• 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 Ceramic Society
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• v.41 no.6
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• pp.444-449
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• 2004

The microwave dielectric properties of low temperature sintered BaO-Nd$_2$O$_3$-TiO$_2$ (here after BNT) with a Pb-based glass-ceramics were studied in order to investigate their applicability to Low Temperature Co-fired Ceramics (LTCC) for fabrication of multilayered Radio Frequency (RF) passive components module. The BNT ceramics, with 5∼30 wt% of PbO-TiO$_2$-A1$_2$O$_3$-SiO$_2$ based glass-ceramics, were sintered at 105$0^{\circ}C$, which is lower than 130$0^{\circ}C$, sintering temperature of pure BNT ceramics. With increasing the amount of the glass-ceramics, sintering rate of the ceramics become activated due to the softening of glass, resulting in low-temperature densification. BaO-Nd$_2$O$_3$-TiO$_2$ microwave ceramics with 20 wt% glass-ceramics exhibit sintered relative densities over 95% and dielectric constant of 72, quality factor of 1500, and temperature coefficient of frequency of +22 ppm/$^{\circ}C$. This enhanced dielectric properties are attributed to mainly the presence of crystalline phases PbTiO$_3$ within the Pb-based glass.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.423-429
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• 2001

Prediction of the variation in annual biomass was conducted for the white croaker. Argyrosomus argentatus in Korean waters using leslie Matrix, based upon fishery data for the past 21 years and biological data, We used density-independent and density-dependent Leslie Matrix models. Similar parameters were estimated from two models except that the density-dependent model was influenced by the density effect variable, q(i,t), The eigenvalue of the white croaker population for the $1984\~1995$ period was estimated to be 0.8, indicating a declining pattern of the population. The survival rate of 0-th year class was calculated to be 0.00005. Based on the schedule of the age-specific survival rate and fecundity, the future biomass and catch was predicted for various levels of fishing mortalities (F), If F was set at 0.252/yr ($F_{35x}$) or 0.368/yr ($F_{0.1}$), the biomass and catch increased, and if F was set at 0.922 ($F_{current}$), the biomass and catch decreased, The fishing mortality at equilibrium was estimated to be 0.7/yr. Finally, the management strategy of the white croaker was discussed.

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.598-603
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• 2002

The effects of alumine borosilicate glass composition on the densification and the microwave properties of (M $g_{0.93}$C $a_{0.07}$)Ti $O_3$ ceramics were studied. As the amount of glass increase, the density of ceramics increases and grain growth enhances. When 20 ~30 wt% of glass added, it was densified to over 95% of (M $g_{0.93}$C $a_{0.07}$)Ti $O_3$ theoretical density. (M $g_{0.93}$C $a_{0.07}$)Ti $O_3$ ceramic sintered at 95$0^{\circ}C$ exhibits dielectric constants of 15~16, quality factor of 8000 and temperature coefficient of resonant frequency of -45 ppm/$^{\circ}C$ by adding 20 wt% alumine borosilicate glass.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.172-177
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• 2003

Effect of glass addition on the low-temperature sintering and microwave dielectric properties of $BaTi_4O_9$-based ceramics were studied to develop the materials for the functional substrate of low-temperature co-fired ceramics. When 10 wt% of glass was added, sufficient densification was obtained and the relative density more than 98% was reached at the sintering temperature of$875{\circ}C$. The microwave dielectric properties were k=32, Q＊f=9000 GHz, ${ au}_f$=10 ppm/${\circ}C$. As the amount of glass increased, phase decompositions from $BaTi_4O_9;to;BaTi_5O_{11};and;Ba_4Ti_{13}O_{30}$ was observed.

• Journal of Bio-Environment Control
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• v.17 no.2
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• pp.83-89
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• 2008

A wind tunnel test was conducted at Protected Horticulture Experiment Station of National Horticultural Research Institute in Busan to find the aerodynamic resistance and quadratic resistance coefficient of chrysanthemum in greenhouse. The internal plants of the CFD model has been designed as a porous media because of the complexity of its physical shapes. Then the aerodynamic resistance value should be input for analyzing CFD model that crop is considered while the value varies by crops. In this study, the aerodynamic resistance value of chrysanthemum canopy was preliminarily found through wind tunnel test. The static pressure at windward increased as wind velocity and planting density increased. The static pressure at leeward decreased as wind velocity increased but was not significantly affected by planting density. The difference of static pressure between windward and leeward increased as wind velocity and planting density increased. The aerodynamic resistance value of chrysanthemum canopy was found to be 0.22 which will be used later as the input data of Fluent CFD model. When the planting distances were $9{\times}9\;cm$, $11{\times}11\;cm$, and $13{\times}13\;cm$, the quadratic resistance coefficients of porous media were found to be 2.22, 1.81, and 1.07, respectively. These values will be used later as the input data of CFX CFD model.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.108-108
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• 2000

급증하는 무선통신 정보수요는 특히, 고주파대역 (300NHz-300GHz)에서 사용되는 공진기, 필터, 발진기 등과 같은 소자의 품질향상을 요구하고 있다. 고주파용 유전체 중 ZrTiO4 는 $\alpha$-PbO2 계열의 사방정구조를 갖고 있는 유전체로서 높은 유전율 ($\varepsilon$=40)과 높은 품질계수 (Q=1/tan$\delta$=4700 at 7GHz)를 갖고 있고, Sn 첨가시 0ppm/$^{\circ}C$의 공진주파수 온도계수를 얻을 수 있다고 보고되어 있다. 본 연구에서는 약 110$0^{\circ}C$ 이상에서 안정한 상으로 존재하는 ZrTiO4를 저온에서 증착하여 준안정한 상태로 결정화되게 한후, 유전손실 (tan$\delta$)과 유전율($\varepsilon$)을 측정하였다. 또한 증착온도와 열처리과정에 따른 박막의 us형 (Strain) 정도의 변화를 X-선 회절결과로부터 분석하였으며 이를 측정된 유전특성 값과 비교하였다. ZrTiO4 박막은 DC magnetron reactive sputter로 Zr과 Ti 타겟으로부터 high phosphorous doped Si (100) 기판위에 증착하였다. 압력은 4mTorr로 유지하고 박막의 화학양론적 조성비를 맞추기 위해 각 타겟에 가해지는 power는 Zr/Ti=500W/650W로 고정하고, 반응가스의 비율을 Ar/O2=17sccm/3.5sccm으로 유지하여 박막내에 인입되는 산소량을 제어하였다. 증착 직후와 열처리 후의 박막특성을 비교하기 위해 증착온도를 상온에서부터 $600^{\circ}C$까지 변호시키고 증착후 각각의 시편을 80$0^{\circ}C$ 산소분위기에서 2시간동안 열처리하여 시편을 준비하였다. 박막의 상형성 여부와 결정성변화는 $ heta$-2$\theta$X-선 회절법을 사용하여 조사하였고, EPMA를 이용하여 박막의 조성을 확인하였다. 유전특성의 측정을 위해 백금 상부전극을 증착한 후, impedance analyzer를 이용하여 100kHz 영역에서의 유전손실을 측정하고, 측정된 정전용량과 박막의 두께로부터 유전율을 계산하였다. ZrTiO4 박막은 증착온도 20$0^{\circ}C$ 이상에서 결정성을 보이기 시작했으며, 열처리 이후에는 상온에서 비정질이었던 시편이 $650^{\circ}C$ 이상의 온도에서 결정화되기 시작하였다. 증착온도에 따라 유전손실은 0.038에서 0.017 정도로 감소하는 경향을 나타냈으며, 각각 열처리에 의해서 0.034, 0.005 정도로 다시 감소하였다. 박막의 유전율은 약 35 정도의 값을 나타내었으며 X-선 회절 data로부터 분석한 박막의 변형은 증온도에 따라 7.2%에서 0.04%로 감소하였고 이 이경향은 유전손실은 감소경향과 일치하였다.

• Journal of the Korea Concrete Institute
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• v.24 no.2
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• pp.137-145
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• 2012

Strength model for blasted furnace slag mortar blended with sodium was investigated in this study. The main parameters of AAS (alkali activated slag) mortar were dosage of alkali activator, water to binder ratio (W/B), and aggregate to binder ratio (A/B). For evaluating the property related to the dosage of alkali activator, sodium carbonate ($Na_2CO_3$) of 4~8% was added to 4% dosage of sodium hydroxide (NaOH). W/B and A/B was varied 0.45~0.60 and 2.05~2.85, respectively. An alkali quality coefficient combining the amounts of main compositions of source materials and sodium oxide ($Na_2O$) in sodium hydroxide and sodium carbonate is proposed to assess the compressive strength of alkali activated mortars. Test results clearly showed that the compressive strength development of alkali-activated mortars were significantly dependent on the proposed alkali quality coefficient. Compressive strength development of AAS mortars were also estimated using the formula specified in the previous study, which was calibrated using the collected database. Predictions from the simplified equations showed good agreements with the test results.

• Journal of Korean Society of Forest Science
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• v.112 no.1
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• pp.23-31
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• 2023

Predicting forest productivity is essential to evaluate sustainable forest management or to enhance forest ecosystem services. Ordinary least squares (OLS) and partial least squares (PLS) regression models were used to develop predictive models for forest productivity (site index) from the site characteristics and soil profile, along with soil physical and chemical properties, of 112 Quercus mongolica stands. The adjusted coefficients of determination (adjusted R²) in the regression models were higher for the site characteristics and soil profile of B horizon (R²=0.32) and of A horizon (R²=0.29) than for the soil physical and chemical properties of B horizon (R²=0.21) and A horizon (R²=0.09). The PLS models (R²=0.20-0.32) were better predictors of site index than the OLS models (R²=0.09-0.31). These results suggest that the regression models for Q. mongolica can be applied to predict the forest productivity, but new variables may need to be developed to enhance the explanatory power of regression models.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.103-111
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• 2008

Soils naturally contain grains of different minerals which may be dissolved under chemical or physical processes. The dissolution leads changes in microstructure of particulate media, such as an increase in local void or permeability, which affects the strength and deformation of soils. This study focuses on the small strain stiffness characteristics of vanishing mixtures, which consist of sand and salt particles at different volume fractions. Experiments are carried out in a conventional oedometer cell (Ko-loading) integrated with bender elements for the measurement of shear waves. Dissolutions of particles are implemented by saturating the mixtures at various confining stresses. Axial deformation and shear waves are recorded after each loading stage and during dissolution process. Experimental results show that after dissolution, the vertical strain and the void ratio increase, while the shear wave velocity and small strain shear modulus decrease. The decrease of the velocity results from the void ratio increase and particle contact decrease. The process monitoring during dissolution of the particles shows that the vertical strain dramatically increases at the beginning of the saturation process and converges after vanishing process finishes, and that the shear wave velocity decreases at the beginning and increases due to the particle reorientation. Specimens prepared by sand and salt particles are proved to be able to provide a valuable insight in macro structural behaviors of the vanishings mixtures.