• Geophysics and Geophysical Exploration
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• v.12 no.3
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• pp.263-267
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• 2009

Recently intrinsic and scattering quality factor ($\varrho_i^{-1}$ and $\varrho_s^{-1}$) was successfully separated from total quality factor ($\varrho_t^{-1}$) on the seismic data of the Korean Peninsula. From this result, we theoretically calculated the expected coda quality factor ($\varrho_{Cexp}^{-1}$) based on multiple scattering model, and compared with other quality factors such as $\varrho_t^{-1}$, $\varrho_i^{-1}$, $\varrho_s^{-1}$, and observed coda quality factor ($\varrho_c^{-1}$) obtained by single scattering model. While the $\varrho_{Cexp}^{-1}$ values are comparable to the $\varrho_i^{-1}$ values, the $\varrho_c^{-1}$ values are close to the values of $\varrho_t^{-1}$ rather than $\varrho_i^{-1}$ and $\varrho_{Cexp}^{-1}$ except for the 24 Hz frequency. This results suggest that the assumption of uniform scatterer in the Korean Peninsula is unrealistic.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.13-18
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• 1976

1) The variation of the reef knot strength $T_r$ and the trawler knot strength $T_\varrho$ with the angle $\varphi$ between the adjacent bars are given by $$T_r=T_{ro}-k_{r\varphi}$$ and $$T_\varrho=T_{{\varrho}o}+k_{\varrho\varphi}$$ where $T_{ro}$ and $T_{{\varrho}o}$ are values of $T_r$ and $T_\varrho$ at $\varphi=0^{\circ}$ respectively, and $k_r$ and $k_\varrho$ constants decided by the fibre materials of netting twines ($\varphi\;is\;0^{\circ}$ when the knot is pulled lengthwise). 2) The variation of the reef knot strength $T_r'$ and the trawler knot strength $T_\varrho'$ with the angle $\varphi'$ between any one bar and the plane made by the other three bars may be expressed by $$T_r'=T_{ro}{'}\varrho^{-c\varphi'}$$ and $$T_\varrho'=T_{{\varrho}o}{'}\varrho^{-c\varphi'}$$ where $T_{ro}{'}$ and $T_{\varrho}o{'}$ are values of $T_r{'}$ and $T_\varrho{'}$ at $\varphi'=0^{\circ}\;{(\varphi=45^{\circ})}$ respectively, and o is the coefficient of attenuation. 3) Knot strength of knotted netting may be expressed by the expression derived in the preyious paper, disregarding its shape and the direction of tensile loads acting on it.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.47-60
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• 1975

For the calculation of population parameter and estimation of recruitment of a fish population, an application of multiple regression method was used with some statistical inferences. Then, the differences between the calculated values and the true parameters were discussed. In addition, this method criticized by applying it to the statistical data of a population of bigeye tuna, Thunnus obesus of the Indian Ocean. The method was also applied to the available data of a population of Pacific saury, Cololabis saira, to estimate its recuitments. A stock at t year and t+1 year is, $N_{0,\;t+1}=N_{0,\;t}(1-m_t)-C_t+R_{t+1}$ where $N_0$ is the initial number of fish in a given year; C, number o: fish caught; R, number of recruitment; and M, rate of natural mortality. The foregoing equation is $$\phi_{t+1}=\frac{(1-\varrho^{-z}{t+1})Z_t}{(1-\varrho^{-z}t)Z_{t+1}}-\frac{1-\varrho^{-z}t+1}{Z_{t+1}}\phi_t-a'\frac{1-\varrho^{-z}t+1}{Z_{t+1}}C_t+a'\frac{1-\varrho^{-z}t+1}{Z_{t+1}}R_{t+1}......(1)$$ where $\phi$ is CPUE; a', CPUE $(\phi)$ to average stock $(\bar{N})$ in number; Z, total mortality coefficient; and M, natural mortality coefficient. In the equation (1) , the term $(1-\varrho^{-z}t+1)/Z_{t+1}$s almost constant to the variation of effort (X) there fore coefficients $\phi$ and $C_t$, can be calculated, when R is a constant, by applying the method of multiple regression, where $\phi_{t+1}$ is a dependent variable; $\phi_t$ and $C_t$ are independent variables. The values of Mand a' are calculated from the coefficients of $\phi_t$ and $C_t$; and total mortality coefficient (Z), where Z is a'X+M. By substituting M, a', $Z_t$, and $Z_{t+1}$ to the equation (1) recruitment $(R_{t+1})$ can be calculated. In this precess $\phi$ can be substituted by index of stock in number (N'). This operational procedures of the method of multiple regression can be applicable to the data which satisfy the above assumptions, even though the data were collected from any chosen year with similar recruitments, though it were not collected from the consecutive years. Under the condition of varying effort the data with such variation can be treated effectively by this method. The calculated values of M and a' include some deviation from the population parameters. Therefore, the estimated recruitment (R) is a relative value instead of all absolute one. This method of multiple regression is also applicable to the stock density and yield in weight instead of in number. For the data of the bigeye tuna of the Indian Ocean, the values of estimated recruitment (R) calculated from the parameter which is obtained by the present multiple regression method is proportional with an identical fluctuation pattern to the values of those derived from the parameters M and a', which were calculated by Suda (1970) for the same data. Estimated recruitments of Pacific saury of the eastern coast of Korea were calculated by the present multiple regression method. Not only spring recruitment $(1965\~1974)$ but also fall recruitment $(1964\~1973)$ was found to fluctuate in accordance with the fluctuations of stock densities (CPUE) of the same spring and fall, respectively.

• Journal of the Korean Chemical Society
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• v.24 no.1
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• pp.80-85
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• 1980

The free radical copolymeriaztion of N-vinylurea(VU) with vinyl acetate (VAc) was carried out at $60^{\circ}C$ in three solvents. VU-vinyl alcohol(VA) copolymers were prepared by the methanolysis of the VU-VAc copolymers. From the nitrogen content measurements of VU-VA copolymers, the monomer reactivity ratios for the VU-VAc copolymerization and the values of Alfrey-Price's Q and e for VU were determined. These Q and $\varrho$ values obtained in the cases of using methanol and methanol-dioxane as the polymerization solvents are comparable with those found for other monomers which have > NCO-pendent groups. The $\varrho$ value indicates that the urea group of VU is a electron-donating group. The copolymerization parameter of VU shows a strong effect of the solvents. These results are interpreted to be that VU is in equilibrium with its tautomer at the polymerization temperature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.197-201
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• 1975

다랭이 주낚의 양승방식에는 방향의 양승(On-tracing retrieve)방식과 역방향의 양승(Back-tracing retrieve) 방식의 두가지 방식이 있다. 순방향의 양승은 최초에 투승된 주낙끝에서부터 양승하기 시작하여 투승한 순과 같은 순으로 양승하는 것이고 역방향의 양승은 최후에 투승된 주낚끝에서부터 양승하기 시작하며 투승한 순과 반대순으로 양승하는 것이다. 주낚의 조업소요시간을 변갱하지 않고 양승방식만 변갱한다면 주낚의 평균침지시간은 변하지 않고 다만 침지시간의 분포구간만 변한다. 투승작업시간을 $\tau_1$, 투승작업이 끝나고 양승작업을 시작하기까지의 대기시간을 $\tau_2$, 양승작업시간을 $\tau_3$하면 주낚의 침지시간분포범위는 양승방식에 따라 다음과 같이 서로 다르다. $\tau_2$부터 $\tau_1+\tau_2+\tau_3$까지의 범위 역방향으로 양승할 때 $\tau_1+\tau_2$부터 $\tau_2+\tau_3$까지의 범위 임의시의 낚시 어획성능은 $F_0\varrho-^{-zt}$ ($F_0$는 초기어획성능, z는 감소계수, t는 투승후 경과시간)으로 나타낼 수 있고 침지시간 t인 낚시 Hro의 어획미수는 $H_{F_0}\frac{1-\varrho^{-zt}}{z}$로 나타낼 수 있으므로 주낙조업에서 낚시수 $H_G$개 이고 침지시간이 $\tau_\alpha$와 $\tau_\beta$ 범위내에서 분포하면 어획미수는 $C_G$는 다음과 같이 나타낼 수 있다. $$C_G=\frac{H_G}{\tau_\beta-\tau_\alpha}{\cdot}\frac{F_0}{Z}\int^{\tau_\beta}_{\tau_\alpha}(1-\varrho^{-zt})dt$$ $\tau_\alpha,\;\tau_\beta$의 값은 순방향의 양승에 있어서는 $\tau_\alpha=\tau_1+\tau_2,\;\tau_\beta=\tau_2+\tau_3$, 역방향은 양승에 있어서는 $\tau_\alpha=\tau_2,\;\tau_\beta=\tau_1+\tau_2+\tau_3$. 따라서 다랭이 주낚의 어획미수는 그 양승방식에 따라 차가 있고 순방향의 양승으로 더 많은 어획미수를 얻을 수 있다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.43-55
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• 1976

Fertilization and early development of turbo cornutus was studied based on the samples which were collected in Yeosu area. Particular emphasis was paid on induction of artificial spawing, fertilization rate, preembryonic development, the growth of the early larva and larval survival to various salinity. Among the various methods for induction of artificial spawning which have been tested for the present study, drying by exposure to air is the. most efficient, and percentage fertilization rate was $83.8-96.4\%$. The diameter of fertilized eggs was $0.182{\pm}0.0028mm$; and the diameter of egg membrane was $0.245{\pm}0.093mm$. Under the temperature range of $20.6-25.4^{\circ}C$ the larvae hatched out after 11:05-11:15 hours of fertilization. After 3.0-3.5 days of fertilization the planktonic larvae begand to settle, and the settlement terminated within 5 days. During the period of 150 days of early culturing the diameter growth of shell(M) and the diameter of shell aperture(A) was formulated as follows: $$1972\;M=0.33e^{0.02070D}$$ $$A=0.19e^{0.02282D}$$ $$1973\;M=0.32e^{0.02282D}$$ $$A=0.16e^{0.02596D}$$ During the same period of early culturing the relative growth of shell diameter and the diameter of shell aperture was formulated as follows : 1972 A=0.6478 S-0.1575 1973 A=0.5897 S-0.0515 After 11 days of larval hatching $0.02-0.18\%$ of planktonic larvae settled. After 150 days of settlement the survival rate of the early shells was $7.4-21.6\%$. Under the temperature range of $21.0-22.7^{\circ}C$ the optimum salinity range for the development of egg and the planktonic larvae was $30-35\%_{\circ}$.

• Journal of the korean society of oceanography
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• v.33 no.4
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• pp.146-156
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• 1998

Hydrographic data retrieved in the southwestern part of the East Sea in 1992-1993 were analyzed to investigate the probability of southward intrusion of the East Sea Intermediate Water (ESIW) into the Ulleung Basin. The ESIW showed the ranges of 1 to 4$^{\circ}$C in potential temperature, 33.80-34.06 psu in salinity, and 26.9-27.3 kg/m$^3$ in potential density (${\sigma}$$_{\theta}$). The mean depth occupied by the ESIW was 170 m, where the characteristic values of the above three were 2.64$^{\circ}$C , 34.02 psu, and 27.13 kg/m$^3$, respectively. One of the most prominent features of the ESIW was that its salinity changed not only seasonally but also interannually. It was low in summer and high in winter. The salinity within the isopycnal layer of 26.9-27.3 kg/m$^3$ was closely related with the potential vorticity (${\rho}$$_{\theta}^{-1}$ f ${\varrho}$${\rho}_{\theta}$/${\varrho}$z), being in direct proportion to the salinity. This implies that the low-salinity water was thicker than the high-salinity water. The flow path of the ESIW was investigated by tracking the low-salinity or the low-potential vorticity water and by referring to acceleration potential. Careful analysis of the flow path proves that the ESIW intrudes from the north between the Korean coast and Ulleung Island into the Ulleung Basin in summer. Existence of the high-potential vorticity water in the Ulleung Basin is associated with the interruption of the inflow of low-salinity water.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.200-205
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• 1999

In the ferromagnetic phase with electrons for La$_{1-x}$(Ca or Sr)$_x$MnO$_3$, films, a remnant resistivity of the order of 10$^{-8}$ ${\omega}$m is observed up to 100 K and increases exponentially with temperature up to T$_c$ and above one Tesla as a function of magnetic field strength (a positive magnetoresistivity). The phase below T$_c$ is regarded as a polaronic state with a polaronic tunneling conduction. Possible p-wave condensation (or superconductor) with a parabolic density of states and the phase separation are discussed on the basis of the two-fold degeneracy of ${\varrho}_{\delta}$ orbitals.