• Journal of Embryo Transfer
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• v.28 no.1
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• pp.73-78
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• 2013

The present study examined the histological characteristics of adult testis in the long-beaked common dolphin (Delphinus capensis) from Korean waters and the localization of DEAD-box polypeptide 4 (DDX4; a germ cell marker) and vimentin (a Sertoli cell marker) expression in the dolphin testis compared with that in terrestrial mammals, including dogs and rats. The seminiferous tubules of dolphin testis have very small or completely closed lumens, and spermatogenic cells and Sertoli cells within the tubules cannot be differentiated. Immunohistochemical analysis showed that, in the dolphin testis, DDX4- and vimentin-positive cells were scattered extensively within the tubule, whereas in the dog and rat testis, DDX4 immunoreactivity was localized in spermatogenic cells of the adluminal compartment, and vimentin immunoreactivity was localized in Sertoli cells of the basal compartment in the seminiferous epithelium. These results suggest that the histological characteristics of the seminiferous tubules in the dolphin testis differ from those of terrestrial species.

• Korean Journal of Materials Research
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• v.23 no.3
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• pp.183-189
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• 2013

$Cu_2ZnSn(S,Se)_4$ material is receiving an increased amount of attention for solar cell applications as an absorber layer because it consists of inexpensive and abundant materials (Zn and Sn) instead of the expensive and rare materials (In and Ga) in $Cu(In,Ga)Se_2$ solar cells. We were able to achieve a cell conversion efficiency to 4.7% by the selenization of a stacked metal precursor with the Cu/(Zn + Sn)/Mo/glass structure. However, the selenization of the metal precursor results in large voids at the absorber/Mo interface because metals diffuse out through the top CZTSe layer. To avoid the voids at the absorber/Mo interface, binary selenide compounds of ZnSe and $SnSe_2$ were employed as a precursor instead of Zn and Sn metals. It was found that the precursor with Cu/$SnSe_2$/ZnSe stack provided a uniform film with larger grains compared to that with $Cu_2Se/SnSe_2$/ZnSe stack. Also, voids were not observed at the $Cu_2ZnSnSe_4$/Mo interface. A severe loss of Sn was observed after a high-temperature annealing process, suggesting that selenization in this case should be performed in a closed system with a uniform temperature in a $SnSe_2$ environment. However, in the experiments, Cu top-layer stack had more of an effect on reducing Sn loss compared to $Cu_2Se$ top-layer stack.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.101-104
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• 2000

Nowadays, the issue of congestion control in high-speed communication networks becomes critical in view of the bandwidth-delay products for efficient data flow. In particular, the fact that the congestion is often accompanied by the data flow from the high-speed link to low-speed link is important with respect to the stability of closed-loop congestion control. The Virtual-Connection Network (VCN) in Gigabit Ethernet networks is a packet-switching based network capable of implementing cell- based connection, link-by-link flow-controlled connection, and single- or multi-destination virtual connections. VCN described herein differ from the virtual channel in ATM literature in that VCN have link-by-link flow control and can be of multi-destination. VCNs support both connection-oriented and connectionless data link layer traffic. Therefore, the worst collision scenario in Ethernet CSMA/CD with virtual collision brings about end-to-end delay. Gigabit Ethernet networks based on CSMA/CD results in non-deterministic behavior because its media access rules are based on random probability. Hence, it is difficult to obtain any sound mathematical formulation for congestion control without employing random processes or fluid-flow models. In this paper, an analytical method for the design of a congestion control scheme is proposed based on Smith＇s principle to overcome instability accompanied with the increase of end-to-end delays as well as to avoid cell losses. To this end, mathematical analysis is provided such that the proposed control scheme guarantees the performance improvement with respect to bandwidth and latency for selected network links with different propagation delays. In addition, guaranteed bandwidth is to be implemented by allowing individual stations to burst several frames at a time without intervening round-trip idle time.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.635-656
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• 1991

It was the aim of this investigation to evaluate some histologic aspect of rat pulp tissue after it had been compromised by an experimental orthodontic force. Experimental animals of thirty five Spraque-Dawley rats were employed. The first upper molars had been successively mesial moved (initial load 100 gr.) with a closed coil spring during 21 days. The experimental periods were set on immediate, 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks following retention time. On each experimental period, the rats were killed and prepared for the light microscopy. After prepared with H/E stain and Gomori's one-step trichrome stain, the specimens were analyzed with evaluation criteria which were adopted in this study. The result may be summarized as follows; 1. The main pulp changes due to experimental orthodontic force included vacuolization of odontoblastic layer, circulation disturbance, root resorption, reduced pulp collagenous fiber density and mean cell count of pulp fibroblast in the immediate group. 2. The pulp tissue changes were revealed reversible because the relieved pulp tissues from experimental orthodontic force were recovered rapidly in each evaluation criteria during retention periods. 3. Compared with normal control group, pulp collagenous fiber density were decreased in immediated group (p < 0.01), but increased in each retention groups. These seem to suggest that the pulp tissues were aged after experimental orthodontic force conditions. 4. Compared with normal control group, mean cell counts of pulp fibroblasts were decreased in immediate group (p < 0.05), but increased continuous in each retention groups. These seem to indicate that the pulp tissues were highly regenerative after experimental orthodontic force conditions. 5. Compared with normal control group, root resorptions occurred in all immediate specimens (p < 0.01) and they were healed in each retention periods, but often observed in 4 weeks retention group. These seem to indicate that root resorptions were recovered slowly after experimental orthodontic force conditions.

• Journal of Chest Surgery
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• v.22 no.5
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• pp.839-844
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• 1989

There appears to be significant problems remained in the treatment of tuberculous empyema with BPF in spite of several surgical methods: decortication, thoracoplasty, and pleuropneumonectomy. We presented one case of tuberculous empyema with BPF. The patient was 42-year-old male and his chief complaint was hemoptysis. In past history, he was treated with left closed thoracostomy and antituberculous medication for two months, 16 years ago. Chest X-ray, tomogram and C. T, revealed a huge mass with central necrosis in the lower 2/3 of left thoracic cavity and shifting of the mediastinal structure to the right. Needle aspiration cytology was undifferentiated large cell carcinoma. Left thoracotomy was made under the impression of lung cancer and pleuropneumonectomy was done. Operative findings; thick walled empyema sac filled with hematoma and BPF, the mediastinum was fixated due to fibrosis and calcification of the pleura and the mediastinum. Postoperative biopsy was consistent with tuberculosis. In the postoperative course, there was massive hemorrhage and so reoperation was done. But there was no active bleeding focuses in the thoracic cavity at the time of reoperation. Massive transfusion, coagulant therapy and intermittent clamping and declamping of the chest tube were carried out. Especially, serum calcium level was chronically decreased and so large amount of calcium gluconate was infused for the calcium level to be normal. Total transfused blood; whole blood was 33 pints, packed cell was 63 pints and fresh frozen plasma was 70 pints. At the postoperative[reop] 45th day, intrathoracic hemorrhage was stopped and the chest tube was removed. In conclusion, this suggest that uncontrollable bleeding after pleuropneumonectomy of the tuberculous empyema with BPF could be treated without reoperation in case of the mediastinal fixation due to fibrosis and calcification of the pleura and the mediastinum.

• Journal of Chest Surgery
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• v.29 no.12
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• pp.1381-1384
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• 1996

Thymoma Is an anterior mediastinal tumor, arising from the thymus, but occasionally has ectopic focus such as neck, trachea, thyroid, pulmonary hilum, lung parenchyme and pleura. Forty-two year old male patient was admitted due to progressive development of shortness of breath in 4 months. He had a history of exposure to asbestos for About 10 years duration In recent 15 years. Radiologically, multiple pleural masses were seen rom apex to diaphrAgm, with no evidence of anterior mediastinal mass,with fluid in right pleural cavity. Closed thoracotomy drainage with open biopsy were performed. Effusion cell block showed many T cell marker positive Lymphocytes & some epithelial cells compatible with thymoma, and the tissue also showed cortical type thymoma. Pleuropneumonectomy and thymectomy followed by 60 Gy radiation therapy were done and the patient is well 8 months postoperatively. The pleura is markedly thickened by the invasion of thymoma and the interstitial space of the lung tissue,but the normal appearance of thymus was present in remote area (Masaoka classification IVa). We report a case of ectopic invasive thymoma arising from the right pleura with intact thymus.

• Korean Journal of Veterinary Research
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• v.35 no.3
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• pp.417-425
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• 1995

The regional distribution and relative frequencies of gastrointestinal endocrine cells were studied immunohistochemically in the GIT of the cat-shark. Five kinds of endocrine cells were identified in this study. Mostly these cells were of open types, except for glucagon-, BPP- and somatostatin-immunoreactive cells in the stomach which seemed to be of closed type. 5-HT-immunoreactive cells were detected throughout the GIT, and were more freguent than of the other regions. Glucagon-and BPP-immunoreactive cells were demonstrated in the entire GIT except for the duodenum an the rectum, and occurred in various frequencies. A few numbers of Gas/CCK-immunoreactive cells were restricted to the duodenum. Somatostatin-immunoreactive cells were distributed in the whole GIT, and were a few in numbers in the stomach and rare in the intestine, respectly. These results suggest that the pattern of the regional distribution is rather similar to that reported fur previously, but relative number was less frequent than that of other species.

• Korean Journal of Veterinary Research
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• v.42 no.3
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• pp.289-297
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• 2002

The regional distribution and relative frequency of neurohormonal peptides-producing cells were demonstrated in the gut of the stomach teleost, the Mandarin fish, Siniperca scherzeri Steindachner, using 7 types of specific antisera raised against mammalian regulatory peptides. The gastrointestinal tract of the Mandarin fish was divided into three portions from proximal to distal, stomach, small intestine and large intestine. Cells showing immunoreactivities against regulatory peptides were situated in the epithelial lining, between epithelial cells, and gastric or intestinal gland regions with various frequencies along with gastrointestinal tract. Mast of immunoreactive cells in the epithelial lining portion were generally spherical or spindle shape having long cytoplasmic process that were reached to the lumen (open type cell) while cells showing round in shape (closed type cell) were found in the gastric gland of the stomach occasionally. Serctonin-, samatostatin-, gastrin-, cholecystokinin (CCK)-8- and human pancreatic polypeptide (HPP)-immunoreactive cells were observed in this study. However, no insulin- and glucagon-immunoreactive cells were found. Serotonin- and somatostatin-immunoreactive cells were restricted to the stomach regions with moderate and numerous frequencies, respectively. Gastrin-immunoreactive cells were demonstrated in the stomach and small intestinal portions with a few and moderate frequencies, respectively and CCK-8-immunoreactive cells were restricted to the small intestinal portions with moderate frequency. In addition, HPP-immunoreactive cells were demonstrated in the stomach and small intestine with numerous frequencies, respectively. In conclusion, the distribution and relative frequency of these immunoreactive cells in the gastrointestinal tract of the Mandarin fish shows peculiar patterns compared to those of other stomach and/or stomachless teleost.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.4
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• pp.497-509
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• 1996

Evacuated powder insulations have long been known to have better thermal performance than existing commercially available insulators, such as fiber glass and CFC-blown foam. To make a composite powder panel, a series of individually evacuated panels was encapsulated in a rigid closed cell foam matrix. The panels were encapsulated in a thin glass sheet barrier to preserve the vacuum. The thermal conductivity of the individual panel was found to be $0.0062W/m^{\circ}K$ by experiment and the polyurethane foam above had a thermal conductivity of $0.024W/m^{\circ}K$. In this study, numerical analysis using finite element method was carried out to investigate insulation performance of rigid foam/evacuated powder composite panel with respect to panel geometries such as panel pitch, panel aspect ratio and panel area ratio. Numerical analysis has indicated that more optimal vacuum panel geometries, much lower overall thermal conductivities can be achieved.

• Steel and Composite Structures
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• v.21 no.5
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• pp.1105-1119
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• 2016

In this study, it is presented that a new developed approach for equivalent area-distributed loading (EADL) induced from a single concentrated force. For the purpose, a full scale 3D steel formwork system was constructed in laboratory conditions. A developed load transmission platform was put on the formwork system and loaded step by step on the mass center. After each load increment, displacement was measured in several crictical points of the system. The developed platform which was put in to slab of formwork to equivalently distribute the load from a point to the whole slab was constituted using I profiles. A 3D finite element model of the formwork system was analyzed to compare numerical displacement results with experimental ones. In experimental tests,difference among the displacements obtained from reference numerical model (model applied EADL) and main numerical model (model applied single load using a load cell via load transmission platform) is about %13 in avarage. Difference among the displacements obtained from experimental results and main numerical model under 30 kN single load is about %11 in avarage. The results revealed that the displacements obtained experimentally and numerically are dramatically closed to each other. It is highlighted from the study that the developed approach is reliable and useful to get EDL.