• 한국양식학회지
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• 제8권3호
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• pp.183-193
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• 1995

청틸라피아 (Oreochromis aureus)의 자어에 0, 1, 10, 60 ppm의 $17\alpha-methyltestosterone$(MT)을 30 일간 사료에 섞어 먹인 후 다음 57 일간을 0 ppm을 먹인 그룹은 다시 세그룹으로 나누어 0 ppm MT (0-0), 10 ppm MT (0-10), 및 60 ppm MT (0-60)을 먹였고, 60 ppm 을 먹인 그룹은 다시 3 그룹으로 나누어 0 ppm MT (60-0), 10 ppm MT (60-10), 및 60 ppm MT (60-60)을 먹였으며, 초기 30 일간 1 ppm과 10 ppm MT를 먹인 것은 계속해서 1과 10 ppm을 먹여서 체조성과 생식소 중량지수에 미치는 영향을 조사하였다. 초기 30 일간 어체의 조단백과 조지방은 MT 농도와 역상관 관계를 보였고, 수분 함량은 순상관 관계를 보였다. 후기 57 일간에 먹인 MT는 초기 30 일간 먹인 MT 보다도 숫컷의 체조성에 더 큰 영향을 미쳤다. 사료 중의 MT는 초기 30 일간이나 후기 57 일간 모두 숫컷의 생식소 중량지수에 나쁜 영향을 보인 반면에, 암컷의 경우에는 후기 57 일간에 사료 중의 MT 양이 생식소 중량지수에 나쁜 영향을 나타내었다.

• 한국발생생물학회지:발생과생식
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• 제17권2호
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• pp.79-85
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• 2013

To understand the sex reversal characteristics in the longtooth grouper (Epinephelus bruneus), this study examined the sex reversal and artificial masculinization of wild caught E. bruneus reared in indoor rearing tank after a 17${\alpha}$-methyltestosterone injection. To domesticate a broodstock, 64 wild caught E. bruneus, between 47.0 to 110.0 cm in total length and from 1.5 to 21.4 kg in body weight, were reared in indoor rearing tank (4.0 to 5.0 m wide, and 2.5 to 3.0 m depth) for four years. Seven specimens showed sex reversal from female to male during indoor rearing condition, whose total length and body weights were from 63.0 to 99.0 cm and from 4.4 to 13.2 kg, respectively. After inducing artificial masculinization in 14 female E. bruneus with a 17${\alpha}$-methyltestosterone (2.0 mg/kg BW) implants for 3 years, spermiation occurred in 9 specimens (total length: 54.0 to 68.0 cm, body weight: 2.3 to 4.3 kg). Among the female to male sex reversals, two specimens returned back to being female, whose body weights were 2.8 kg (initially 2.6 kg) and 2.7 kg (initially 2.3 kg). Therefore, this study suggested that E. bruneus (> 3.0 kg) was more effective in masculinizing by 17${\alpha}$-methyltestosterone implants.

• 비파괴검사학회지
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• 제28권1호
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• pp.59-63
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• 2008

Time reversal (TR) of nondispersive body waves has been used in many applications including ultrasonic NDE. However, the study of the TR method for Lamb waves on thin structures is not well established. In this paper, the full reconstruction of the input signal is investigated for dispersive Lamb waves by introducing a time reversal operator based on the Mindlin plate theory. A broadband and a narrowband input waveform are employed to reconstruct the $A_0$ mode of Lamb wave propagations. Due to the frequency dependence of the TR process of Lamb waves, different frequency components of the broadband excitation are scaled differently during the time reversal process and the original input signal cannot be fully restored. This is the primary reason for using a narrowband excitation to enhance the flaw detectability.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.452-457
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• 2000

The object of this study is to develop a reliable FEM simulation technique for the analysis of can making process using PAM-STAMP software. The processes consist of doming and necking in addition to drawing, redrawing. After body making process, this study analyzed the stability for internal pressure by simulating buckling test. Through these technique, we estimated the dome reversal pressure of steel D&I Can for various can profile and process conditions. From this study, we found the cause and mechanism of wrinkling during necking process. This mechanism is largely affected by can wall thickness and the clearance between knock out punch and necking die. The dome reversal pressure improves with increasing dome depth. These results validate the usefulness of the developed simulation technique for the analysis of body making process and optimization of the dome profile.

• 한국양식학회지
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• 제8권4호
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• pp.271-283
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• 1995

청틸라피아(Oreochromis aureus)의 자어에 0, 1, 10, 60 ppm의 $17\alpha-Methyltestosterone$ (MT)을 30 일간 성 전환기 사료에 섞어 먹인 후 다음 39 일간(성전환 후기) 0 ppm 을 먹인 그룹은 다시 세 그룹으로 나누어 0 ppm MT (0-0), 10 ppm MT (0-10), 및 60 ppm MT (0-60)을 먹였고, 60 ppm을 먹인 그룹은 다시 3 그룹으로 나누어 0 ppm MT (60-0), 10 ppm MT (60-10), 및 60 ppm MT (60-60)을 먹였으며, 초기 30 일간 1 ppm과 10 ppm MT를 먹인 것은 계속해서 각각 1 ppm과 10ppm을 먹여서 월동시킨 다음 10개월 후인 이듬해 9월 말경에 체조성과 생식소 중량 지수에 미치는 영향을 조사하였다. 암수 모두에서 2 년째의 성장에 대한 MT의 잔류 효과는 없었다. MT를 먹인 그룹의 성장은 전혀 먹이지 않은 대조군보다 통계적으로 유의성있게 좋았는데(P<0.05) 그 이유는 대조군에 있는 암컷의 성장 지연으로 인한 전체 평균 중량의 감소 때문이었다 사료 중의 MT 함량이 증가하는데 따라 수컷의 조지방 함량은 증가하여 순상관 관계의 잔류 효과를 나타내었으나 체 수분 함량은 오히려 MT가 증가함에 따라 감소하는 역상관 관계의 결과가 나타났다. 암컷에서는 사료 중 MT가 증가함에 따라 체 수분함량이 감소하는 역상관 관계의 잔류 효과를 보였다. 성전환 후기의 암수 모두의 생식소 중량 지수에 역상관 관계를 나타내었고, 성전환기에 사료에 섞어 섭취된 MT는 2 년째의 수컷의 생식소 중량 지수에 잔류 효과를 나타내어 MT 농도가 증가하는데 따라 생식소 중량 지수가 감소하는 역상관 관계를 나타내었다. .그러나 생식소 발달이 완료된 성전환 후기에 먹인 MT는 암수 모두에서 생식소 중량 지수에 잔류 영향을 보이지 않았다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.471-476
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• 2001

The main object of this study is to develop a reliable FEM simulation technique for stability test using ABAQUS software and to clarify the effect of base profile of a steel D&I(drawn and ironed) can on the dome reversal pressure. For the can after body making simulation, two kind of stability test, dome buckle test and axial crush test are performed. The factors studied in the base profile on the dome reversal pressure are the base diameter, the rim radius, the dome shoulder radius, the dome radius and the dome depth. Within the limits before the occurrence of normal snap-through buckling of dome, the dome reversal pressure is improved by decreasing the base diameter, increasing the dome depth or increasing the dome shoulder depth.

• 비파괴검사학회지
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• 제28권1호
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• pp.54-58
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• 2008

Time reversal (TR) of body waves in fluids and isotropic solids has been used in many applications including ultrasonic NDE. However, the study of the TR method for anisotropic materials is not well established. In this paper, the full reconstruction of the input signal is investigated for anisotropic media using an analytical formulation, called a modular Gaussian beam (MGB) model. The time reversal operation of this model in the frequency domain is done by taking the complex conjugate of the Gaussian amplitude and phase received at the TR mirror position. A narrowband reference signal having a particular frequency and number of cycles is then multiplied and the whole signal is inverse Fourier transformed. The original input signal is seen to be fully restored by the TR process of MGB model and this model can be more generalized to simulate the spatial and temporal focusing effects due to TR process in anisotropic materials.

• 한국양식학회지
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• 제9권1호
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• pp.19-23
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• 1996

Hormonal induction of sex reversal was examined by using sex steroid hormones in serranid fish, Epinephelus septemfasciatus. Young fish were collected from the coastal area of Cheju Island, and reared for 2 years before fish were used for the experiments. Without any hormonal treatment, gonads of fish ($1,000\~2,800$ g in body weight) were occupied by oocytes of the perinucleolus stage and bundles of protogonial cells in the area of germinal epithelium. When the induction of sex reversal was attempted by daily oral administration of $17\alpha$-methyltestosterone (0.5 mg/kg fish) for 90 days, active spermatogenesis was induced, and spermatogonia and spermatocytes and spermatids were appeared in all gonads we examined. However, after daily, oral treatment of $17\beta$-estradiol (0.5 mg/kg fish) to. 50 days with the following injection of human chorionic gonadotrophin ($1,000\~1,500$ IU/kg fish) mature oocytes were not induced in fish gonad.

• 자원환경지질
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• 제14권3호
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• pp.111-122
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• 1981

This study is a model analysis for an effective application of the geophysical prospecting to the investigation of geological structures or useful resources, and the purpose of it is to research a property of the electrical resistivity prospecting, especially by using a Three-Point electrode array method. In using the Three-Point electrode array method, it is theoretically assumed to choose the infinite for a distance between the two current electrodes, however it is impossible in applying to the practical field prospecting. Therefore this study was conducted for determination and presentation of a minimum appropriate distance between the two current electrodes by making a study on prospecting effect in the variation of distance between both the electrodes. In case that the ratios of the distance between the two current electrodes to that between the two potential electrodes are respectively chosen for 40, 400, 5,000, the experimental data of this study showed that the minimum appropriate distance between the two current electrodes is forty times as much as that between two potential electrodes. In order to make clear a problem about prospecting depth which is essential to the data processing, it had been chosen equally to the distance between two potential electrodes. As a result of it, it was shown that the anomaly is appeared along the position of an assumed ore body. Consequently it was found out that the prospecting depth of the Three-Point electrode array method is the same as the distance between the two potential electrodes. From the model experiment on the sheeting ore body(or linear structure) of horizontal, dipping of $30^{\circ}$, $60^{\circ}$ and vertical on the basis of above experimental condition, it was found out that the position and dip of assumed ore body could be inferred from the aspects of the equiresistivity curve. In consequence of performing out the simultaneous Normal and Reversal electrode movement, it was shown that the electrode movement of the Reversal forms the anomaly more clearly than that of Normal when the sheeting ore body is situated obliquely, therefore it could be ascertained that the electrode movement have to be performed simultaneously in the manner of Normal and Reversal. It was also exhibited that the aspect of the equiresistivity curve forms symmetrically when an assumed ore body (or linear structure) is situated horizontally or vertically, that is, symmetrically, and moreover that the aspect of the equiresistivity curve forms unsymmetrically when an assumed ore body (or linear structure) is situated obliquely. On the basis of these experimental analysis it is thought that it can be inferred from the aspect of equiresistivity curve whether an assumed ore body is obliquely situated or not.

• Preventive Nutrition and Food Science
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• 제9권3호
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• pp.253-258
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• 2004

Stress is a global menace exacerbated by the advancement of industrialization. Failure of stress management is to a breakdown of the psychological and physiological protection mechanisms against stress. The aim of present study was to investigate the anti-stress potential of ginseng against immobilization stress. Male Sprague-Dawley rats (n=24) were divided into three groups; (i) control, (ii) immobilization stress (2hr daily, for 2 weeks), and (iii) immobilization stress (2 hr daily, for 2 weeks) plus oral administration of ginseng (200 mg/kg BW Id). Immobilization stress resulted in a significant inhibition of body weight gain by 45 % and a significant decrease in the tissue weights of thymus and spleen (p < 0.05). The concentrations of blood GOT and GPT were significantly increased in the immobilization-stressed group compared to the control group (p < 0.05). There were no differences in the blood cholesterol levels among groups. Ginseng administration in the immobilization-stressed group tended to reverse the lack of body weight gain and food intake, though not significantly. The ginseng-administered group showed a significant reversal in the stress-induced effect on spleen and thymus weight, increasing the tissue weights by 16% and 20%, respectively, compared to immobilization-stressed group (p<0.05). The plasma corticosterone level was significantly increased in the stressed group by 39 % compared to the control group (p<0.05), but ginseng administration significantly reversed the stress-induced increase in plasma corticosterone by 15 % compared to the immobilization-stressed group. The present study suggests that the anti-stress effect of ginseng is mediated by normalization of stress-induced changes in the circulating hormones and a reversal of tissue weight loss, thereby returning the body to normal homeostasis.