many parallel natural circulation loops are built between the core and the OTSGs primary side when the main pump is stopped. and the inclined condition would lead to discrepancies of the natural circulation drive head among the OTSGs in different locations. In addition, the flow rate and temperature nonuniform distribution of the core caused by inclined condition are coupled with the thermal hydraulics parameters maldistribution caused by OTSG group operating mode on low power operation. By means of the RELAP5 codes were modified by adding module calculating the effect of inclined, heaving and rolling condition, the simulation model of IPWR in inclined condition was built. Using the models developed, the influences on natural circulation operation by inclined angle and OTSG position, the transitions between forced circulation (forced circulation) and natural circulation and the effect on natural circulation operation by different OTSG grouping situations in inclined condition were analyzed. It was observed that a larger inclined angle results the temperature of the core outlet is too high and the OTSG superheat steam is insufficient in natural circulation mode operation. In general, the inclined angle is smaller unless the hull is destroyed seriously or the platform overturn in the ocean. In consequence, the results indicated that the IPWR in the movable marine platform in natural circulation mode operation is safety. Selecting an appropriate average temperature setting value or operating the uplifted OTSG group individually is able to reduce the influence on natural circulation flow of IPWR by inclined condition.

구조물 건전성 모니터링을 위한 Lamb파 모드 구별법 (A Method of Lamb-Wave Modes Decomposition for Structural Health Monitoring)

  • 전용주;박일욱;이우식
    • 한국정밀공학회지
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    • 제29권8호
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    • pp.887-895
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    • 2012
  • Lamb waves have received a great attention in the structural health monitoring (SHM) societies because they can propagate over relatively large distances in wave guides such as thin plates and shells. The time-of-flights of Lamb waves can be used to detect damages in a wave guide. However, due to the inherent dispersive and multi-mode characteristics of Lamb waves, one must decompose the Lamb wave modes into the symmetric and anti-symmetric modes for SHM applications. Thus, this paper proposes a decomposition method for the two-mode Lamb waves based on two rules: the group velocity ratio rule and the mode amplitude ratio rule. The group velocity ratio rule means that the ratio of the group velocities of fundamental symmetric and anti-symmetric modes is constant, while the mode amplitude ratio rule means that the magnitude of the fundamental symmetric modes of all measured response signals should be always larger than those of the anti-symmetric mode once the input signal is applied so that the magnitude of fundamental symmetric mode of excited Lamb-wave is larger than that of anti-symmetric mode, and vice versa. The proposed method is verified through the experiments ducted for an aluminum plate specimen.

Incorporation of Brainteaser Game in Basic Organic Chemistry Course to Enhance Students' Attitude and Academic Achievement

  • Cha, Jeongho;Kan, Su-Yin;Wahab, Nurul Huda Abdul;Aziz, Ahmad Nazif;Chia, Poh Wai
    • 대한화학회지
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    • 제61권4호
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    • pp.218-222
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    • 2017
  • Game shows are capable of grabbing students' attention in a lecture, and at the same time offers much delight to students to learn in a more interesting and entertaining way. A mind game was developed and incorporated into the teaching of basic organic chemistry course at the Universiti Malaysia Terengganu. The modified brainteaser game is comprised of a set of problems associated with vocabulary or concepts in basic organic chemistry, whereby students were required to solve within a stipulated time frame. Students' attitude changes were then evaluated with the administration of Attitude toward the Subject of Chemistry Inventory Version 2 (ASCIv2) questionnaire. The result of this study revealed that the intervention group experienced a significant change in attitude towards the course as compared to the control group. The intervention group also experienced a positive learning environment, resulting in an increased academic performance and interest.

3온스 물 삼킴검사 이후 정상 노년층의 음질 변화: 음향학적 분석 (Voice quality of normal elderly people after a 3oz water-swallow test: An acoustic analysis)

  • 이솔희;최홍식;최성희;김향희
    • 말소리와 음성과학
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    • 제10권2호
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    • pp.69-76
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    • 2018
  • The elderly are at increased risk of developing dysphagia due to aging and illnesses. The aim of the current study was to analyze, via an acoustic study, the change in the voice quality of normal elderly people after a 3oz water-swallow test. Subjects included a group of 60 normal elderly people (age: $mean{\pm}SD=76.9{\pm}6.66$) and 60 healthy young adults (age: $mean{\pm}SD=25.1{\pm}2.36$). Every participant produced a five-second /a/ phonation pre- and post-swallowing, and the fractioned two-second sections were analyzed using the MDVP (multi dimensional voice program) analysis. The elderly group demonstrated a post-swallowing increase in the following related acoustic parameters: fundamental frequency, fundamental frequency variation, amplitude-variation, and noise in both two-second sections. However, the younger group showed an increase only in frequency related acoustic parameters (i.e., STD ) in the first two-second section. The significant changes in values in the post-swallowing parameters might indicate temporary irregularities in pitch and amplitude along with higher amounts of noise in the voice. The results could be attributed to water residues in the vocal fold and vocal tract, as well as a deterioration of the motor and sensory functions caused by anatomical and physiological changes that result from aging.

보건소 고혈압관리 교육사업의 평가적 연구 (An Evaluative Study of Health Education Programs for Community-based Hypertension Control in Public Health Centers)

  • 이인숙
    • 지역사회간호학회지
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    • 제15권4호
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    • pp.517-527
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    • 2004
  • Purpose: This research is to find a solution for educational work on high blood pressure control in public health centers by analyzing their current status. Method: It analyzed data from 133 public health centers that had been doing educational work on high blood pressure, through a questionnaire. Also, it developed recommendations by converging opinions from an expert group made of 25 people with nominal group technique. Result: The educational methods of public health centers did not make any approach to get to the goal of the work. The mass media education and campaign activities for the general public had just temporary and passive propensities. In education for patients, it did not use appropriate methods to present management techniques for diagnosis process of patients, medication management, self monitoring BP, and risk factors. Pocket book for monitoring high blood pressure was not focused on self-recording for self-management. The expert group recommended that educational materials for adults should be developed focusing on treatments and observance of risk factors through daily living, and those for children should be focused on basic understanding about diseases, and life style. Conclusion: Presenting direction and strategy of fundamental education work is needed for public health centers by giving them standard educational guidelines of managing high blood pressure nationally, and it is desirable that fundamental frameworks of educational materials should be developed and distributed by professional groups nationally.

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Continuous Wavelet Transform을 단주기 레일리파에 적용하여 구한 천부지반 S파 속도구조 (The S-wave Velocity Structure of Shallow Subsurface Obtained by Continuous Wavelet Transform of Short Period Rayleigh Waves)

  • 정희옥;이보라
    • 한국지구과학회지
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    • 제28권7호
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    • pp.903-913
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    • 2007
  • 천부지반에서 레일리파의 군속도와 위상속도 분산곡선을 역산하여 S파 속도구조를 구하는 방법을 비교하였다. 위상속도를 구하기 위해서 ${\tau}-p$ stacking 방법을 이용하였고, 군속도를 구하기 위해서 두 가지 방법, multiple filtering technique(MFT) continuous wavelet transform(CWT) 방법을 사용하였다. 고차모드가 존재하는 경우, 위상속도에서 기본모드와 고차모드를 분리하기가 용이하지 않았고, 군속도에서는 continuous wavelet transform 방법이 multiple filtering technique보다 효과적이었다. S파 속도 역산 결과, 위상속도와 군속도의 기본 모드만 역산할 경우, 신뢰구간의 깊이가 아주 얕았다. Continuous wavelet transform으로 구한 기본 모드와 1차 모드를 동시 역산할 경우, 신뢰구간의 깊이가 2배 이상 증가함을 알 수 있었다. 이는 1차 모드의 에너지가 더 깊은 층을 통과함으로 깊은 층에 대한 5파 속도 정보를 지니고 있기 때문으로 보인다. 위의 방법을 서해안 동호항의 조간대에 적용하여, continuous wavelet transform으로 구한 군속도의 기본 모드와 1차 모드를 동시 역산하여 S파 속도구조를 구하고, 해당 지역의 시추조사 결과와 비교하였다.