• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.234-234
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• 2012

Saddle field ion source는 구조가 간단하고 영구자석을 사용하지 않아 소형화에 유리하고 구조가 간단한 DC 파워서플라이를 이용하기 때문에 장치 가격이 저렴하여 다양한 분야에서 응용되고 있으며 특히 이온빔 밀링 분야에 많이 사용된다. 초기 saddle field ion source 는 대칭형의 구형이었으나 지속적인 연구 개발로 와이어형, 원판형, 원통형 등 다양한 형태의 saddle field ion source가 개발되었다. 본 연구에서는 비교적 제작이 용이하고, 구조적으로 외부간섭에 대하여 덜 민감한 원통형 saddle field ion source를 제작하였다. 초기 saddle field ion source는 이온원 내부에 saddle field를 형성하기 위하여 대칭 구조를 가지 형태로 제작되었으나, 비대칭 구조에서도 saddle field가 형성될 수 있고 비대칭 구조를 채택할 경우 한쪽으로 더 많은 이온빔을 인출할 수 있기 때문에 실제 응용면에서는 비대칭 구조가 더 유리하다. 따라서 본 연구에서는 원통형 비대칭 saddle field ion source를 제작하였으며, 제작된 이온소스는 높이가 62 mm 지름이 55 mm의 소형 이온소스였다. 제작된 원통형 saddle field ion source는 진공도와 가속전압에 따라 방전 모드 변화하였다. Saddle field ion source는 전극과 extractor의 구조에 따라 조금씩 다르지만 대체로 5x10-5 Torr ~ 5x10-4 Torr 영역에서 안정적으로 작동하였다. 이온소스 내부의 압력이 높을 경우 수십 mA 의 방전 전류가 흐르는 고전류 방전 모드로 작동하였으며 압력이 낮을 경우에는 동일한 전압에서 수 mA 의 방전 전류만 흐르는 저전류 방전 모드로 작동하였다. 압력이 더 높아질 경우 아크 방전이 발생하여 이온소스의 작동이 불안정하여 연속적인 작동이 어려웠다. 고전류 방전 모드에서는 이온빔 전류가 Child-Langmuir 방정식에 따라 Vi3/2에 비례하여 증가하는 경향을 보여주었으며 저전류 방전 모드에서는 Vi에 선형적으로 증가하였다. 가속 전압이 동일한 경우 고전류 방전 모드가 저전류 방전 모드에 비하여 더 많은 이온빔 인출이 가능하지만, 고전류 방전 모드의 경우 이온의 방출 각도가 매우 넓은 반면 저전류 방전 모드에서는 이온빔의 퍼짐이 현저히 줄어듦을 관찰할 수 있었다. 원통형 saddle field ion source는 내부 구조가 간단하기 때문에 내부 전극의 구조 변화에 따라 방전 특성 및 이온빔 인출 특성이 심하게 변동하였다. Saddle field ion source에서는 Anode에 인가되는 방전 전압이 가속 전압과 같은 역할을 하는데 가속 전압은 2~10 kV 사이에서 인가가 가능하였다. 일반적으로 동일한 방전 모드에서 진공도가 높아질수록 방전 전류의 양과 인출되는 이온의 양이 증가하는 것이 관찰되었다. 제작된 이온소스는 최적 조건에서 5 mm 인출구를 통하여 0.7 mA의 이온빔 인출이 가능하였으며, 9 mm 인출구를 사용한 경우 1 mA까지 이온빔 인출이 가능하였다.

• Korean Journal of Applied Biomechanics
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• v.22 no.4
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• pp.413-419
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• 2012

The purpose of this study was to investigate the effects of increased saddle height on the length and activity pattern of vastus lateralis (VL) and biceps femoris (BF) muscle. To compare the effects of increased saddle height, Preferred (self-selected height of subject) and High saddle height (approximately 5% higher saddle height than self-selected) were used. Seven elite cyclists (career: $16.1{\pm}8.5years$) participated in 3 min. sub-maximal pedaling tests under the same cadence (90 RPM) and pedaling power (150 W). Hip and knee joint angles, and the length and activity of VL and BF were compared by measuring 3D motion and electromyography (EMG) data. Results showed that there were significant differences in peak extension timing of the hip joint angle and the range of motion of the hip and knee joint between different saddle heights. Although there were significant differences in muscle length of both muscles with increasing saddle height, the timing and amount of muscle activity differed only at the BF. These findings suggest that the timing and amount of bi-articular muscle activity (i.e. BF) can be altered by changing the saddle height. For practically applying these results, further study is necessary to evaluate the effects of various cadence and the pedaling power with various saddle heights.

• Journal of applied mathematics & informatics
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• v.29 no.5_6
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• pp.1167-1178
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• 2011

In this paper, we further investigate the local Hermitian and skew-Hermitian splitting (LHSS) iteration method and the modified LHSS (MLHSS) iteration method for solving generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. When A is non-symmetric positive definite, the convergence conditions are obtained, which generalize some results of Jiang and Cao [M.-Q. Jiang and Y. Cao, On local Hermitian and Skew-Hermitian splitting iteration methods for generalized saddle point problems, J. Comput. Appl. Math., 2009(231): 973-982] for the generalized saddle point problems to generalized nonsymmetric saddle point problems with nonzero (2,2) blocks. Numerical experiments show the effectiveness of the iterative methods.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.89-95
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• 2014

The increasing level of demand for multi-tasking machines requires a saddle with an ultra-precise machining accuracy level of $15{\mu}m$, as such a saddle is one of the main components of these machines. The manner of achieving ultra-precise machining accuracy mainly depends on the fixed forces. In this paper, we optimized the number of contact points and the contact positions to reduce the deformation of the saddle while it is machined. The performance levels of the proposed optimal jig and fixture are determined by measuring the flatness, parallelism and perpendicularity of a machined saddle. The machining accuracy is found to be lower than $15{\mu}m$ at all measured points.

• Korean Journal of Heritage: History & Science
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• v.35
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• pp.82-99
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• 2002

This is to study about the saddle rope from Cheonmachong Tomb in Gyeongju. Saddle rope was made by leather on 5-6th century in Korea, there was excavated in 1973 but reported yet. At that time the analysis was tried about burials, but this remains was omitted. In recent times this remains is confirmed newly. This is important thing to restruction of harness. The working methods of saddle rope is not simple, but complicated-double up, sewing and double fasten with precessed leather. The saddle rope is restructed with no-decorated and simple leather line to recent times. Now, restruction of ancient saddle rope must be used by this way.

• Bulletin of the Korean Mathematical Society
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• v.37 no.1
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• pp.11-19
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• 2000

We give a new coincidence theorem for multimaps on generalized convex spaces and apply it to deduce s-saddle point and saddle point theorems.

• Korean Journal of Applied Biomechanics
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• v.22 no.3
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• pp.357-363
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• 2012

The purpose of this study was to investigate the effects of different saddle heights on lower-limb joint angle and muscle activity. Six elite cyclists(age: $32.2{\pm}5.2years$, height: $171.0{\pm}3.5cm$, weight: $79.7{\pm}5.6kg$, cycle career: $13{\pm}6.2years$) participated in three min. submaximal(90 rpm) pedaling tests with the same load and cadence based on saddle heights where subject's saddle height was determined by his knee flexion angle when the pedal crank was at the 6 o'clock position. Joint angles(hip, knee, ankle joints) and the activity of lower limb muscles(biceps femoris(BF), vastus lateralis(VL), tibialis anterior(TA) and gastrocnemius medial(GM)) were compared by measuring 3D motion and electromyography(EMG) data. Results showed that there were significant differences in minimum hip & knee joint angle and range of motion of hip and knee joint between saddle heights. Onset timing and integrated EMG of only BF among 4 muscles were significantly different between saddle heights. Especially there was a negative relationship between minimum hip joint angle and onset timing of BF in most subject, which means that onset timing of BF became fast as the degree of bending of the hip joint became larger by saddle height. Optimal pedaling will be possible through increased amount of muscle activation due to the appropriate burst onset timing by proper pedaling posture with adjusted saddle height.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.9.1-9.9
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• 2016

Background: As dental implants receive masticatory stress, the distribution of stress is very important to peri-implant bone homeostasis and implant survival. In this report, we created a saddle-type implant and analyzed its stability and ability to distribute stress to the surrounding bone. Methods: The implants were designed as a saddle-type implant (SI) that wrapped around the alveolar bone, and the sizes of the saddles were 2.5, 3.5, 4.5, and 5.5 mm. The X and Y displacement were compared to clarify the effects of the saddle structures. The control group consisted of dental implants without the saddle design (CI). Using finite element modeling (FEM), the stress distribution around the dental implants was analyzed. Results: With saddle-type implants, saddles longer than 4.5 mm were more effective for stress distribution than CI. Regarding lateral displacement, a SI of 2.5 mm was effective for stress distribution compared to lateral displacement. ASI that was 5.6 mm in length was more effective for stress distribution than a CI that was 10 mm in length. Conclusions: The saddle-type implant could have a bone-gaining effect. Because it has stress-distributing effects, it might protect the newly formed bone under the implant.

• Archives of Plastic Surgery
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• v.34 no.1
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• pp.81-87
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• 2007

Purpose: Correction of saddle nose remains problematic both in the technique of reconstruction and in the choice of implant material for nasal augmentation. A large variety of graft materials have been used for the reconstruction of the saddle nose deformity. The purpose of this study is to determinate an algorithm for deciding alternative graft materials used in correction of saddle nose deformity. Methods: Six patients with saddle nose who were corrected using by auricular cartilage and costal cartilage at Chosun university hospital were analyzed. Results: After a mean interval of 12 months, all patients were satisfied with the esthetic and functional result. Conclusion: Auricular cartilage is an excellent graft material for esthetic and functional reconstruction of mild to moderate saddle nose deformity.

• Bulletin of the Korean Chemical Society
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• v.7 no.5
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• pp.376-379
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• 1986

A relatively simple method of locating the saddle point is presented. In this method a single determination of the saddle point location by constrained energy minimizations for points selected on the assumed saddle surface provides us with the structure, location and energy of the TS, the reaction path at the saddle point and characterization as the TS. Some examples were given.