교정용 브라켓과 강선 사이의 운동마찰저항력에 관한 실험적 연구

이재환,이기수 대한치과교정학회 2001 대한치과교정학회지 Vol.31 No.4

이 연구의 목적은 호선으로 유도되는 치아이동을 실험실에서 실현하는 동안 브라켓과 선재의 운동 마찰저항에 대한 브라켓 수, 브라켓 폭경, 선재 크기가 미치는 영향을 관찰하기 위한 것이다 상악 제 1, 2 소구치, 제 1 대구치와 유사한 크기의 레진 치아를 사용하였으며, 치주인대와 탄성계수가 비슷한 폴리 에테르 인상재를 사용하였다. 스테인레스 스틸 트윈 에지와이즈 브라켓으로 좁은 폭경 (2.4 mm), 중간 폭경 (3.0 mm), 넓은 폭경 (4.3 mm)을 사용하 였으며, 강선으로는 0.016, 0.018, 0.016 × 0.022, 0.019 × 0.025인치의 굵기를 사용하였고, 결찰은 합성고무링을 이용하고, 제1소구치에 부착된 좁은 폭경 브라켓 1개, 제 1, 2소구치에 부착된 2개의 중간 폭경 브라켓 및 제 1, 2소구치와 제 1 대구치에 부착된 3개의 중간 폭경 브라켓과 각 강선 사이의 운동 마찰저항력을 계측하여 다음의 결론을 얻었다. 1.좁은 폭경, 중간 폭경, 넓은 폭경 세 종류의 브라켓 모두에서 교정용 선재의 단면 크기가 증가할수록 마찰저항력도 증가하였다. 2. 0.016, 0.018인치 원형 강선은 브라켓 폭경이 증가하면 운동마찰저항력은 감소하며, 0.016 × 0.022, 0.019 × 0.025인치 각형 강선은 브라켓 폭경이 증가하면 운동마찰저항력이 증가하는 경향이 있었고 0.016인치 원형 강선과 폭경이 다른 브라켓과의 운동마찰저항력 사이에는 통계적으로 유의차가 없었다. 3.중간 폭경 브라켓의 수가 증가할수록 마찰저항력은 크게 나타났으며, 그 증가율은 브라켓의 수에 비례하였으나 정수배로 증가하지는 않았고 강선의 굵기에 따라 차이가 있었다. (주요 단어 : 운동마찰저항, 교정용 브라켓수, 브라켓 폭경, 교정용 선재) This investigation was designed to determine the effects of wire size, bracket width and the number of bracket on bracket-wire dynamic frictional resistance during simulating arch wire-guided tooth movement in vitro. For simulation of an arch wire-guided tooth movement, we simulated tooth, periodontal ligament and cancellous bone. Maxillary premolar and 1st molar were simulated as real sized resin teeth, the simulated resin teeth which its root was coated by polyether impression material which its elastic modulus is similar to periodontal ligament were embedded in steel housing with inlay wax which its elastic modulus is similar to cancellous bone. Stainless steel wires in four wire size (0.016, 0.018, 0.016 × 0.022, 0.019 × 0.023 inch) were examined with respect to three (stainless steel) bracket widths (2.4, 3.0, 4.3mm) and the number of medium bracket(one, two, three) included in the experimental assembly under dry condition. The wires were ligated into the brackets with elastomeric module. The results were as follows : 1.In all the brackets, frictional resistance increased with increase in wire size. But, statistically similar levels of frictional resistance were observed between 0.018 inch and 0.016 × 0.022 inch wires in narrow bracket and also between 0.016 inch and 0.018 inch wire in wide backet. 2.The frictional forces produced by 0.016 inch wire were statistically similar levels in all the brackets. In 0.018 inch round wire, wide bracket was associated with lower amounts of friction than both narrow and medium brackets. In 0.016 × 0.022, 0.019 × 0.025 inch rectangular wire, wide bracket produced larger friction than both narrow and medium brackets. In all the wires, narrow and medium bracket demonstrated no statistical difference in levels of frictional resistance. 3.Frictional resistance increased with increase in number of medium bracket. 0.016 inch round wire demonstrated the greatest increment in frictional resistance, followed by 0.019 × 0.025, 0.016 × 0.022 inch rectangulal wire which were similar level in increment of frictional resistance, 0.018 inch wire demonstrated the least increment. The increments of frictional resistance were not constantly direct proportion to number of bracket. ※ Key words : Dynamic frictional resistance, Number of orthodontic bracket. Bracket width. Orthodontic wire

Innovation Resistance Model of Sustainable SCM: Mediating Effect on Dynamic Capability

이다솔 한국무역학회 2023 Journal of Korea trade Vol.27 No.3

Purpose – Although the importance and necessity of “sustainable supply chain management (SCM)” is emphasized, it is often not realized due to conflicting results, the long time required, and large-scale changes brought about by sustainability. This study used the innovation resistance model to confirm the influence of sustainable SCM innovation resistance factors and dynamic capabilities on adoption intentions. This approach made it possible to understand the factors that hinder adoption of sustainability practices and to identify the relationships among influencing factors. It should also help to establish effective policies or strategies. Design/methodology – Through a literature review, the characteristics of sustainable SCM were classified into relative advantage, compatibility, perceived risk, and complexity. The effects of these innovation characteristics on innovation resistance in sustainable SCM and the effects of innovation resistance on adoption intentions were confirmed. In addition, the effects of SCM capabilities on innovation resistance and adoption intentions were analyzed, and the mediating effect of innovation resistance was analyzed. Findings – Compatibility, perceived risk, and flexibility had significant effects on innovation resistance. In turn, innovation resistance had a significant effect on adoption intention, and flexibility had a significant effect on intention to adopt. A partial mediating effect of resistance to innovation was confirmed. Originality/value – Although many previous studies have acknowledged trade-offs with sustainability, most sustainable SCM studies dealt with the correlations among positive drivers of adoption, practices, and performance. This study confirmed the process of accepting sustainable SCM innovation in a single model and is expected to serve as a cornerstone for future sustainable SCM adoption studies. In addition, our findings should help establish effective policies or strategies to activate SSCM adoption by identifying the factors that hinder the adoption of sustainable SCM.

Dynamic on resistance measurement of high power GaN under hard/passive switching

Huizhong Sun,Zhihao Lin,Jing Yuan,Huai Wang 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-

It’s well recognized that the Rdson of GaN HEMT changes much under different operating conditions. To precisely calculate the GaN HEMT switch loss, it’s necessary to measure the resistance. Otherwise, significant loss error might be obtained, especially high-frequency soft switching. In the past several years, many research and experiments are implemented to explain/test/model this phenomenon. However, no systematic measurement results/setups are reported for the 650V GaN device. This paper aims to make a systematic resistance measurement based on high-power 650 V GaN HEMT, including the on resistance with different temperature/current/frequency/duty/switching statuses. The measurement results show frequency/temperature/switching status are the main factors of dynamic on resistance. While the current/duty is less effective on dynamic on resistance. Polynomial fitting results are accurate enough to predict the dynamic on resistance. With the testing results reported in this paper, the readers could predict the switching loss of GS66516T with much better accuracy.

외부 교류자장이 Bi-2223테이프의 동저항 및 손실특성에 미치는 영향

류경우,최병주,Ryu, Kyung-Woo,Choi, Byoung-Ju 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.5

A Bi-2223 tape has been developed for power applications such as a fault current limiter, a power cable and a superconducting magnetic energy storage system. In such applications, the Bi-2223 tape carries time varying transport current and in addition experiences time varying external magnetic field. It is well known that the external magnetic field not only causes magnetization loss in the Bi-2223 tape, but also drastically increases transport loss due to a so-called 'dynamic resistance' We developed an evaluation setup, which can measure transport loss in external at magnetic fields. Using this equipment, we measured the dynamic resistances for various amplitudes and frequencies of an external at magnetic field perpendicular to the face in the tape. Simultaneously we investigated the effect of an external ac field on transport loss with different experimental conditions. This paper describes test results ana discussions on correlation between the dynamic resistance and the transport loss for the Bi-2223 tape.

A comparison study on the deck house shape of high speed planing crafts for air resistance reduction

박충환,박희승,장호윤,임남균 대한조선학회 2014 International Journal of Naval Architecture and Oc Vol.6 No.4

Planing crafts were specifically designed to achieve relatively high speeds on the water. When a planingcraft is running at high speed, dynamic pressure on the bottom makes the boat rise on the surface of the water. Thisreduces the area of the sinking surface of the boat to increase air resistance. Air resistance means the resistance thatoccurs when the hull and deck house over the surface of the water come in contact with the air current. In this paper, wecarried out a CFD numerical analysis to find optimal deck houses that decreased air-resistance on the water whenplaning crafts are running at high speed. We finally developed the deck house shape of high-speed planing crafts thatoptimally decreased air resistance.

A comparison study on the deck house shape of high speed planing crafts for air resistance reduction

Park, Chung-Hwan,Park, Hee-Seung,Jang, Ho-Yun,Im, Namkyun The Society of Naval Architects of Korea 2014 International Journal of Naval Architecture and Oc Vol.6 No.4

Planing crafts were specifically designed to achieve relatively high speeds on the water. When a planing craft is running at high speed, dynamic pressure on the bottom makes the boat rise on the surface of the water. This reduces the area of the sinking surface of the boat to increase air resistance. Air resistance means the resistance that occurs when the hull and deck house over the surface of the water come in contact with the air current. In this paper, we carried out a CFD numerical analysis to find optimal deck houses that decreased air-resistance on the water when planing crafts are running at high speed. We finally developed the deck house shape of high-speed planing crafts that optimally decreased air resistance.

Effect of wave periods on added resistance and motions of a ship in head sea simulations

Seo, Seonguk,Park, Sunho,Koo, BonYong Elsevier 2017 Ocean engineering Vol.137 No.-

<P><B>Abstract</B></P> <P>Given that the International Maritime Organization (IMO) recently introduced the Energy Efficiency Design Index (EEDI) for new ships and the Energy Efficiency Operational Indicator (EEOI) for ship operations, accurate prediction of the added resistance of ships advancing in waves has become necessary. In the present study, the open-source computational fluid dynamics library, OpenFOAM, was used to predict the added resistance with the motions of a ship. Unstructured grid using a hanging-node and cut-cell method was used to generate fine grid around a free-surface and ship. Five wavelengths from a short wavelength (<I>λ/L</I> <SUB> <I>PP</I> </SUB>=0.65) to a long wavelength (<I>λ/L</I> <SUB> <I>PP</I> </SUB>=1.95) were considered as head waves. The grid uncertainty was evaluated with respect to three grid systems for a wavelength of <I>λ/L</I> <SUB> <I>PP</I> </SUB>=1.15. The predicted added resistance and heave and pitch motions with various head waves were compared with the data from model experiments. The wave pattern around the ship and the motions of the ship were analyzed with respect to the wave encounter period. When the wavelength was similar to the ship length, the ship moved against the waves, and thus the added resistance was greater compared with other wavelengths.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Added resistance is small in waves with short and long wavelengths. </LI> <LI> When wavelength is similar to ship length, ship moves against waves. </LI> <LI> Long wavelength makes to easier prediction of added resistance. </LI> <LI> Vortices structures around stern by ship motions are presented. </LI> </UL> </P>

Interface Thermal Resistance between Liquid Water and Various Metallic Surfaces

Truong Quoc Vo,김보흥 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

Enhancing thermal transport mechanisms in nanostructures and nanomaterials are important factors for their use in green renewable energy applications. The behaviors and reliability of nanoscale devices strongly depend on the way the systems dissipate heat. Therefore, using non-equilibrium molecular dynamics (MD) simulations, we investigated the interface thermal resistance between liquid water and various metallic surfaces in nanochannels. Solid-liquid interface thermal resistance is well known as the Kapitza length. In this study, we model heat transfer through two parallel solid walls separated by liquid water, holding each solid wall at a different temperature to impose a temperature gradient. Silicon with a diamond crystal lattice structure and copper, silver, gold, and platinum with face-centered cubic (FCC) crystal lattice structure were chosen as the solid materials due to their extensive applications in nanotechnology. Temperature jumps at such solid-liquid interfaces are due to thermal transport between the dissimilar materials, resulting in an interface thermal resistance. We observed the behaviors of liquid water molecules in the vicinity of the metallic surfaces, revealing that the Kapitza length varies as a function of solid-liquid interaction strength, and confirming the effect of Lennard-Jones (LJ) interaction added to long-range Coulombic interaction in the liquid model, and using liquid water instead of simple LJ liquid.

제주에 대한 재현의 폭력과 저항의 역학관계

이도흠 ( Do Heum Lee ) 한국기호학회 2012 기호학연구 Vol.32 No.-

There were three kinds of the vilolence of representation for peoples of Jeju island: the remotest place of exile, island of a red, a beautiful island of sightseeing without history. I applied the theory of dependent origination to the dynamic relation of violence. Since others is penetrating inside me and I am also penetrating inside others, separating me and others is just a delusion. Therefore, a human being is intrinsically ``inter-becoming``. A violence is doing between the strong and the weak, between a strain and a strength dynamically. There is a resistance where the violence is doing. The confucian power elite in Choseon dynasty represented Jeju island as the remotest place of exile. Practically, they had forbidden every peoples in Jeju Island to enter inland, and had exiled the man who the king hate extremely to this island. The discourses that Jeju island is a land of God and Goddess stood against the discourses of exile. However, the latter had the superiority over the former in the struggle of hegemony overwhelmingly. The ruling class in modernized Korea represented Jeju island as the land of reds for the purpose of covering up a truth of Jeju 4.3 resistance. They had massacred scores of thousands of the residents in Jeju island during Jeju 4.3 resistance. They had forbidden every peoples not only the residents in Jeju Island but also all Korean to express a word about Jeju 4.3 resistance. After democratization movement against military dictatorship, the discourses that Jeju 4.3 resistance is a massacre of the innocent people by government power stood up to the discourse of reds. Owed to the fall of military dictatorship by democratization movement, the former had the superiority over the latter in the struggle of hegemony. The capital, government, and the press represented Jeju island as a beautiful island of sightseeing without history. They erased history of Jeju island in the memory of Korean. They regarded Jeju island as the object of sightseeing. They are developing and exploiting people and resources in Jeju island. The discourses that described Jeju island as the field of history faced against the discourse of the land of sightseeing. However, because the latter is created and communicated by the capital and the press unlimitedly, so the former is inferior to the latter in the struggle of hegemony.

전산유체역학을 이용한 수중운동체 저항해석 및 예인수조에서의 저항시험 방법에 대한 고찰

박정훈(Jeonghoon Park),김성훈(Sunghoon Kim),정배균(Baegyun Jeong),김종순(Jongsoon Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

Flow Resistance is very important element in flight performance of underwater vehicle. Generally, We used the method of towing model in constant velocity and measuring force to obtain the resistance. However, resistance in real flight velocity of vehicle is calculated by applying theoretical prediction of surface vehicle resistance test, because of performance limit of towing tank(for example, towing velocity Etc.). In this paper, we calculated resistance of underwater vehicle by using CFD(Computational Fluid Dynamics), and checked the reliability of simulation model, comparing to experiment results. In addition, resistance simulation results by applying towing tank method were compared to those by applying real flight velocity, and we verified feasibility of prediction in towing tank test.