• 전기학회논문지
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• 제60권7호
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• pp.1385-1390
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• 2011

A coaxial-conical-radial transmission line conversion circuits have been investigated to realize a low loss high performance microwave power divider/combiner. In order to optimize the characteristics of the device, the power divider/combiner was designed separately with two parts-the inner part and the outer part. Utilizing the rectangular approximation of the outer part, we can design the low loss device which is not affected by the partition number N of the outer part. The small return loss which is lower than 20dB was obtained on the frequency range of 5.15GHz(7.45~12.60GHz). A conical connector was employed for smooth connection between the central coaxial line and the outer radial line. Making use of the $47^{\circ}$ and $90^{\circ}$ 2-stage conical connector, the return loss lower than 30dB was obtained on the operating frequency range of 5GHz. The total return loss of the designed divider/combiner was lower than 20dB on the frequency range of 5GHz for the partition number N=11, N=12 and N=16.

• 대한한의학회지
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• 제44권1호
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• pp.56-64
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• 2023

Objectives & Methods: The entire ≪Lingshu·Jingjin≫ content was analyzed to find repetitive patterns, as well as to analyze commonly used terms. Through this, the guidelines for interpretation were presented. Results & Conclusions: ≪Lingshu·Jingjin≫ is not a question-and-answer format, but a simple enumerated narrative format. There is no part corresponding to the introduction, only the descriptions of 12 individual Meridian-muscle exist. Each Meridian-muscle is divided into 'Flow of Muscle Mechanics(流走)' part and 'Diseases' part, and 'Flow of Muscle Mechanics' of each Meridian-muscle can be divided into 'Main Flow' and 'Branch'. 'Main Flow' is the most central 'Flow' in each 'Meridian-muscle', and 'Branch' is the part where 'Main Flow' ends and the description of another 'Flow' begins. 'Branch' has different expressions according to the importance. The expression also varies depending on the dynamics. 'Meridian-muscle' should be interpreted based on this.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.182-188
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• 1999

A theoretical study of elastohydrodynamic lubrication of elliptical contacts with both rolling and spin has been carried out. A finite difference method and the Newton-Raphson method are applied to solve the problem. The velocity vectors resulting from combined spin and rolling/sliding motion lead to asymmetric pressure distributions and film shapes. Film contours and variations of the minimum and central film thicknesses are compared with various spin-roll ratios. At high spin-roll ratios the minimum film thickness is considerably reduced, whereas the central film thickness decreases less dramatically, The present numerical scheme can be used in the analysis of general elliptical contact problems.

• 천문학회보
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• 제40권1호
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• pp.78.2-78.2
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• 2015

Powered by a supermassive black hole, active galactic nuclei (AGNs) are characterized by prominent emission lines including Blamer lines. The unification scheme of AGNs requires the existence of a thick molecular torus that may hide the broad emission line region. In this configuration, it is expected that the far UV radiation from the central engine can be Raman scattered by neutral hydrogen to reappear around Balmer lines which can be identified observationally with broad Balmer wings. Another mechanism that can form Balmer wings is considered by invoking a fast moving medium around the central engine. In this presentation, we produce Balmer wings that are formed through Raman scattering and also those expected from a fast moving emission flow. It is noted that Raman Balmer wings exhibit stronger red part whereas the opposite behavior is seen in the Balmer wings obtained from a fast moving emission flow.

• 천문학회지
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• 제17권1호
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• pp.23-36
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• 1984

From the PDS scanning, isophote maps and surface luminosity distributions for the late type spiral galaxy NGC 6946 were obtained. Surface luminosity distribution showed that this galaxy can be classified as the Freeman's type II, and the deep spheroidal component was caused as a result of the ring structure in the central part of NGC 6946. Physical parameters-total magnitude ($M_T^B$), effective radius ($R_e^*$), central surface magnitude $U(0)_{CD}$, length scale (${\alpha}^{-1}$), disk-to-bulge ratio (D/B) and mass-to-luminosity ratio (M/L)-were also calculated, and the results show that NGC 6946 belongs to Sc I type galaxy according to the DDO classification, and is to be a fair sample of classification statge T=6.

• 대한화학회지
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• 제4권1호
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• pp.13-14
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• 1957

Th-determination by the sebacic acid method was compared with the hydrogen peroxide method. The former is a little more complicated than the latter in the operation and at the same time it requires careful pH adjustment, but the time needed for determination could be decreased greatly by the former. As a result of the comparison between both methods we confirmed that, within ${\pm}$0.08 ${\%}$ of error, when $ThO_2$ was contained $5{\%}$ in the sample, we could use the sebacic acid method with an half time of that required for the hydrogen peroxide method. Thorium in Monazite sand was also determined by both methods and compared. In the case we found, too, that if we permitted the maximum error of ${\pm}$0.08 ${\%}$, we could prefer the sebacic acid method.

• 대한기계학회논문집A
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• 제27권3호
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• pp.450-454
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• 2003

It is important to control the processing conditions to maximize the replication quality of UV-molded microstructure. In the present study, the tip radius anil surface roughness of V-groove structure were measured to quantify the replication quality. UV-curing dose and the applied pressure were experimentally selected as the governing Processing conditions that affect the replication quality of the UV-molded part. Finally. an experimental optimization technique combining central composite design and desirability function approach was used to maximize the replication quality of UV-molded structure.

• 한국기계가공학회지
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• 제14권3호
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• pp.85-91
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• 2015

The press-fit shaft is an important part used in automobiles, vessels, and trains. This study proposes an optimized design method to reduce damage that may occur in the press-fitted shaft by modifying the shape of the boss step of the press-fitted shaft. To reduce the time and cost of running the optimized design method, an approximate design optimization is applied and an optimized algorithm is generated using a genetic algorithm that is widely used in engineering fields and an approximate model using a response surface method. The planned experiments for the data that are needed to generate the approximate model use a central composite design (CCD) and Latin hypercube sampling (LHS), and the results of the approximate optimization using the above two design of experiments are to be compared.

• Tribology and Lubricants
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• 제23권2호
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• pp.49-55
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• 2007

A numerical analysis of elastohydrodynamic lubrication of elliptical contacts with both rolling and spinning has been carried out. A finite difference method with non-uniform grid systems and the Newton-Raphson method are applied to solve the problems. The velocity vectors resulting from combined spinning and rolling/sliding motion lead to asymmetric pressure distributions and film shapes. Pressure distributions, film contours and variations of the minimum and central film thicknesses are compared with various spin-roll ratios. Reduction of the minimum film thickness under spinning is remarkable whereas the central film thickness is relatively less. The spin motion have large effect on variations of the minimum film thickness with load parameter which are small in pure rolling/sliding cases. Therefore present numerical scheme can be used in the analysis of general elliptical contact EHL problems and further studies are required.

• Journal of Welding and Joining
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• 제19권2호
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• pp.208-214
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• 2001

In this study, we constructed a visual sensor system for weld seam tracking in real time in GMA welding. A sensor part consists of a CCD camera, a band-pass filter, a diode laser system with a cylindrical lens, and a vision board for inter frame process. We used a commercialized robot system which includes a GMA welding machine. To extract the weld seam we used a inter frame process in vision board from that we could remove the noise due to the spatters and fume in the image. Since the image was very reasonable by using the inter frame p개cess, we could use the simplest way to extract the weld seam from the image, such as first differential and central difference method. Also we used a moving average method to the successive position data or weld seam for reducing the data fluctuation. In experiment the developed robot system with visual sensor could be able to track a most popular weld seam. such as a fillet-joint, a V-groove, and a lap-joint of which weld seam include planar and height directional variation.