• Journal of Nutrition and Health
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• v.40 no.8
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• pp.708-718
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• 2007

The purpose of this project was to evaluate whether vitamin E supplementation could improve the antioxidant status and lymphocyte DNA damage in Korean postmenopausal women. This was double blinded, placebo-controlled trial. Thirty-five subject were randomized to receive either placebo 400 mg/capsule or natural $\alpha$-tocopherol 400 IU/capsule, 2 times a day for 6 weeks. We measured plasma vitamin C, $\alpha$-tocopherol, $\gamma$-tocopherol, $\alpha$-carotenoid, $\beta$-carotenoid, lycopene concentration and tail length, %DNA in tail, tail moment in lymphocyte DNA damage index. Vitamin E supplementation group had significantly increased plasma vitamin C(p<0.05), $\alpha$-tocopherol(p<0.000), whereas $\gamma$-tocopherol(p<0.000) and tail length(p<0.05) were significantly decreased. However, placebo supplementation group also had significantly increased plasma vitamin C(p<0.05). In conclusion, our study shows that vitamin E supplementation to Korean postmenopausal women may partially improve antioxidant status and lymphocyte DNA damage.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.39-42
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• 2008

In the case of the general helicopter among rotorcraft, length of the rotor blade for thrust-generation is longer than that of fuselage and tail rotor is required in order to compensate moment of the fuselage. For those reasons, enough space for take-off and landing should be secured and an accessibility for building is low. Also, the accidents caused by tail rotor occur frequently. However, the case of counter-rotating has merits that tail rotor is unnecessary as well as length of the rotor blade can be shortened but has a weakness that the weight of body is increased. In the present study, aerodynamic force measurement on single rotor system equipped with NACA0012 airfoil, which has aspect ratio of 6 and chord length of 35.5 mm, was carried out. And measurement was conducted with blade which has a half size of the former blade by using single motor counter-rotating. Aerodynamic force measurement was acquired by using 6-component balances and coefficients of thrust and power were derived along the pitch angle varying from 0$^{\circ}$ to 90$^{\circ}$ with the increment of 10$^{\circ}$. Those aerodynamic force data will be utilized for the design and production of brand-new counter-rotating rotor blade system which has same thrust with single blade system and provides a good accessibility to building by reducing its blade length.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2868-2872
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• 2007

In this study, a passive control using a boat-tail device is conducted for a three-dimensional car model in ground proximity. We consider various boat-tails and investigate the mechanism of drag reduction by them. By varying the length and slant angle of boat-tail, we obtain drag reductions up to 40%. From the oil-surface flow visualization and hot-wire measurement, the drag reduction by the boat-tail is characterized by the shear-layer instability and reattachment on the boat-tail, forming a small separation bubble at the upstream part of boat-tail surface, resulting in the delay of main separation and drag reduction. At high slant angles, the flow fully separates and drag is nearly same as that of no control.

• Korean Journal of Veterinary Research
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• v.27 no.1
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• pp.1-7
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• 1987

The present studies were designed to investigate the morphology and stainability of the chicken spermatozoa. Semen samples were collected by abdominal massage from 10 cocks of Arbor, Acres strain (egg breed) and 10 cocks of white Cornish strain (meat breed). The semen samples were diluted with Sarker's solution and were washed. Some of the semen smear slides were stained with seven differential stain methods and was compared with one another by light microscope. In addition to the staining already compared, the length of heads, middle pieces and tails of 400 spermatozoa of two chicken breed was measured with micrometer. The results obtained from these, studies were as follows: 1. Eosin stain appeared to give good results than hematoxylin, pre-treated protease and eosin or hematoxylin stain, pre-treated protease and hematoxylin-eosin stain, carbol-fuchsin, stain and Giemsa 9 technique in differential staining of spermatozoal three portions and pre-treated protease and eosin stain appeared as good staining methods for middle piece of spermatozoa. 2. The average length of chicken spermatozoa was $90.4{\pm}4.0{\mu}m$, and the average length of the head, middle piece and tail of spermatozoa was $13.0{\pm}0.5{\mu}m$, $3.8{\pm}0.2{\mu}m$ and $73.6{\pm}3.8{\mu}m$ lesoectively. 3. The average length of spermatozoa of Arbor Acres strain was $89.2{\pm}5.0{\mu}m$ and the average length of the head, middle piece and tail of spermatozoa was $12.9{\pm}0.5{\mu}m$, $3.8{\pm}0.2{\mu}m$ and $72.5{\pm}4.7{\mu}m$ respectively. The average length of spermatozoa of with Cornish was $91.6{\pm}3.0{\mu}m$ and the average length of the head, middle piece and tail of spermatozoa was $13.1{\pm}0.5{\mu}m$, $3.8{\pm}0.2{\mu}m$ and $74.7{\pm}2.8{\mu}m$ respectively.

• The Korean Journal of Zoology
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• v.39 no.4
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• pp.437-446
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• 1996

The courtship and fighting behaviors and the sexual dimorphism of the salamander Hynohius leechil were studied. The parameters, snout vent length, body length (from snout to tail tip), and proportion of snout vent length to body size were larger in the female than the male. Five physical parameter in males were significantly correlated with one another, body length, snout vent length, head width, tail vent length, and tall depth, while all, except tail depth, were significantly correlated in females. Sexual behavior of H. leechIl involved external fertilization and consisted of three stages, identifying the female, aifrading the female, and insemination. The identification stage consisted of a positive advance by the male toward the female and display of snout contact. The male attracted the female with chin rubbing, tail undulation, smelling, and digging displays. The insemination process consisted of four phases, amplex, separating egg sacs from the female's cloacal, fertilizing eggs, and post fertilization. liighting behaviors were quite simple. The attacking male would generally bite the opposite male's upper chin or hind limbs and then shakes his head two or three times. The bitten male, which in most cases was of a dissimilar body size, quicidy escaped from the attacking male. After fighting, winning male usually displayed rapid tail undulation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.3
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• pp.205-213
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• 2021

Two specimens of Hemitrygon izuensis (395.8-471.5 mm in disc width), belonging to the family Dasyatidae (Myliobatiformes), were collected from the waters off north-eastern Jeju-do Island in June 2016 and Pohang in August 2019. This species was characterized by having no spots on dorsal side of disc, white ventral tail fold and short preorbital snout length (15.6-18.3% of disc width). This species is similar to H. akajei and H. sinensis reported in Korea, but differs in small denticles on mid-line of dorsal surface of disc (absent in H. izuensis vs. present in H. akajei and H. sinensis), the length of ventral tail fold (28.1-31.0% in H. izuensis vs. 48.0-48.6% in H. akajei vs. 45.0% in H. sinensis), color of ventral tail fold (white in H. izuensis vs. black in H. akajei and H. sinensis) and small tubercles on the posterior part of tail (absent in H. izuensis vs. present in H. akajei and H. sinensis). We suggest a Korean name for H. izuensis as "I-ju-gal-saeg-ga-o-li" following Kim et al. (2019).

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.625-636
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• 2019

Recently, research on projectiles with wings for precision guidance is actively underway. In this study, we analyzed how the tail fins attached to the projectile affect the base drag. Aerodynamic analysis was performed with RANS(Reynolds Averaged Navier-Stokes) equations using FLUENT, a commercial CFD(Computational Fluid Dynamics) code. Through the aerodynamic analysis, the base drag characteristics of the projectile by parameters (number, length, thickness, position, shape of tail fin) were investigated. The results of this study are expected to be applicable to aerodynamic design of tail fins mounted on projectiles.

• Journal of the Korean Wood Science and Technology
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• v.15 no.3
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• pp.1-13
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• 1987

This study was carried out to investigate the variations of dimension and exterior shape of vessel elements, morphology of spiral thickening and ray-vessel pit in korean diffuse-porous woods (56 species, 18 families), The tangential pore diameter and vessel element length was increased, whereas the pore number per unit area($1mm^2$) was decreased from pith outwards. The tangential pore diameter was decreased but the length of vessel element was not changed from earlywood to latewood within an annual ring. However, the dimensional variations of vessel element was not able to be recognized among relative positions in peripheral variation. The exterior shape of vessel element could be classified into four types; Type 1 is without tail, Type 2 with ligulate tail, Type 3 with broad taper tail and Type 4 with the very short length between perforations. The distribution frequency of Type 2 and 3 was relatively high in comparision with the others. According to the prominence, distribution position and branched shape, the spiral thickenings could be divided into five types. The spiral thickenings occurred 52% in the species observed. Thus it was doubtful to consider the simple presence of spiral thickening as diagnostic index in diffuse-porous woods. The morphology of ray-vessel pit could be grouped as reticulate, scalariform, oval, linear and coalescent type. Most of species examined showed oval and linear type.

• The Korean Journal of Malacology
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• v.24 no.1
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• pp.1-10
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• 2008

Spermatogenesis and the reproductive cycle in male Spisula sachalinensis were investigated by cytological and histological observations. The morphology of the spermatozoon has a primitive type and is similar to those of other bivalves in that it contains a short midpiece with four mitochondria surrounding the centrioles. But spermatozoon of this species has not axial rod and satellite body in the midpiece. The morphologies of the sperm nucleus type and the acrosome shape of this species have a globe-shape type and modified cap-like shape, respectively. The spermatozoon is approximately $40-45{\mu}m$ in length including the sperm nucleus length (about $1.35{\mu}m$), acrosome length (about $1.50{\mu}m$) and tail flagellum. The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9+2 structure. The spawning period of these species lasts from June to July, and the main spawning occurs in July when seawater temperatures are greater than $20^{\circ}C$. The male reproductive cycle of this species can be categorized into five successive stages: early active stage (October to January), late active stage (February to April), ripe stage (April to June), partially spawned stage (June and July), and spent/inactive stage (August to September).

• The Korean Journal of Malacology
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• v.22 no.2
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• pp.115-124
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• 2006

Gonad index, spermatogenesis and the reproductive cycle of Meretrix petechialis were investigated by cytological, histological observations. Monthly changes in the gonad index coincides the gonadal development. The morphology of the spermatozoon had a primitive type and is similar to that of other bivalves having a short mid-piece with five to six mitochondria surrounding the centrioles. The morphology of the sperm nucleus type and the acrosome shape of this species were cylindrical type and cap-like shape, respectively. The spermatozoon was approximately 40-45 ${\mu}m$ in length including the sperm nucleus length (about 1.50 ${\mu}m$), acrosome length (0.60 ${\mu}m$) and tail flagellum. The axoneme of the tail flagellum consisted of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail showed 9 + 2 microtubular arrangement. The spawning period was from June to September and the main spawning occurred from July to August when seawater temperatures were higher than $20^{\circ}C$. The reproductive cycle of this species could be categorized into five successive stages: early active stage (February to March), late active stage (February to May), ripe stage (April to July), partially spawned stage (June to September), and spent/inactive stage (September to February).