• Archives of Plastic Surgery
• /
• 제49권2호
• /
• pp.266-274
• /
• 2022

Background Many authors have researched ways to optimize fat grafting by looking for a technique that offers safe and long-term fat survival rate. To date, there is no standardized protocol. We designed a "hydraulic system technique" optimizing the relationship among the quantity of injected fat, operative time, and material cost to establish fat volume cutoffs for a single procedure. Methods Thirty-six patients underwent fat grafting surgery and were organized into three groups according to material used: standard, "1-track," and "2-tracks" systems. The amount of harvested and grafted fat as well as material used for each procedure was collected. Operating times were recorded and statistical analysis was performed to establish the relationship with the amount of treated fat. Results In 15 cases the standard system was used (mean treated fat 72 [30-100] mL, mean cost 4.23 ± 0.27 euros), in 11 cases the "1-track" system (mean treated fat 183.3 [120-280] mL, mean cost 7.63 ± 0.6 euros), and in 10 cases the "2-tracks" one (mean treated fat 311[220-550] mL, mean cost 12.47 ± 1 euros). The mean time difference between the standard system and the "1-track" system is statistically significant starting from three fat syringes (90 mL) in 17.66 versus 6.87 minutes. The difference between the "1-track" system and "2-tracks" system becomes statistically significant from 240 mL of fat in 15 minutes ("1-track") versus 9.3 minutes for the "2-tracks" system. Conclusion Data analysis would indicate the use of the standard system, "1-track," and "2-tracks" to treat an amount of fat < 90 mL of fat, 90 ÷ 240 mL of fat, and ≥ 240 mL of fat, respectively.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
• /
• pp.389-396
• /
• 2002

In XXI century it is necessary to expect the recommencement and development of activities on mastering the Moon. In the long term it is construction of manned lunar bases with industrial, astrophysical, procuring, repair equipment and services. Interplanetary flights from the Moon demand smaller power expenditures, than from the Earth, therefore it is favourable to use its surface for the construction of space-vehicle launching sites. Flights of devices in libration points in the system 'Earth - Moon' are considered. Experience of engineering system creation for the Moon displays the great complexity in provision of serviceability and reliability of friction units. Open friction units should operate under following conditions on the Moon: pressure of environment (vacuum) $p\;>10\;^{-10}$ Pa; wide range of temperature change $+150^{\circ}C\;...170^{\circ}C$; high evaporability of lubricants; influence of temperature gradients and warping of constructions; sublimation of elements of constructional materials; irradiation of different physical nature; effect of micrometeorites; reduced gravitation; influence of abrasive particles of lunar ground; requirements on minimization of size and weight characteristics of a construction (high tension); undesirability (impossibility) of application of liquid and plastic lubricants; vibration, shock, acoustic loadings during start and landings to the Earth; difficulties in repair-regenerative operations in conditions of the Moon etc. Adhesive interaction of conjugated surfaces is the principal reason of possible failures of rubbed units on the Moon. In the research of the Moon automatic interplanetary stations of 'Luna' (USSR), 'Surveyer', 'Apollo' (USA) series were used. Stations executed functions of flying, landing, artificial satellites of the Moon, moon-rovers and manned spacecrafts such as 'Apollo'. The experimental- theoretical researches carried out in the sixtieth years on tribology for conditions of the Moon appeared to be rather useful to engineering of an outer space exploration and the decision of complex problems for the friction units operating in extreme conditions on the Earth. For the creation of highly loaded friction units for the long service life on the Moon it is required not only to use accumulated experience and designed technologies, but also to carry out wide scientific research.

• 대한기계학회논문집A
• /
• 제34권6호
• /
• pp.675-681
• /
• 2010

중간엽 줄기세포(MSCs)는 미분화 상태의 세포로써, 섬유아세포, 연골아세포, 골아세포 등으로 분화하여 인체의 근골격계를 구성하며, 기계적 자극은 중간엽 줄기세포 분화를 결정하는 중요한 인자로 알려져 이다. 본 연구에서는, 세포가 생존하기 위한 환경을 제공하고, 세포가 기계적 자극조건에 따라 분화할 수 있도록 하는 바이오리엑터를 제안하엿다. 또한, 중간엽 줄기세포를 배양하기 위한 세포 지지체로써 PU(polyurethane)로 제작된 지지체를 제안하였다. 세포 분화를 확인하기 위하여, 중간엽 줄기세포를 PU 지지체에 seeding한 후, 바이오리엑터를 이용하여 기계적 자극에 의한 세포의 분화를 확인하였다.

• Journal of Electrical Engineering and Technology
• /
• 제11권3호
• /
• pp.609-617
• /
• 2016

Belt-driven Starter Generator (BSG) differs from other mild hybrid systems as the crankshaft of vehicle are not run off. Motor permits a low-cost method of adding mild hybrid capabilities such as start-stop, power assist, and mild levels of regenerative braking. Wound rotor synchronous motor (WRSM) could be adopted in BSG system for HEV e-Assisted application instead of the interior permanent magnet synchronous motor (IPMSM). In practice, adequate torque is indispensable for starter assist system, and energy conversion should be taken into account for the HEV or EV as well. Particularly, flux weakening control is possible to realize by adjusting both direct axis components of current and field current in WRSM. Accordingly, this paper present an off-line current acquisition algorithm that can reasonably combine the stator and field current to acquire the maximum torque, meanwhile the energy conversion is taken into consideration by losses. Besides, on account of inductance influence by non-uniform air gap around rotor, nonlinear inductances and armature flux linkage against current variation are proposed to guarantee the results closer to reality. A computer-aided method for proposed algorithm are present and results are given in form of the Look-up table (LUT). The experiment shows the validity of algorithm.

• 전력전자학회논문지
• /
• 제14권1호
• /
• pp.62-71
• /
• 2009

본 논문에서는 마이크로 변위제어 시스템의 적층형 압전 액츄에이터를 위한 스위칭 증폭 구동회로의 구동방법을 제시하고 성능을 평가하였다. 이 증폭기는 압전 액츄에이터로부터 임의의 용량성 부하에 저장된 에너지를 효율적으로 회수할 수 있는 장점이 있다. 기존의 전압 되먹임 제어 방식은 100mHz의 정현파 기준치 추종시, 총 왜곡율이 -32dB (${\approx}2.5%$)로서, 액츄에이터의 전압과 변위 사이의 비선형적 관계로 인한 오차발생을 확인할 수 있었다. 이를 개선하기 위하여 전하 제어방식을 살펴보았는데, 기존의 직렬 커패시터를 연결하는 대신, 변위 기준치를 미분하고, 이를 출력전류와 비교하는 방식으로 개선하였다. 전하량 되먹임 제어 적용시 변위의 왜곡률은 약 -52dB (${\approx}0.25%$)로서 선형성이 매우 우수한 특성을 보임을 알 수 있다. 마지막으로 살펴본 직접 변위 제어 방식은 구현상의 복잡성으로 성능의 한계가 존재함을 알 수 있다.

• 한국산업융합학회 논문집
• /
• 제26권5호
• /
• pp.915-923
• /
• 2023

As environmental regulations on carbon emissions are strengthened worldwide, the existing internal combustion engine-centered automobile industry is being reformed. In particular, large buses and large cargo trucks are pointed out as one of the main causes of environmental destruction due to excessive carbon emissions. The E-Highway power collection system, which has recently been proposed as a solution, uses the vehicle's battery as a backup power source or regenerative braking, depending on whether the pan head of the pentograph installed in the vehicle is in contact with the overhead line. It is used to store the excess energy generated. However, wear through contact due to continuous contact reduces the current collection effect and causes failure. In this paper, by using the current difference, the horizontal position information of the panhead in contact with the overhead line is acquired, thereby reducing the abrasion of the conductor and the panhead Make it possible to follow the overhead line. The position estimation method proposed in this paper simply configures a device that can detect the position of the overhead line of the pantograph by the difference in resistance. It is economical and has the advantage of reducing the volume. The characteristics of the pantograph estimating the location of overhead lines were analyzed using the difference between the two currents of the current collector, the feasibility of the positioning estimation system was verified through simulations and experiments.

• 한국수소및신에너지학회논문집
• /
• 제25권6호
• /
• pp.648-655
• /
• 2014

This paper describes the continuing effort to develope a single acting free-piston Stirling engine/alternator combination for use of the household cogeneration. Free piston Stirling engines(FPSE) use variations of working gas pressure to drive mechanically unconstrained reciprocating elements. Stirling cycle free-piston engines are driven by the Stirling thermodynamic cycle which is characterized by an externally heated device containing working gas that is continuously re-used in a regenerative, reversible cycle. The ideal cycle is described by two isothermal process connected by two constant volume processes. Heat removed during the constant volume cooling process is internally transferred to the constant volume heating process by mutual use of a thermal storage medium called the regenerator. Since the ideal cycle is reversible, the ideal efficiency is that of Carnot. Free-piston Stirling engine is have no crank and rotating parts to generate lateral forces and require lubrication. The FPSE is typically comprised of two oscillating pistons contained in a common cylinder. The temperature difference across the displacer maintains the oscillations, and the FPSE operate at natural frequency of the mass-spring system. The power is generated from a linear alternator. The purpose of this paper is to describe the design process of the single acting free-piston Stirling engine/alternator. Electrical output of the single acting free-piston Stirling engine/alternator is about 0.95 kW.

• Restorative Dentistry and Endodontics
• /
• 제44권4호
• /
• pp.35.1-35.10
• /
• 2019

Pulp revascularization is an alternative treatment in immature traumatized teeth with necrotic pulp. However, this procedure has not been reported in horizontal root fractures. This is a case report of a 9-year-old patient with multiple horizontal root fractures in 2 upper central incisors that were successfully treated with pulp revascularization. The patient presented for treatment 2 years after the initial trauma, and revascularization was attempted after the initial treatment with calcium hydroxide had failed. Prior to pulp revascularization, cone-beam computed tomography and autoradiograms demonstrated multiple horizontal fractures in the middle and apical thirds of the roots of the 2 affected teeth. Revascularization was performed in both teeth; platelet-rich plasma (PRP) was used in one tooth (#11) and the conventional method (blood clot) was used in the other tooth (#21). Clinical and radiographic follow-up over 4 years demonstrated pulp calcification in the PRP-treated tooth. Neither of the 2 teeth were lost, and the root canal calcification of tooth #11 was greater than that of tooth #21. This case suggests that PRP-based pulp revascularization may be an alternative for horizontal root fractures.

• 한국정밀공학회지
• /
• 제26권3호
• /
• pp.25-31
• /
• 2009

Femto-second laser ablation with the various feed velocities of the Invar alloy and the micro surface milling for the processing condition were studied. We used a regenerative amplified Ti:sapphire laser with a 1kHz repetition rate, 184fs pulse duration time and 785nm wavelength. Femto-second laser pulse was irradiated on the Invar alloy with the air blowing at the condition of various laser peak powers and feed velocities. An ablation characteristic according to feed velocity of the Invar alloy was appeared as the non-linear type at different zone of energy fluence. The micro surface milling of the Invar alloy using a mapping method was investigated. The optimal condition of micro surface milling was laser peak power of 22.8mW, feed velocity of 1 mm/s, beam gap of $1{\mu}m$. With the optimal processing condition, the fine rectangular shape without burr and thermal damage was achieved. Using the femto-second laser system, it demonstrates excellent tool for micro surface milling of the Invar alloy without heat effects and poor edge.

• 대한한의학회지
• /
• 제25권2호
• /
• pp.138-150
• /
• 2004

Objectives : Alzheimer's disease (AD) is a geriatric dementia that is widespread in old age. In the near future AD will be the biggest problem in public health service. Although a variety of oriental prescriptions, including Sesim-tang, have been traditionally utilized for the treatment of AD, their pharmacological effects and action mechanisms have not yet been fully elucidated. The present study investigated the effects of Sesim-tang on apoptotic cell death induced by CT105 (carboxy terminal 105 amino acid peptide fragment of APP) overexpression in SK-N-SH neuroblastoma cell lines. Methods: We studied the regenerative and inhibitory effects on Alzheimer's disease in CT105-induced SK-N-SH cell lines by Sesim-tang water extract. We examined for cell morphological pattern, DNA fragmentation, LDH activity assay, zymography assay, and immunohistochemistric analysis. Additionally, we investigated the association between the CT105 and neurite degeneration caused by CT105-induced apoptotic response in neurone cells. Results: Findings from our experiments have shown that Sesim-tang inhibits the synthesis or activities of CT105, which has neurotoxicities and apoptotic activities in the cell line. In addition, pretreatment with Sesim-tang ($>50\mu\textrm{g}/ml$ for 12 hours) partially prevented CT105-induced cytotoxicity in SK-N-SH cell lines. SK-N-SH cell lines overexpressed with CT105 exhibited remarkable apoptotic cell damage. Based on morphological observations by phase-contrast microscope and LDH activity measurements in the culture media, the CT105-induced cell death was significantly inhibited by Sesim-tang water extract. Sesim-tang was found to reduce the expression of APP and caspase-3 induced by CT105 in SK-N-SH cell lines and in rat hippocampus. Conclusions: As the result of this study, in the Sesim-tang group, apoptosis in the nervous system is inhibited, the repair against the degeneration of SK-N-SH cell lines by CT105 expression is promoted. Hence, Sesim-tang may be beneficial for the treatment of AD.