• Journal of Chest Surgery
• /
• v.19 no.4
• /
• pp.606-617
• /
• 1986

During the period from November 1981 through June 1986, 18 cases of coronary arterial bypass graft were performed at Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital. They consisted of 13 males and 5 females with the mean age of 49 [range: 28-69 years]. History of myocardial infarction was noted in 50% of the patients and cardiomegaly on chest PA in 2 patients with preserved LV function. On resting EKG, except the evidences of old myocardial infarction, the findings of LVH were noted in 7 cases, acute myocardial infarction in 2, diffuse myocardial ischemia in 1, and significant ventricular arrhythmia in 2 cases. The angina by type of presentation is stable in 3 patients, unstable in 15 patients with resting, postinfarction and progressive angina as the criteria of unstability. The patterns of involvement of significant disease were single vessel involvement [5 cases] double vessel involvement [8 cases], and triple vessel involvement [5 cases] including 5 cases of left main coronary arterial diseases. The pattern of coronary arterial disease in individual patient was one or more stenosis of the proximal left coronary arterial system with or without right coronary involvement, in every case. We performed 9 cases of double bypass and 9 cases of triple bypass with great saphenous vein using single anastomosis technique except in 4 cases, One of the 4 cases is our first case, sequential anastomosis between LAD and diagonal was performed due to shortage of the prepared vein graft. In the other 3 cases, our latest experience, we adopted the left internal mammary artery for the left anterior descending coronary revascularization. The distribution of sites of distal anastomosis revealed more striking predilection to LAD, showing our attention on the significance of the revascularization of LAD system. The ischemic time was 35 minutes per graft and mean number of grafts per patient was 2.5. Of the 18 patients, 13 [77.2%] had complete revascularization, and incomplete in 5 cases with the causes of incompleteness as presented. The early results of operation were as followed: surgical death in 2 [11%], perioperative infarction 2 [11%], need of inotropic support 5 [28%], arrhythmia 2 [11%], wound problem, bleeding, and emotional dysfunction. The actuarial anginal free survival during the period of 6 months through 2 years was 85.2% with excellent symptomatic control according to the angina classification of Canadian Cardiovascular Society.

• Journal of Fashion Business
• /
• v.16 no.4
• /
• pp.152-165
• /
• 2012

The purpose of this study was examining the preference difference of the necktie design for the stripe patterns according to the demographic characteristics. The study method was a research study through a survey. The study subject was the adult men in their from 20's to 50's. The study stimulative was the stripe patterns of man's necktie which were made by Adobe Photoshop 9 with using the color, the arrangement, the interval, and the width of necktie. The results of study are as follows. As the difference analysis result for the color preference for stripe pattern according to the demographic characteristic, men in their 20's preferred most gray series, men whose monthly income is less than two millions won and men of owner-operator preferred most red series, and all the rest of men preferred blue series. As the difference analysis result for the preference of arrangement type, men in their 20's preferred most the stripe pattern of width, students preferred most the stripe pattern of length, all the rest of men preferred most the stripe pattern of diagonal. As the difference analysis result for the preference of stripe interval for necktie, unmarried men, students, men in their 20's, and men engaging in sales/service and production work preferred most the interval of 0.6cm, all the rest of men preferred most the interval of 1.2cm. As the difference analysis result for the preference of necktie width, unmarried men, men in their 20's, men engaging in sales/service and production work, and students preferred most the width of 7cm, all the rest of men preferred most the interval of 8cm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.4
• /
• pp.357-364
• /
• 2015

In this paper, we designed and implemented a PIFA(Planar Inverted F Antenna) + IFA(Inverted F Antenna) hybrid MIMO(Multi Input Multi Output) antenna for the hexa mobile communication service band. By the simultaneous operation both PIFA and IFA using the coupled feeding structure, we tried for application to modern mobile phones that have large ground size. A PIFA is applied to the ground area, and an IFA is applied to no ground small space on top of the phone. A diagonal fed MIMO antenna is implemented PCB embedded type without antenna carrier component. Implemented antenna on the bare board measured within 3 : 1 for VSWR under hexa mobile communication band as CDMA, GSM900, DCS, KPCS, USPCS, and WCDMA. Measured average gains and efficiencies were -5.19~-3.16 dBi and 30.27~48.26 % for the CDMA, GSM900 band, and -9.50~-5.19 dBi and 11.23~30.28 % for the DCS, KPCS, USPCS, WCDMA band. It's shown that studied antenna can be applied to the antenna for the modern mobile phone.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.37-40
• /
• 2008

Many engineers find the way of improving the old building's structural behavior in the remodeling project which is performed using artificial openings for merging two houses. This test was performed to verify the characteristics of coupling beams according to the shape of the openings. One of test specimen has rectangle shape and the other was made by the circle shaped opening and one has coupling member only as slabs. Additionally, three specimens which have openings have 23% ratio in opening area to total wall area. Consequently, solid type which have no opening area shows shear failure. In the case of CW-RBS which have rectangular shaped opening, cracks are developed in coupling beam significantly. And CW-CS which has circular opening failed in shear showing development of diagonal cracks at wall toes and wall mid-height. It is thought that degradation of the wall strength is under the control of the opening shape and coupling beam-wall connection area.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.3
• /
• pp.181-185
• /
• 2016

One of the important issues for fabricating the microelectronic display devices such as FED, PDP, and VFD is to obtain a high vacuum level inside the panel. In addition, sustaining the initial high vacuum level permanently is also very important. In the conventional packing technology using a tabulation method, it is not possible to obtain a satisfiable vacuum level for a proper operation. In case of FED, the poor vacuum level results in the increase of operating voltage for electron emission from field emitter tips and an arcing problem, resultantly shortening a life time. Furthermore, the reduction of a sealing process time in the PDP production is very important in respect of commercial product. The most probable method for obtaining the initial high vacuum level inside the space with such a miniature and complex geometry is a vacuum in-line sealing which seals two glass plates within a high vacuum chamber. The critical solution for the vacuum sealing is to develop a frit glass to avoid the bubbling or crack problems during the sealing process at high temperature of about $400^{\circ}C$ under the vacuum environment. In this study, the suitable frit power was developed using a mixture of vitreous and crystalline type frit powders, and a vacuum sealed CNT FED with 2 inch diagonal size was fabricated and successfully operated.

• Structural Engineering and Mechanics
• /
• v.56 no.5
• /
• pp.813-833
• /
• 2015

Spherical reticulated shells are widely applied in structural engineering due to their good bearing capability and attractive appearance. Parametric modeling of spherical reticulated shells is the basis of internal analysis and optimization design. In the present study, generation methods of nodes and the corresponding connection methods of rod elements are proposed. Modeling programs are compiled by adopting the ANSYS Parametric Design Language (APDL). A shape optimization method based on the two-stage algorithm is presented, and the corresponding optimization program is compiled in FORTRAN environment. Shape optimization is carried out based on the objective function of the minimum total steel consumption and the restriction condition of strength, stiffness, slenderness ratio, stability. The shape optimization of four typical Schwedler spherical reticulated shells is calculated with the span of 30 m~80 m and rise to span ratio of 1/7~1/2. Compared with the shape optimization results, the variation rules of total steel consumption along with the span and rise to span ratio are discussed. The results show that: (1) The left and right rod-Schwedler spherical reticulated shell is the most optimized and should be preferentially adopted in structural engineering. (2) The left diagonal rod-Schwedler spherical reticulated shell is second only to left and right rod regarding the mechanical behavior and optimized results. It can be applied to medium and small-span structures. (3) Double slash rod-Schwedler spherical reticulated shell is advantageous in mechanical behavior but with the largest total weight. Thus, this type can be used in large-span structures as far as possible. (4) The mechanical performance of no latitudinal rod-Schwedler spherical reticulated shell is the worst and with the second largest weight. Thus, this spherical reticulated shell should not be adopted generally in engineering.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.408-413
• /
• 2004

Numerical and experimental investigation were car-ried out to clarify the flow structure of underexpanded jet from a square nozzle. The square nozzle rep-resents one of the clustered combustors of a linear aerospike engine. From the numerical results, the three-dimensional shock wave of the underexpanded square jet was found to be composed of two shocks. One is the intercepting shock which corresponds to the shock observed in two-dimensional planar jet. The other is the recompression shock divided into two types. The expansion fans coming from the nozzle edges interact with each other at the comers of the nozzle exit, and overexpanded regions are generated. Therefore one of the two recompression shocks is formed at the comers of the nozzle exit behind the overexpanded regions. As the jet goes downstream, the overexpanded regions grow larger to coalesce at the symmetry planes. Then, the other type of the recompression shock is generated. The three-dimensional shock structure formed by the intercepting shock and the recompression shocks dominates the expansion of the jet boundary. The shock detection algorithm us-ing CFD results was developed to reveal the relation between the shock waves and the jet boundary, and it was found that the cross-sectional jet shape becomes cross-shape. The key features observed in the numerical investigation were verified by the experimental results. The shock structure at the diagonal plane was in good agreement with the experimental schlieren images. Moreover, the cross-sections visualized by the Mie scattering method confirmed that the cross-section of the jet becomes cross-shape.

• Earthquakes and Structures
• /
• v.8 no.3
• /
• pp.555-572
• /
• 2015

This paper presents an experimental study of three two-dimensional (2D/planar) steel reinforced concrete (SRC) T-shaped column-RC beam hybrid joints and six 3D SRC T-shaped column-steel beam hybrid joints under low cyclic reversed loads. Considering different categories of steel configuration types in column cross section and horizontal loading angles for the specimens were selected, and a reliable structural testing system for the spatial loading was employed in the tests. The load-displacement curves, carrying capacity, energy dissipation capacity, ductility and deformation characteristics of the test subassemblies were analyzed. Especially, the seismic performance discrepancies between planar hybrid joints and 3D hybrid joints were intensively compared. The failure modes for planar loading and spatial loading observed in the tests showed that the shear-diagonal compressive failure was the dominating failure mode for all the specimens. In addition, the 3D hybrid joints illustrated plumper hysteretic loops for the columns configured with solid-web steel, but a little more pinched hysteretic loops for the columns configured with T-shaped steel or channel-shaped steel, better energy dissipation capacity & ductility, and larger interlayer deformation capacity than those of the planar hybrid joints. Furthermore, it was revealed that the hysteretic loops for the specimens under $45^{\circ}$ loading angle are generally plumper than those for the specimens under $30^{\circ}$ loading angle. Finally, the effects of steel configuration type and loading angle on the seismic damage for the specimens were analyzed by means of the Park-Ang model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.1
• /
• pp.92-98
• /
• 2001

When analyzing the scatting problem of multi-layered planar structures using closed-form Green's function, one of the main difficulties is that the numerical integrations for the evaluation of diagonal matrix elements converge slowly and are not so stable. Accordingly, even when the integration fur the singularity of type $e^{-jkr}/{\gamma}$, corresponding to the source dipole itself, is performed using such a method, this difficulty persists in the integration corresponding to the finite number of complex images. In order to resolve this difficulty, a new technique based upon the Gaussian quadrature in polar coordinates for the evaluation of the two-dimensional generalized exponential integral is presented. Stability of the algorithm and convergence is discussed. Performance is demonstrated for the example of a microstrip patch antenna.

• Journal of the Korea Concrete Institute
• /
• v.19 no.1
• /
• pp.83-90
• /
• 2007

The present study reports a simple unbonded-type shear strengthening technique for reinforced concrete beams using wire rope units. Fifteen beams failed in shear were repaired and strengthened with wire rope units, and then retested to failure. Influence of the prestressing force, orientation and spacing of wire rope units on the shear behavior of strengthened beams having shear span-to-depth ratios of 1.5, 2.5, or 3.25 were investigated. Test results showed that beams strengthened with wire rope units exhibited a higher shear strength and a larger post-failure deformation than the corresponding original beams. Inclined wire rope units was more effective for shear strength enhancement than vertical wire rope units. The increase of the prestressing force in wire rope units causes the decrease of the principal tensile stress in concrete, as a result, the diagonal tensile cracking strength of strengthened beams was higher than that of the corresponding original beams. Shear capacity of strengthened beams is compared with predictions obtained from ACI 318-05 and EC 2. Shear capacity of strengthened beams having shear span-to-depth ratio below 2.5 is reasonably predicted using ACI 318-05 formula. On the other hand, EC 2 overestimates the shear transfer capacity of wire rope units for beams having shear span-to-depth ratio above 2.5.