• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
• /
• pp.485-491
• /
• 1999

A burr is formed in every corner of parts as a result of machining, which produces undesirable edge geometry and influence deeply to surface quality of workpiece. Therefore these burrs must be removed certainly. The cost of removing these burrs is directly proportional to their size. Burrs have been among the most troublesome obstruction to high productivity and automation of machining processes. The proper selection of cutting condition and tool geometry will be helpful to reduce the occurrence of burrs. In paper will observe burr formation along helix angle in end milling and certificate experimentally mechanics relation of helix angle and burr formation.

• 한국공작기계학회논문집
• /
• 제13권2호
• /
• pp.17-24
• /
• 2004

In end milling process, undeformed chip thickness and cutting forces vary periodically with phase change of the tool. Recently, a model has been proposed to simulate the shear and friction characteristics of an up-end milling process in terms of the equivalent oblique cutting to this. In the current study, a down-end milling process has been replaced with the equivalent oblique cutting process. And shear and tool-chip friction characteristics variation of SM45C steel has been studied using the end-mills of different helix angles. The specific shear and friction energy consumed with helix angle of $50^{\circ}$ is somewhat larger than those of$30^{\circ}$ and $40^{\circ}$. The specific shear energy consumed is about 76-77% of the specific cutting energy regardless the helix angles.

• Kyungpook Mathematical Journal
• /
• 제56권3호
• /
• pp.1003-1016
• /
• 2016

In this paper, we introduce a new kind of slant helix for null curves called null $W_n$-slant helix and we give a definition of new harmonic curvature functions of a null curve in terms of $W_n$ in (n + 2)-dimensional Lorentzian space $M^{n+2}_1$ (for n > 3). Also, we obtain a characterization such as: "The curve ${\alpha}$ s a null $W_n$-slant helix ${\Leftrightarrow}H^{\prime}_n-k_1H_{n-1}-k_2H_{n-3}=0$" where $H_n,H_{n-1}$ and $H_{n-3}$ are harmonic curvature functions and $k_1,k_2$ are the Cartan curvature functions of the null curve ${\alpha}$.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.2460-2464
• /
• 2008

The present paper suggests new method to know the effects of molecular diffusion and the helicity of microchannel flows on mixing in passive micromixers, which are essential components of a microfluidic chip. In this study, 'Helix Index' is newly defined as the magnitude of chaotic advection. Relationship between Helix Index and Mixing Index is analyzed numerically such as the wide range of Peclet and Reynolds numbers in three dimensional serpentine microchannel when using soluble solutions (water/glycerol). As a result, a simple algebraic equation is derived by this relationship based on a regression analysis. The algebraic equation is found to be able to accurately predict the mixing performance without solving the coupled, complex momentum and mass transfer equations.

• Bulletin of the Korean Chemical Society
• /
• 제17권2호
• /
• pp.131-138
• /
• 1996

The conformational transition of oligopeptide multimer,-(HPPHPPP)n-, is studied (H:hydrophobic amino acid, P:hydrophilic amino acid). The helix/coil transitions are detected in the multimer. The transition depends on the number of amino acid in the sequence, the concentration of the oligopeptide, and temperature which affects helix stability constant (${\xi}$) and hydrophobic interaction parameter (wj). In the thermodynamic equilibrium system jA${\rightarrow}$Aj (where A stands for oligopeptide monomer), Skolnick et al., explained helix/coil transition of dimer by the matrix method using Zimm-Bragg parameters ${\xi}$ and $\sigma$ (helix initiation constant). But the matrix method do not fully explain dangling H-bond effects which are important in oligopeptide systems. In this study we propose a general theory of conformational transitions of oligopeptides in which dimer, trimer, or higher multimer coexists. The partition of trimer is derived by using zipper model which account for dangling H-bond effects. The transitions of multimers which have cross-linked S-S bonds or long chains do not occur, because they keep always helical structures. The transitions due to the concentration of the oligopeptides are steeper than those due to the chain length or temperature.

• Journal of Contemporary Eastern Asia
• /
• 제13권1호
• /
• pp.1-4
• /
• 2014

• 벤처창업연구
• /
• 제11권2호
• /
• pp.183-195
• /
• 2016

소상공인이 한국 경제에서 차지하는 비중이 높지만 전문적인 경영 역량이 부족하여 어려움에 처하는 경우가 많다. 그러나 이에 대한 실효성 있는 대안은 부족하다. 소상공인의 경영 문제에 관한 학계의 관심은 주로 성공적인 소상공인의 특징을 밝히거나 요인들 간의 관련성을 살펴보는 기술적이고 정량적 데이터 위주의 단편적 성과에 머물렀다. 한편 실질적인 경영 지원 과정을 통해 획득된 지식과 경험들을 이론적으로 논의하는 실천적 연구 성과는 찾아보기 어려운 형편이다. 2015년 6월부터 2015년 11월까지 경기도에 소재한 소상공인 업체들과 경기도 소재의 대학 및 경기도 소재의 중소기업진흥 기관이 공동으로 추진한 컨설팅 프로젝트에 실행 연구법을 부분 적용한 결과 트리플 힐릭스 이론 기반의 소상공인 컨설팅이 바람직한 결과를 가져온다는 사실을 알 수 있었다. 업체와 대학 그리고 공공 기관의 협업은 경영학을 배우는 학생들의 문제의식을 높이고 지식을 활용하는 기회를 부여하는 등 경영교육 상 목적 달성에 적절함도 확인했다.

• BMB Reports
• /
• 제28권3호
• /
• pp.221-226
• /
• 1995

Dopamine mediates inhibitory responses in Helix aspersa neurons from the right parietal lobe ("F-lobe") of the circumoesophageal ganglia. The effects appeared as a dose-dependent hyperpolarization of the plasma membrane and a decrease in the occurrence of spontaneous action potentials. The average hyperpolarization with 5 ${\mu}m$ dopamine was -12 mV (${\pm}1.5$mV, S.D., n=12). Dopamine also modulated the currents 'responsible for shaping the action potentials in these neurons. When dopamine was added and action potentials were triggered by an injection of current, the initial depolarization was slowed, the amplitude and the duration of action potentials were decreased, and the after-hyperpolarization was more pronounced. The amplitude and the duration of action potential were reduced about 15 mV and about 13% by 5 ${\mu}m$ dopamine, respectively. The effects of dopamine on the resting membrane potentials and the action potentials of Helix neurons were dose-dependent in the concentration range 0.1 ${\mu}m$ to 50 ${\mu}m$. In order to show 1) that the effects of dopamine were mediated by dopamine receptors rather than by direct action on ionic channels and 2) which type of dopamine receptor might be responsible for the various effects, we assayed the ability of mammalian dopamine receptor antagonists, SCH-23390 (antagonist of D1 receptor) and spiperone (antagonist of D2 receptor), to block the dopamine-dependent changes. The D1 and D2 antagonists partially inhibited the dopamine-dependent hyperpolarization and the decrease in action potential amplitude. They both completely blocked the decrease in action potential duration and the increase in action potential after-hyperpolarization. The dopamine-induced slowdown of the depolarization in the initial phase of the action potentials was less effected by SCH-23390 and spiperone. From the results we suggest 1) that Helix F-lobe neurons may have a single type of dopamine receptor that binds both SCH-23390 and spiperone and 2) that the dopamine receptor of Helix F-lobe neurons may be homologous with and primitive to the family of mammalian dopamine receptors.

• 한국인터넷방송통신학회논문지
• /
• 제16권5호
• /
• pp.229-233
• /
• 2016

본 논문에서는 4개의 유전자 핵염기 C, U(T), A, G를 행렬로 표시하고, $4{\times}4$ RNA(ribose nucleic acid)에서 $8{\times}8$ DNA(deoxyribose nucleic acid)로의 행렬 구조에 대해 서술한다. BCHJM (block circulant Hadamard-Jacket matrix)에 의해 DNA 이중나선 구조(double helix)를 해석한다. 직교 BCHJM은 비대칭 쌍 상보성(complementary)을 보이고 있다. 블록순환(block circulant) RNA 쌍 손상(damage) 신뢰성(reliability)은 기존 이중나선 보다 우수함을 보이고 있다. k=4, N=1인 경우 블록 순환 상보 쌍 신뢰도는 93.75%이고, k=4, N=4인 경우 신뢰도는 98.44%로 기존 이중나선의 경우 보다 4.69% 개선된다.

• 한국경제지리학회지
• /
• 제17권4호
• /
• pp.801-816
• /
• 2014

본 연구는 트리플 힐릭스 모형을 활용하여 싱가포르의 첨단생명과학단지에 대한 분석을 시도하였다. 트리플 힐릭스 모형의 이론적 논의와 현실에서의 산 학 관 관계의 차이점에 주목하고 연구문제를 제시하였다. 싱가포르 첨단 생명과학단지는 대학, 정부 그리고 기업체간의 삼자간 상호작용이 존재하고 있었지만, 트리플 힐릭스 모형의 이론적 틀과는 다르게 작동하고 있었다. 우선, 대학보다는 정부가 삼자간의 관계를 결정할 정도의 주도적인 역할을 하고 있었다. 정부는 이민정책, 장학금, 세금감면 및 세금이외의 인센티브 정책 등 생명과학 및 의료산업에 대한 포괄적인 지원 정책을 추진하였다. 또한 정부는 초기단계에서부터 삼자간 관계를 주도하였으며 이러한 역할은 클러스터가 어느 정도 진전된 이후에도 지속되고 있었다. 정부의 이러한 지원은 삼자간 상호작용을 가능하게 하는 추동력으로 작동하고 있었다.