• Korean Journal of Veterinary Research
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• v.29 no.4
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• pp.417-424
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• 1989

This study was conducted in order to observe the changes in cellular association of seminiferous tubules from 4 to 22 weeks of age and to obtain the cycle and relative duration of seminiferous epithelia from 24 weeks of age in male ducks. Fifety-five male ducks were used in the experiment and divided into 11 groups, consisting of 5 male ducks each, with 2 weeks intervals from 4 to 24 weeks of age. The results were summarized as follows: 1. The body and testes weight showed most rapid increase during 4 to 6 weeks and 18 to 22 weeks of age, respectively. The seminiferous tubules were obruptly enlarged in diameter of tubules during 18 to 22 weeks of age. 2. Gonocytes were seen from 4 to 6 weeks of age, however they were not observed as from 8 weeks of age. Both type Ap spermatogonia and type Ad spermatogonia occured from 8 to 12 weeks of age, while spermatocytes and spermatids were beginning to appear at 16 weeks and 18 weeks of age, respectively. Spermatozoa were first observed at 20 weeks of age. Full spermatogenic activity was completed at the age of 20 weeks. 3. Average paired weight of the testes in male ducks was 78g at 24 weeks of age and its ratio to the body weight was approximately 2.5 percent. 4. Average diameter of seminiferous epithelium at 22 weeks of age was $232{\mu}m$, and average numbers of Sertoli cell, spermatogonia, spermatocyte, spermatids and spermatozoa in the cross section of seminiferous epithelium were 15.30, 59.08, 41.78, 71.11 and 165.30, respectively. Spermatogonia and spermatids were classified into 2 and 4 types, respectively. 5. The cycle of the seminiferous epithelium could be divided into 5 stages at 24 weeks of age. The relative frequencies of stages from I to V were 13.5%, 25.0%, 22.3%, 20.6% and 18.7% respectively. Thus, establishment of spermatogenesis in male ducks were beginning to appear at 20 weeks of age.

• Korean Journal of Veterinary Research
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• v.31 no.4
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• pp.355-365
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• 1991

This study was conducted in order to observe the changes in cellular association of seminiferous tubules from 16 to 24 weeks of age and to obtain the cycle and relative duration of the seminiferous epithelia from 28 to 44 weeks of age in Korean native dogs. The results were summarized as follows; 1. Gonocytes were seen at 16 weeks of age, however they were not observed as from 20 weeks of age. Both type A and type B-spermatogonia occurred from 20 weeks, while primary spermatocytes were found from 20 weeks. Secondary spermatocytes and spermatids appeared from 28 weeks. Spermatozoa were observed at first at 28 weeks of age. 2. Type A-spermatogonia appeared approximately 1.6 times as many at stage II compared to stage I, while the same numbers of cells were seen in both stage I and VII, showing the least number among VIII stages of the cycle of the seminiferous epithelia. The type B-spermatogonia were found from stage VI to VIII, Leptotene phase of the primary spermatocyte divided from type B-spermatogonia in stage VII observed at the stage VIII. Pachytene phase of the primary spermatocytes were shown the least in number at stage IV. The secondary spermatocyte could be seen only at stage IV. 3. The relative frequency of each stage from stage I to VIII of the cycle of the seminiferous epithelia was 30.3, 12.0, 9.8, 4.2, 8.5, 10.5, 11.4 and 13.4% respectively. Thus the establishment of spermatogenesis in Korean native dog was completed from 28 weeks of age.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.345-354
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• 2010

This paper presents an experimental investigation of the structural performance of a large-span girder bridge with an under-tension system. Typical long-span structures with beam and girder members have greater structural member depths and sizes to carry the moment and deflection. An under-tension system can be an effective structural system, as it allows the cables to resist some portions of the vertical loadings and deflections. To evaluate the serviceability and ultimate strength of the under-tension system, two $10m{\times}2.4m$ experimental under-tension systems were built and tested. One was developed with an H-beam section, and the other was made with a PF500 section that had the advantages of fast construction and lower construction cost. In the test, the maximum deflections at the mid-point of both beams were effectively reduced using under-tension systems. Also, the increased tension forces in the cable reduced the deflections. The PF500 members, which had a new shape and were developed using the module systems, performed better than the typical H-beam sections in terms of the deflections and ultimate strength.

• Journal of Korean Association for Spatial Structures
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• v.10 no.2
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• pp.117-126
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• 2010

Experiment on flexural analysis of RC beams strengthened with composite material panel is presented. Recently, the strengthening of reinforced concrete structures using advanced fiber reinforced plastic (FRP) composites, and in particular the behavior of FRP-reinforced concrete structure is topic that has become very popular because of good corrosion resistance and easy for site handling due to their light weight. In this study, an efficient computational analysis using ABAQUS to predict the ultimate moment capacity of reinforced concrete beams strengthened with FRP is presented. Test parameters in this study are the shape of fiber arrangement (LT, DB, DBT) and the number of carbon fiber sheets (2ply, 3ply). When comparing with results of the analytical model, results of the experiments show similar values. Furthermore, reinforced concrete beam with FRP obtains improved effects for ultimate strength.

• Journal of Korean Association for Spatial Structures
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• v.10 no.2
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• pp.87-94
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• 2010

Form-Finding of tensegrity structures by eigenvalue problem is presented, In ardor to maintain the structures stable, "Form-Finding" should be performed. The types of analytical methods are known to solve this phenomenon: One is to use force density method, and the other is to apply so called, generalized inverse method. In this paper, new form finding methods are presented to obtain the self-equilibrium stress of the tensegrity structures. This method is based on the equilibrium equation of the all of the joint and the governing equation is formulated as eigonvalue problem. In order to verify this approach, numerical example(tensegrity structures) are compared with others calculated by previous methods. The solution by present method is shown identical results. Furthermore, the developed process to find the results is more efficient than previous approaches.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.190-196
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• 2004

Yttrium Aluminum Garnet (YAG) powders were synthesized by precipitation of solutions of Al and Y nitrates using ammonium hydrogen carbonate as a precipitant. Y$_2$O$_3$ and YAG phases were formed in the precipitates, which had been attrition-milled. Well-crystallized, phase-pure YAG powders were obtained after calcination of the milled precipitates at 1100$^{\circ}C$ for 1 h. The powders were found to exhibit an excellent sinterability regardless of the addition of SiO$_2$(500 ppm Si) as a sintering aid. All samples already densified to relative densities greater than 70% at 1300$^{\circ}C$ and relative densities of ∼83％ at 1400$^{\circ}C$. The samples doped with SiO$_2$ showed a little improvement in densification as compared with those for the undoped samples and resulted in a relative density of 97% at 1600$^{\circ}C$.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.11
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• pp.1297-1306
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• 2015

The introduction of multimedia 119-notification service utilizing smart devices causes firefighters to be more exposed to emotional labor. The purpose of this study is to investigate the effect of increased emotional labor of firemen on job satisfaction. As a result, the higher the emotional labor of firefighters is, the higher job stress (${\beta}=0.166$, p=0.000) and social support(${\beta}=0.540$, p=0.000) are. But job satisfaction tends to be lower(${\beta}=-0.136$, p=0.000). As they play an important role to protect the safety and property of citizens. their job satisfaction becomes the driving force of their duty. Therefore, we think that some systematic and substantial prevention curriculum to manage their emotional labor is required.

• Journal of the Korean housing association
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• v.25 no.3
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• pp.1-12
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• 2014

Korean traditional house has inherented construction characteristics that contain human requirements with the adaptation to nature's order. As for traditional buildings, there are a lot of facilities like palaces, Buddhist temples, Confucianism architectures, government facilities, etc. Among them, housing construction is not only closely connected to our lives, but also plays an important role to connect our lives from the past to present. The master room in a traditional korean house is responsible for playing a center role of the residential life which implies the traditional values responsible for multi-functions and it is also the sphere of the living space. Therefore, this thesis considers the residential environmental adjustment method and the behaviors centered around the main buildings of Jeonnam Province. And also investigates the main reason for windows and doors formation. From this, we would like to further evaluate the master room life, and the inner space constructions following the spacial and organizational analysis of windows and doors. We would like to analyze the space organization methods, environmental adjustment methods and the usages of traditional buildings. Using the modern interpretation as basis, we would like to use the foundation materials to reflect single family housing plans.

• Journal of Mushroom
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• v.2 no.1
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• pp.1-3
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• 2004

This study were conducted to investigate pin-heading induction and growing temperature of Agaricus brunescens. The temperature for fruit body formation was better at $15^{\circ}C$ than at 18 and $21^{\circ}C$. As the temperature go up to $21^{\circ}C$, the fruit body number was decreased but the fruit body size and weight was increased. Optimal temperature for both pin-heading and growth of Agaricus brunescens was $18^{\circ}C$.

• Journal of Navigation and Port Research
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• v.34 no.10
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• pp.763-768
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• 2010

Today the light of mankind since the dawn of mankind and that they were living "lives" on the huge influence across space is a dynamic energy. Because of this, when all human beings with the light and you can feel more comfortable with a stable mind to the beauty and the pursuit of happiness is to have instincts. In this paper, a fuzzy control system using a combination of external environmental factors, respectively, the conversion of quantitative uncertainty information into the LED lighting is designed to express algorithms, available in indoor circadian control circuit was designed and fabricated LED. Factor in the external environment temperature, humidity, and light intensity values to the controller through the sensor to accept these values and the optimal values for lighting the fuzzy control algorithm is converted into human emotion to feel comfortable to express through the dimming control LED lighting.