• 제어로봇시스템학회논문지
• /
• 제10권12호
• /
• pp.1164-1171
• /
• 2004

A new multi-scale simulation model is proposed to analyze heart mechanics. Electrophysiology of a cardiac cell is numerically approximated using the previous model of human ventricular myocyte. The ion transports across cell membrane initiated by action potential induce an excitation-contraction mechanism in the cell via cross bridge dynamics. Negroni and Lascano model (NL model) is employed to calculate the tension of cross bridge which is closely related to the ion dynamics in cytoplasm. To convert the tension on cell level into contraction force of cardiac muscle, we introduce a simple geometric model of ventricle with a thin-walled hemispheric shape. It is assumed that cardiac tissue is composed of a set of cardiac myocytes and its orientation on the hemispheric surface of ventricle remains constant everywhere in the domain. Application of Laplace law to the ventricle model enables us to determine the ventricular pressure that induces blood circulation in a body. A lumped parameter model with 7 compartments is utilized to describe the systemic circulation interacting with the cardiac cell mechanism via NL model and Laplace law. Numerical simulation shows that the ion transports in cell level eventually generate blood hemodynamics on system level via cross bridge dynamics and Laplace law. Computational results using the present multi-scale model are well compared with the existing ones. Especially it is shown that the typical characteristics of heart mechanics, such as pressure volume relation, stroke volume and ejection fraction, can be generated by the present multi-scale cardiovascular model, covering from cardiac cells to circulation system.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
• /
• pp.551-554
• /
• 2002

As a general rule, the brazing process between cemented carbides and steel used by Silver (Ag) type brazing filler. The composition of Ag type filler were used Ag-Cu-Zn-Cd type filler mainly. But, the demand of Cadmium (Cd)-free in Ag type filler was raised recently. The reason why Cd-free in Ag brazing filler were occupied to vaporize as a CdO$_2$ when brazing process, because of Cd element was almost low boiling point of all Ag type filler elements. And, CdO$_2$ was a very harmful element for the human body. This experiment was developed Cd-freeing on Ag type filler that was used Indium (In) instead of Cd element. In this experiment, there were changed from 0 to 5% In addition in Ag brazing filler and investigated to most effective percentage of Indium. As a result, the change of In addition instead of Cd, there was a very useful element and obtained same property only 3% In added specimens compared to Cd 19% added specimens. These specimens were obtained same or more deflective strength. In this case, there were obtained 70 MPa over strength and wide brazing temperature range 650-800 C. A factor of deflective strength were influenced by composition and the shape of $\beta$ phase and between $\beta$ phase and cemented carbides interface. Indium element presented as $\alpha$ phase and non-effective factor directly, but it's occupied to solid solution hardening as a phase. $\beta$ phase were composed 84-94% Cu-Ni-Zn elements mainly. Especially, the presence of Ni element in interface was a very important factor. Influence of condensed Ni element in interface layer was increased the ductility and strength of brazing layer. Therefore, these 3% In added Ag type filler were caused to obtain a high brazing strength.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2009년도 추계학술발표대회
• /
• pp.39.1-39.1
• /
• 2009

NiTi alloy is widely used innumerous biomedical applications (orthodontics, cardiovascular, orthopaedics, etc.) for its distinctive thermomechanical and mechanical properties such as shape memory effect, super elasticity, low elastic modulus and high damping capacity. However, NiTi alloy is still a controversial biomaterial because of its high Ni content which can trigger the risk of allergy and adverse reactions when Ni ion releases into the human body. In order to improve the corrosion resistance of the TiNi alloy and suppress the release of Ni ions, many surface modification techniques have been employed in previous literature such as thermal oxidation, laser surface treatment, sol-gel method, anodic oxidation and electrochemical methods. In this paper, the NiTi was electrochemically etched in various electrolytes to modify surface. The microstructure, element distribution, phase composition and roughness of the surface were investigatedby scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry(EDS), X-ray diffractometry (XRD) and atomic force microscopy (AFM). Systematic controlling of nano and submicron surface features was achieved by altered density of hydro fluidic acid in etchant solution. Nanoscale surface topography, such as, pore density, pore width, pore height, surface roughness and surface tension were extensively analyzed as systematical variables.Importantly, bone forming cell, osteoblast adhesion was increased in high density of hydro fluidic treated surface structures, i.e., in greater nanoscale surface roughness and in high surface areas through increasing pore densities.All results delineate the importance of surface topography parameter (pores) inNiTi to increase the biocompatibility of NiTi in identical chemistry which is crucial factor for determining biomaterials.

• 한국가구학회지
• /
• 제18권2호
• /
• pp.91-99
• /
• 2007

Modernity which is superficial phenomenon set off the mass scale for mass consumption and provide uniformly artificial environment. But natural destruction, environment pollution, resources exhaustion and so on has been caused by this and now ecology is threatened by destruction and damage beyond the limitation and human beings survival is even threatened. Accordingly furniture development for environment preservation considered environment problem is the urgent real situation. Recent paradigm is the concept of Eco-design which is the green design possible to live together in symbiosis, and new types of alternative furniture are needed in Korea as well. 'Furniture for disassembly' is presented as new method for alternative furniture. Furniture for disassembly can be presented by mainly two directions. The first main characteristic is what is assembled by the use of woodworking joints technique as an assembly structure system without any hardware. The second is what is presented as the structure possible to be assembled by simple manual tools with hardware without any glue. The advantages of furniture for disassembly are environment preservation, space application, transportation efficiency and shapeliness. In manufacture method which is different from present furniture, the application of traditional truss technique which uses various types of custom-made and connection technique in case of assemble structure system without hardware is the typical differences. This assembly method expects not only interest induction about assembly and disassembly of diagram per sub materials but also the development of emotion, the improvement of collaboration, space perception ability and shape sense, the improvement of solid body structure insight and so on, when it use in the furniture for children with the application to many kinds of structure with BANGDOOSANJ (Wedged), JUMUGJANGBU (Dovetail) or NABIEUNJANG (Dovetail Keys) and so on.

• 한국방사선학회논문지
• /
• 제15권4호
• /
• pp.565-573
• /
• 2021

인체 내 전자기장의 공간 분포는 고 유전율 재료를 사용하여 비교적 간단하게 조정할 수 있다. 이 방법은 다른 방법에 비해 보완적인 성격이 강하지만 특정 응용 분야에서 강력한 유전체 시밍용 도구로 활용될 수 있다. 기하학적으로 자유로운 형상으로 제조 가능하며 시스템의 어떠한 변경 없이 목적에 따라 제작된 패드를 적용할 수 있다. 특히 초 고자장(ultrahigh magnetic field UHF) MRI에서 높은 작동 주파수로 인해 낮은 감도 (low sensitivity)를 갖는 송신 (B1+) 및 수신 (B1-) 필드의 강도를 높이는 데 사용되는 임상목적의 고 유전율 패드는 잠재적 가치가 상당히 클 뿐만 아니라 그 효과가 클 것으로 예상되는 UHF MRI에 적용된 연구가 적기 때문에 이 연구에서는 티탄산 칼슘의 현탁액으로 제조된 고 유전율 패드를 실험실에서 직접 개발하였으며 UHF 7T 자기공명영상 MRI의 다양한 프로토콜에서 임상적으로 유용한 영상의 신호증가를 확인하였다.

• 한국인터넷방송통신학회논문지
• /
• 제16권6호
• /
• pp.319-327
• /
• 2016

본 논문에서는 나무나 염소 뿔처럼 대부분의 동식물이 대칭임을 살펴본다. 또한 DNA를 가지고 있는 인간의 신체 역시 대칭이다. 피보나치수열, 식물의 나선, 동물의 대수 나선에서 볼 수 있는 것은 대칭이다. 해바라기 꽃은 원형이다. 원(元)은 원점을 중심으로 회전을 해도 모양이 꼭 같으므로 회전대칭이다. 공간상의 회전변환을 넘어서, 시간 공간의 대칭적 변환으로 일반화하면 아인슈타인의 특수상대성 이론이 시공간 변환관계이다. 동식물의 나선은 좌우 나선들이 대칭을 이루며 그 속에는 element-wise inverse가 존재한다. Hadamard 행렬 중 가운데 하중 값을 2로 준 것은 자연대수의 밑 2와 같고, 나선 행렬은 Symmetric하며 역행렬은 element-wise inverse이다.

• 한국의학물리학회:학술대회논문집
• /
• 한국의학물리학회 2002년도 Proceedings
• /
• pp.291-293
• /
• 2002

Accurate dose calculation in radiation treatment planning is most important for successful treatment. Since human body is composed of various materials and not an ideal shape, it is not easy to calculate the accurate effective dose in the patients. Many methods have been proposed to solve the inhomogeneity and surface contour problems. Monte Carlo simulations are regarded as the most accurate method, but it is not appropriate for routine planning because it takes so much time. Pencil beam kernel based convolution/superposition methods were also proposed to correct those effects. Nowadays, many commercial treatment planning systems, including Pinnacle and Helax-TMS, have adopted this algorithm as a dose calculation engine. The purpose of this study is to verify the accuracy of the dose calculated from pencil beam kernel based treatment planning system Helax-TMS comparing to Monte Carlo simulations and measurements especially in inhomogeneous region. Home-made inhomogeneous phantom, Helax-TMS ver. 6.0 and Monte Carlo code BEAMnrc and DOSXYZnrc were used in this study. Dose calculation results from TPS and Monte Carlo simulation were verified by measurements. In homogeneous media, the accuracy was acceptable but in inhomogeneous media, the errors were more significant.

• 감성과학
• /
• 제8권3호
• /
• pp.277-290
• /
• 2005

본 연구는 미래병사의 전투복 설계를 위한 기초 연구로 미래병사체계의 한 부분인 스마트 전투복의 디자인 프로토타입을 개발하는 것을 목적으로 한다 미래 전장은 정보의 습득과 전달이 승패의 핵심이 되는 정보전장이 될 것으로 생각되며, 미래병사를 위한 스마트 전투복은 전투력을 상승시키기 위한 각종 디지털 기기를 내장한 스마트 의류로서 전투복으로서 갖추어야 하는 착용성과 기기를 편안하게 사용할 수 있는 사용성을 모두 갖추어야 한다. 파라서 인체와 의복, 디지털 기기와의 관계를 연구하여 전투력을 상승시킬 수 있는 기기를 병사 특유의 동작에 방해되지 않도록 배치하기 위한 연구가 필요하다. 따라서 본 연구에서는 미래병사의 체형을 예측하고, 미래 병사에게 필요할 것으로 생각되는 각종 디지털 장치의 특성을 탐색하고, 동작과 인체의 구조를 연구하여 스마트 전투복의 최적 설계안이 도출되었다

• 한국환경농학회지
• /
• 제39권4호
• /
• pp.281-288
• /
• 2020

BACKGROUND: Generally, ammonia occurs from agricultural waste disposal. Ammonia is known as a harmful substance to the human body and has a bad influence such as eutrophication on the ecosystem. It is possible to remove the ammonia by ammonia adsorption method using natural zeolite, without external influence. However, due to the natural zeolite shape, it is hard to reuse. METHODS AND RESULTS: Electrospinning method can produce fiber with constant diameter. Moreover, electrospinning method has no limitation for selecting the material to make the fiber, and thus, it is valuable to reform the surface of adsorbent. In this study, reusable membrane was made by electrospinning method. The highest removal efficiency was shown from the membrane with 20% of zeolite included, and it has been verified that it is possible to reuse the membrane through chemical treatment. The highest ammonia removal efficiency was about 92.4%. CONCLUSION: In this study, ammonia adsorption characteristics of zeolite fibers were studied. Electrospinning method can produce zeolite fiber with even distribution. Ammonia can be removed efficiently from ion exchange ability of the natural zeolite. The result of adsorption isotherm indicated that both Freundlich model and Langmuir model provided the best fit for equilibrium data. And study on desorption has demonstrated that the ion exchange from zeolite was reversible when 0.01 M NaCl and KCl solution were used.

• 한국의류학회지
• /
• 제48권1호
• /
• pp.50-65
• /
• 2024

By analyzing the style of creator avatars in the world of Metaverse, which is emerging as a fourth-generation social media platform, this study aims to identify the meta-fashion tastes of Generation Z (Gen Z) creators (born in the late 2010s and early 2020s) and to analyze the extent to which current trends in the fashion market are influencing meta-fashion. The research method uses a case study to compare meta-fashion and current fashion trends. First, five Gen Z fashion creators on ZEPETO were selected to analyze the meta-fashion styles presented by this group. In the end, a total of 100 fashion styles were analyzed by combining 50 items each from the current meta-fashion and real fashion trends. The fashion styles were found to be hip-hop, easy-casual, punk, lovely feminine, and sexy, and the main fashion items were analyzed as jeans, hip-hop style pants, sneakers, tight crop tops, dresses, tattoos, chain accessories, and dyeing. Meta-fashion is the emergence of items similar in shape to those popular in the current fashion market, but are more exaggerated or show off the human body than actual fashion items.