• 반도체디스플레이기술학회지
• /
• 제19권4호
• /
• pp.18-21
• /
• 2020

Undetected wafer slip during the lift pin-down motion in semiconductor equipment may affect the center to edge variation, wafer warpage, and pattern misalignment in plasma equipment. Direct measuring of the amount of wafer slip inside the plasma process chamber is not feasible because of the hardware space limitation inside the plasma chamber. In this paper, we demonstrated a practice for the wafer lift pin-up and down motions with respect to the gear ratio, operating voltage, and pulse width modulation to maintain accurate wafer position using remote control linear servo motor with an experimentally designed chamber mockup. We noticed that the pin moving velocity and gear ratio are the most influencing parameters to be control, and the step-wised position control algorithm showed the most suitable for the reduction of wafer slip.

• 전력전자학회논문지
• /
• 제27권5호
• /
• pp.446-454
• /
• 2022

This study proposes a carrier-based pulse width modulation (PWM) method for leakage current reduction and neutral point (NP) current control in a three-phase three-level converter, which is a carrier-based PWM version of the previously proposed low-frequency common mode voltage PWM. Three groups of space vectors with the same common mode voltage are used. When the averaged NP current needs to be positive or negative, the specific groups are employed to produce low-frequency common mode voltages. The validity of the proposed PWM method is verified through experiments.

• 한국방재학회 논문집
• /
• 제10권2호
• /
• pp.123-133
• /
• 2010

강변저류지와 같은 소규모 수공구조물에 의한 홍수저감방안의 필요성이 증가하고 있으며, 대상 유역내에 다수의 후보지역이 존재하는 강변저류지 계획에 있어서, 네트워크로 간주된 전체 저류지군의 실질적인 홍수조절효과의 산정이 필수적이다. 본 연구에서는 저류용량, 월류고, 월류폭 등과 같은 강변저류지 제원에 대한 민감도 분석을 통한 강변저류지군의 홍수저감효과 개선기법을 제안하였다. 제안된 기법은 설계빈도 홍수사상에 대하여 강변저류지 제원 변화에 따른 직하류부 및 유역출구 홍수저감량 민감도 분석을 실시하고, 민감도분석 결과를 이용하여 직하류부와 유역출구에서의 홍수저감량이 최대가 되게 하는 강변저류지 제원을 결정한다. 제안된 기법을 안성천 유역에 적용하여 적용성을 검토하였으며, 기존의 연구결과와 본 연구에서 제안한 기법의 결과를 비교분석하였다.

• Archives of Plastic Surgery
• /
• 제50권1호
• /
• pp.17-25
• /
• 2023

A variety of reduction labiaplasty techniques have been introduced to date, but no single technique will offer the optimal solution for every patient. Rather, the technique should be chosen based on anatomical, configurational, and technical considerations, as well as on patients' personal preferences regarded maintenance of the labial rim, maintenance of labial sensitivity, and prevention of iatrogenic thickening of the labium. We reviewed, defined, and assessed labial configurational variety, neurovascular supply, reduction techniques, and patient's preferences as the considerations relevant to the choice of labiaplasty technique. Based on this review, an algorithm was constructed that leads to a choice of reduction technique through five decisions to be made regarding (1) resection or (partial) retention of the labial free rim, (2) the measure of required labial width reduction, (3) labial vascular status, (4) prevention of iatrogenic labial thickening, and (5) preservation of labial sensibility. The choice of techniques includes edge trimming, central spindle form de-epithelialization or full-thickness resection, and three modifications of the wedge resection or de-epithelialization technique. These three modifications comprised a modified anterior resection or de-epithelialization combined with posterior flap transposition, a custom flask resection or de-epithelialization, and a modified posterior wedge resection or de-epithelialization combined with anterior flap transposition. Use of the five decisional steps and the inclusion of modifications of all three conventional reduction techniques offer an improved algorithm for the choice of labioplasty technique.

• Journal of Chest Surgery
• /
• 제47권4호
• /
• pp.358-366
• /
• 2014

Background: To improve sinus rhythm conversion, the Cox maze III procedure with narrow mazes (width: ${\leq}3.0cm$) was performed in combination with left atrial volume reduction. Methods: From October 2007 to April 2013, 87 patients with atrial fibrillation (paroxysmal in 3, persistent in 14, and permanent in 70) underwent the Cox maze procedure concomitant with another cardiac procedure. They were followed-up with serial electrocardiographic and echocardiographic studies. We used 24-hour Holter monitoring tests to evaluate postoperatively symptomatic patients. Results: At the mean follow-up time of 36.4 months, 81 patients (94.2%) had sinus rhythm and two were on anti-arrhythmic medication (one on a beta-blocker and the other on amiodarone). Five patients (5.8%) with postoperative recurrent and persistent atrial fibrillation never experienced sinus rhythm conversion; however, they did not require any medication for rate control. On postoperative echocardiography, the left atrial A waves were more frequently observed after concomitant mitral valve repair than after concomitant mitral valve replacement (82.4% vs. 40.4%, respectively; p<0.001). Conclusion: For the Cox maze procedure, narrow mazes and atrial volume reduction resulted in excellent sinus rhythm conversion without the preventive use of anti-arrhythmic drugs, and they did not affect the presence of the left atrial A waves on echocardiography.

• Computers and Concrete
• /
• 제21권2호
• /
• pp.117-126
• /
• 2018

This research investigate the behavior of reinforced normal and lightweight aggregate concrete hollow core slabs with different core shapes, shear span to effective depth (a/d). The experimental work includes testing seven reinforced concrete slabs under two vertical line loads. The dimensions of slab specimens were (1.1 m) length, (0.6 m) width and (0.12 m) thickness. The maximum reduction in weight due to aggregate type was (19.28%) and due to cross section (square and circular) cores was (17.37 and 13.64%) respectively. The test results showed that the decrease of shear span to effective depth ratio from 2.9 to 1.9 for lightweight aggregate solid slab cause an increase in ultimate load by (29.06%) and increase in the deflection value at ultimate load or the ultimate deflection by (17.79%). The use of lightweight aggregate concrete in casting solid slabs give a reduction in weight by (19.28%) and in the first cracking and ultimate loads by (16.37%) and (5%) respectively for constant (a/d=2.9).The use of lightweight aggregate concrete in casting hollow circular core slabs with constant (a/d=2.9) (reduction in weight 32.92%) decrease the cracking and ultimate loads by (12%) and (5.18%) respectively with respect to the solid slab. These slab specimens were analyzed numerically by using the finite element computer program ANSYS. Good agreements in terms of behavior, cracking load (load at first visible crack) and ultimate load (maximum value of testing load) was obtained between finite element analysis and experimental test results.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 1999년도 추계학술발표대회 논문집
• /
• pp.68-72
• /
• 1999

In an effort to construct a structure under the design principle of minimal use of materials for maximum performances, a discrete gradient structure has been introduced in laminate composite systems. Using a sequential linear programming method, the gradient structure of composites to maximize the buckling load was optimized in terms of fiber volume fraction and thickness of each layer. Theoretical optimization results were then verified with experimental ones. The buckling load of laminate composite showed maximum value with the outmost [$0^{\circ}$] layer concentrated by almost all the fibers when the ratio of length to width(aspect ratio) was less than 1.0. But when the aspect ratio was 2.0, the optimum was determined in a structure where the thickness and fiber volume fraction were well balanced in each layer. From the optimization of gradient structure, the optimal fiber volume fraction and thickness of each layer were proposed. Experimental results agreed well with the theoretical ones. Gradient structures have also shown an advantage in the weight reduction of composites compared with the conventional homogeneous structures.

• 한국전자파학회논문지
• /
• 제25권7호
• /
• pp.767-773
• /
• 2014

본 논문에서는 무한 도체 평판의 슬릿 부근에 도체판을 부가하여 슬릿으로 침투하는 전자파의 저감 특성을 검토하였다. 이론 해석에는 FDTD 법을 사용하였으며, 부가 도체판의 형상 및 길이, 간격, 두께의 변화에 따른 침투 전계의 특성을 계산하여 부가 도체판의 구조 변화가 침투 전자파의 저감 특성 및 차폐 효과 특성에 미치는 영향을 고찰하였다. 그 결과, 부가 도체판의 구조 변화에 따라 차폐 효과, 침투 전계의 특성이 변화하는 것을 관찰할 수 있었고, 침투 전계를 최소로 하는 부가 도체판의 최적 구조가 있음을 확인할 수 있었다.

• 한국분말재료학회지
• /
• 제9권1호
• /
• pp.25-31
• /
• 2002

The efects of mechanical aloying conditions and the type of reducing agent on the solid state reductionof haematite $Fe_2O_3$ have been investigated at room temperature. Aluminium titanium zinc and copper were used as reducing agent. Nanocomposites of metal-oxide in which oxide particles with nano size were dispersed in Fe matrix were obtained by mechanical alloying of $Fe_2O_3$ with aluminium and titanium respectively However the reduction of $Fe_2O_3$ by coppe was not occurred Composite materials of iron with $Al_2O_3$ and $TiO_2$ were obtained from the system of $Fe_2O_3-Al$ and $Fe_2O_3-Ti$ after ball milling for 20 hrs and 30 hrs respectively. And the system of $Fe_2O_3-Zn$ resulted in the formationof FeO with ZnO after ball milling of 120 hrs. The final grain sizes of iron estimated by X-ray diffraction line-width measurement were in the ranges of 24~33 nm.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2009년도 춘계학술대회 논문집
• /
• pp.114-117
• /
• 2009

In this work, closing behavior of the voids generated in a casting process was investigated for various parameters such as reductions in height void size and billet rotation during hot open die forging process. The reduction in height and path schedule including the number of paths and billet rotation were chosen as key process variables to express the change of geometrical void shape and void closing behavior. On the other hand, values of die overlapping and die width ratio were set to be constant. Extend of void closure was observed and evaluated using tensile test and microscope. Based on the experimental result, it is ensured that void closure do not occur at 15% and 30% reduction in height as well as one or two rotations of a billet. The useful datum obtained from this study could be utilized to establish an optimum path schedule in the open die forging process.