• Journal of the Optical Society of Korea
• /
• v.13 no.2
• /
• pp.184-192
• /
• 2009

There are total eight degrees of freedom in designing a three-mirror system. If we correct four kinds of third order aberrations and the system should have the specified effective focal length, the remaining three degrees of freedom can be used for selecting a suitable configuration for a specific application. We suggest an analytic design procedure for a three-mirror telescope system which has a suitably sized secondary mirror and proper separations between mirrors, and is corrected for four kinds of third order aberrations, spherical aberration, coma, astigmatism, and field curvature. Two design examples are shown. One has a compact configuration with off-axial field, the other has relatively long configuration with annular ring field.

• Journal of Chest Surgery
• /
• v.44 no.3
• /
• pp.247-249
• /
• 2011

We report a case of pseudo-pseudoaneurysm, which is a very rare complication of myocardial infarction. A 69-year-old man was admitted to our clinic with chest tightness and dyspnea. He had undergone aortic valve replacement with a pericardial bioprosthetic valve, ring mitral annuloplasty, and reconstruction of an aortic annular defect due to infective endocarditis with bovine pericardium 4 years prior. Echocardiography and computed tomography showed pericardial effusion and a 16-mm cavity at the anterolateral wall of the left ventricle. Magnetic resonance imaging suggested either pseudo-pseudoaneurysm or myocardial abscess. We successfully repaired the myocardial defect using a patch made from a vascular graft with pledgeted horizontal mattress sutures under cardiopulmonary bypass.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.10 no.1
• /
• pp.76-80
• /
• 2007

Colorectal carcinomas are extremely rare in childhood and adolescence; however, the colon is the most common site of a gastrointestinal carcinoma. Mucin secreting adenocarcinomas with signet ring formation is the most common type of colon cancer identified in children. An 11-year-old boy had abdominal pain and weight loss for three months, back pain and left thigh pain for two months, and hematochezia for four days. Colonoscopy showed an annular mass in the sigmoid colon and the histopathology revealed a signet ring cell carcinoma. A metastatic signet ring cell carcinoma was suspected from the findings of the bone scan, and confirmed later by a left scalp mass incisional biopsy and a bone marrow biopsy. We report a case of a metastatic signet ring cell carcinoma of the colon in a child.

• Journal of Chest Surgery
• /
• v.41 no.4
• /
• pp.489-491
• /
• 2008

A 52-year-old man was taken to the emergency room following a motor vehicle accident. An echocardiogram showed moderate to severe tricuspid regurgitation due to rupture of the anterior chordae. An operation to repair the tarumatic tricuspid regurgitation was recommended; however, the patient refused because he was asymptomatic. Two years later, he developed mild generalized edema and dyspnea. The echocardiogram revealed progressive severe tricuspid regurgitation and annular dilatation. We treated the tricuspid regurgitation successfully using artificial chordae and ring annuloplasty.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.243.1-243.1
• /
• 2016

Recently, many groups have attempted to fabricate 3-dimensional (3D) structures of GaN such as pyramids, rods, stripes and annulars. Since quantum structures on non-polar and semi-polar planes of 3D structures have less influence of internal electric filed, multi quantum wells (MQWs) formed on those planes have high quantum efficiency. Especially, pyramidal and annular structures consist of various crystal planes with different emission wavelength, providing a possibillity of phosphor-free white light emtting diodes (WLEDs).[1] However, it still has problem to obtain high color rendering index (CRI) number because of narrow-band emission and poor indium composition caused by the formation of few number of facets during metal-organic chemical vapor deposition growth.[2] If we can fabricate 3D structure having more various facets, we can make broad-band emittied WLEDs and improve CRI number. In this study, we suggest a simple method to fabricate 3D structures having various facet and containing high indium composition by means of a combination of metal-organic chemical vapor deposition and wet chemical etching techniques.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.51 no.1
• /
• pp.35-41
• /
• 2015

The age and growth of the Marbled sole, Pleuronectes yokohamae were investigated using left sagittal otoliths of 832 individuals collected in the mid-southern waters of Korea from January 2006 to April 2007. The seasonal changes in the ratio of an translucent zone to interval between annular rings revealed that the boundaries between translucent and opaque parts of the otolith were annual growth rings formed between May and June once a year. The spawning period was November to March and therefore the duration from fertilization to the complete formation of the annual growth ring became fifteen months. The parameters of von Bertalanffy growth equations estimated using the average standard length at each age are the $L_{\infty}$ of 48.04cm, K of 0.1406/year and $t_0$ of -0.5116 for female and 26.14cm, 0.3056/year and -0.8202 for male, respectively. Finally, it is suggested that the growth of female is faster than that of male from age-2.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.49 no.3
• /
• pp.261-269
• /
• 2013

The age and growth of the Pacific cod, Gadus macrocephalus were investigated using left sagittal otoliths of 682 individuals collected in the West Sea of Korea from January to December 2007. The seasonal changes in the ratio of an opaque zone to interval between annular rings revealed that the narrow translucent parts of the otolith were annual growth rings formed between February and March once a year. The spawning period was December to January and therefore the duration from fertilization to the complete formation of the opaque zone became thirteen months. From the parameters calculated using the average length when the year ring was formed, the estimated von Bertalanffy growth equations were $L_t=100.0(1-e^{-0.1640(t+0.5247)})$ for females and $L_t=64.6(1-e^{-0.3335 (t+0.3342)})$ for males when is total length in age t.

• 한국기계연구소 소보
• /
• s.18
• /
• pp.75-85
• /
• 1988

The distributor for hydraulic pumps or motors, particularly radial piston motors, include rotary member which has equally both surface shape for dynamic balance and two fixed members, located in both side of rotary member, which have equal surface shape for dynamic balance and circular ring which use to retain predetermined clearance between two fixed members. Rotary member must have valve part for flow-distribution and can have hydrostatic bearing for excellently dynamic balance. At least two annular steps located on said pressure plate which use in compensation of bolt expansion.

• Journal of Chest Surgery
• /
• v.56 no.1
• /
• pp.56-58
• /
• 2023

Untreated severe tricuspid regurgitation (TR) is associated with poor outcomes. Functional TR occurs secondary to dilatation of the annulus and tethering of the leaflets. Ring annuloplasty alone can correct most cases, but is insufficient in cases of severe annular dilatation due to severe leaflet tethering. In such cases, a tricuspid edge-to-edge technique may be an option. However, stitching of the leaflet tips alone is likely to result in tearing of the leaflets. Approximation of the durable chordae tendineae is considered helpful for this problem. Herein, we present the case of a 39-year-old man who had undergone open-heart surgery for acute type A aortic dissection 13 months earlier. A right mini-thoracotomy approach with a beating-heart strategy was used, which did not require unnecessary pericardial adhesiolysis and dissection. This technique had the advantage of reducing the operation time and the risk of bleeding. To summarize, we present a case of tricuspid valve repair in a high-risk patient with severe leaflet tethering that was successfully managed using these methods.

• Journal of Satellite, Information and Communications
• /
• v.10 no.3
• /
• pp.121-126
• /
• 2015

This paper proposes a novel reconfigurable microstrip antenna based on alternating a perturbation structure to achieve circular polarization diversity. The proposed antenna consists of an annular ring microstrip radiator for simultaneously loading stub and slot perturbations which support right- and left-handed circular polarization senses and two PIN diodes for choosing the operating polarization sense. By controlling the states of two PIN diodes between perturbing slot and stub at one diagonal corner of the radiator, reconfigurable circular polarization senses of the proposed antenna are successfully obtained and alternated. The proposed antenna has been theoretically analyzed and experimentally demonstrated at 2.4 GHz of S-band for satellite communication system. The simulation and measurement results of the proposed antenna show in good agreement with the reflection coefficients, axial-ratios, realized antenna gains, and radiation patterns.