• Applied Microscopy
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• 제26권2호
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• pp.221-233
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• 1996

In order to study process of spermiogenesis of the Korean manchurian field mouse, Apodemus spesiosus peninsulae, the testis obtained from sexually matured male reproductive organs, were examined with electron microscopy, and the following results were obtained based on the characters of cell differentiation. 1. According to the features of cell structure, spermiogenesis of the Apodemus spesiosus peninsulae was five phases: Golgi, cap, acrosome, maturation and spermiation phase. They were further subdivided into two steps of early and late phases respectively. Hence, the spermiogenesis consists of ten steps. 2. In the changes of the chromatin, the chromatin granules began to be condenced in the cap phase and regularizated at maturation phases, and a perfect nucleus of sperm was formed at the spermiation phases. 3. The formative period of sperm tail began to be develop in the early Golgi phase and completed at the spermiation phases 4. The outer dence fibers of middle piece were arranged in a horseshoe fashion. Nos. 1, 5, 6 and 9 of the outer dense fibers were larger than the others. The structure of axoneme in the middle piece was 9+2, and the axonemal complex consists of A and B microtubules, dynein arms and radial links.

• Childhood Kidney Diseases
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• 제13권2호
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• pp.256-260
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• 2009

The Russell-Silver syndrome (RSS) is a disease characterized by intrauterine growth retardation with preserved head circumference, facial dysmorphism and short stature. Reported renal and urinary manifestations of RSS include horseshoe kidney, renal tubular acidosis, hydronephrosis, ureteropelvic obstruction and vesicoureteral reflux. Here we report a case of end-stage renal disease associated with RSS, which, to the best of our knowledge, has not been reported yet.

• Structural Engineering and Mechanics
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• 제31권6호
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• pp.679-696
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• 2009

The paper aims at analyzing the stress distribution around an underground opening that is subjected to non-symmetrical surface loading with emphasis on opening shapes with sharp corners and the stress concentrations developed at these locations. The analysis is performed utilizing the BIE method coupled with the Neumann's series. In order to implement this approach, the special recurrent relations for half plane were proven and the modified Shanks transform was incorporated to accelerate the series convergence. To demonstrate the capability of the developed approach, a horseshoe shape opening with sharp corners was investigated and the location and magnitude of the maximum hoop stress was calculated. The dependence of the maximum hoop stress location on the parameters of the surface loading (degree of asymmetry, size of loaded area) and of the opening (the opening height) was studied. It was found that the absolute magnitude of the maximum hoop stress (for all possible surface loading locations) is developed at the roof points when the opening height/width ratio is relatively large or when the pressure loading area is relatively narrow (compared to the roof arch radius), and contrarily, when the opening height/width ratio is relatively small or when the surface pressure is applied to a relatively wide area, the absolute magnitude of the maximum hoop stress is developed at the bottom sharp corner points.

• Geomechanics and Engineering
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• 제15권2호
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• pp.775-781
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• 2018

Shake table tests were conducted on scaled tunnel model to investigate the mechanism and effect of seismic loadings on horseshoe scaled tunnel model in ground fissure site. Key technical details of the experimental test were set up, including similarity relations, boundary conditions, sensor layout, modelling methods were presented. Synthetic waves and El Centro waves were adopted as the input earthquake waves. Results measured from hanging wall and foot wall were compared and analyzed. It is found that the seismic loadings increased the subsidence of hanging wall and lead to the appearance and propagation of cracks. The values of acceleration, earth pressure and strain were greater in the hanging wall than those in the foot wall. The tunnel exhibited the greatest earth pressure on right and left arches, however, the earth pressure on the crown of arch is the second largest and the inverted arch has the least earth pressure in the same tunnel section. Therefore, the effect of the hanging wall on the seismic performance of metro tunnel in earth fissure ground should be considered in the seismic design.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제31권3호
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• pp.353-358
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• 1998

Experiments were performed to find out the physico-chemical properties of milt, and morphological changes of cryopreserved spermatozoa in tiger puffer, Takifugu rubripes. The average number of sperm and spermatocrit in milt stripped were $9.81{\pm}0.34{\times}10^{10}/m{\ell}$ and $97.8{\pm}0.8$, respectively. While total lipid concentration from seminal fluid was higher than that from sperm, total protein concentration from sperm was higher than that from seminal fluid, Na and K concentrations in sperm and those in seminal fluid were similar each other, However, glucose from sperm and seminal fluid were not detectable. Spermatozoon of tiger puffer was consisted of head, middle Piece and tail. Size of head showing horseshoe shape was $0.65{\pm}0.10{\mu}m$ in diameter and $1.35{\pm}0.30{\mu}m$ in length. The head fully containing chromatin did not have acrosome. Mitochondrion in middle piece was $0.2{\mu}m$ in average diameter and flagellum showed 9+2 structure. A few of cryopreserved spermatozoa showed morphologically loose or swollen plasma membranes.

• Transactions of the Korean Society of Mechanical Engineers
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• 제14권2호
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• pp.470-483
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• 1990

Turbulent jet in a crossflow, issuing from a row of holes on a convex surface of 90 .deg. bend duct, is predicted by a 3-dimensional numerical method. The Cartesian coordinate system in adopted in upstream and downstream tangents and the cylindrical polar coordinate system in curved region. The Reynolds stresses and heat fluxes are obtained from a standard k-e model in the core region and van Driest model in the vicinity of the wall. The governing equations are discretized by a finite volume method and solutions are obtained by a locally elliptic calculation procedure. Pressure and convective terms are treated by SIMPLE algorithm and hybrid scheme respectively. A vortex initially induced by the injected jet has been built up due to the interaction with the secondary flow caused by pressure gradient and centrifugal force. The vortex structure has a strong influence on the wall cooling effectiveness. Another vortex like horseshoe is formed in the vicinity of the injection hole and its strength is getting weak as it moves downward.

• Journal of Mechanical Science and Technology
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• 제16권1호
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• pp.109-115
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• 2002

Vortex generators are fabricated on the fin surface of a fin-tube heat exchanger to augment the convective heat transfer. In addition to horseshoe vortices formed naturally around the tube of the fin-tube heat exchanger, longitudinal vortices are artificially created on the fin surface by vortex generators. The purpose of this study is to investigate the local heat transfer phenomena in the fin-tube heat exchangers with and without vortex generators, and to evaluate the effect of vortices on the heat transfer enhancement. Naphthalene sublimation technique is employed to measure local mass transfer coefficients, then analogy equation between heat and mass transfer is used to calculate heat transfer coefficients. Experiments are performed for the model of fin -circular tube heat exchangers with and without vortex generators, and of fin-flat tube heat exchangers with and without vortex generators. Average heat transfer coefficients of finn-flat tube heat exchanger without vertex generator are much lower than those of fin-circular tube heat exchanger. On the other hand, fin-flat tube heat exchanger with vortex generators has much higher heat transfer value than conventional fin-circular tube heat exchanger At the same time, pressure losses for four types of heat exchanger is measured and compared.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권3호
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• pp.150-157
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• 2003

Local and overall heat transfer characteristics of fin-flat tube heat exchangers with and without vortex generators were investigated. Local heat transfer coefficients were measured with the heat exchanger model using naphthalene sublimation technique. In case of a fin-flat tube heat exchanger without vortex generators, only the horseshoe vortices formed around tubes augment the heat transfer. On the other hand, longitudinal vortices created artificially by vortex generators additionally enhance heat transfer in case of a fin-flat tube heat exchanger with vortex generators. Overall heat transfer coefficients were measured with the prototypes of the fin-flat tube heat exchanger with and without vortex generators in a wind tunnel and results were compared with those of a fin-circular tube heat exchanger with wavy fin. Friction losses for heat exchangers were also measured and compared. The fin-flat tube heat exchanger with vortex generators is found to be more effective than the fin-circular tube heat exchanger with wavy fin.

• Journal of the Korean Society of Costume
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• 제54권2호
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• pp.25-38
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• 2004

The purpose of this study is to analyze the fashion style in the drama 'sex and the city's character. Frist of all, mixing and matching style is one of Carrie's signiture styles, namely her ability to combine haute couture fashion with high street bargains and vintage buys to make ingenious ensambles. There are two main ways to go with this seperates look, the equal look, when tops are put with equally fabulous bottoms, and the unequal look, when fabulous tops go with less fabulous bottoms. Second, nowadays vintage style is one of fashion trend. The 'Sex and the city' has define trends when it comes to jewellery, it is the 'Carrie' nameplate and the Hermes's horseshoe necklaces, especially pearls were a big hit for vintage style. Also it takes a floral pattern and various hat makes a vintage style. Third, Sexual style shows a halter and sleeveless dress with long earing and splendid necklaces. And it takes a leopard pattern. Fourth, romantic style, one of the 'Sex and the city"s character's favourite garments is the dress. Its makes romantic moods a delicate with handbags, Manolo Blahnik's and Jimmy Choo's high hill shoes and corsages. The romantic pattern is floral and material is chiffon.ffon.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제25권12호
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• pp.1861-1868
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• 2001

Vortical structures in the near-wake region of a cubic obstacle are studied using numerical simulation. We consider flow between two parallel plates with a cube mounted on one of the plates. In the turbulent near-wake region of the flow, coherent structures such as hairpin vortices are found. Quasi-periodic behavior of the hairpin vortices is noticed; its dimensionless frequency at Re=1,000 is about 0.82 which is consistent with the result of Elavarasan of et al.'s experiment [Fluid Dyn. Research, 2000, 27] although their geometry is somewhat different from on. In the case of Re=3,500, the dimensionless frequency of the hairpin vortex is about 1.60. It is observed that the translating speed of the head of the hairpin vortex is lower than the streamwise mean velocity at that location. In the vicinity of the lower plate downstream of the cube, various length scales are identified thus less coherent. However, it is noticed that the vortical structures become gradually elongated downstream of the new reattachment.