• Korea journal of population studies
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• v.25 no.1
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• pp.257-289
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• 2002

In this study we analyse how the tobacco prices have an effect on the national health. The level of tobacco price will fluctuate its consumers demand and eventually affect the national health status. We estimate tobacco consumption function as well as households'demand system in which tobacco and health expenditure functions are included. Demand elasticities are estimated and evaluated in order to find future policies to improve the national health by controlling the national tobacco consumption There are two econometric approaches app1ied in this study. The lent tobacco demand analysis method is mm tobacco consumption function model. Using national indices of tobacco price, tobacco consumption and other related variables, tobacco consumption function is estimated. The other is micro demand system analysis by using Korean urban households expenditure data during the period of 1991 to 1999. The own price elasticity which is estimated from national tobacco demand per capita is -0.19 for all people and -0.176 for the adults over 18, which means 100% price increase will cause decease of tobacco demand at 19% and 17.6% per each The cross vice elasticity which is estimated between tobacco and health expenditure of urban households demand system is -0.2328, which implies 100% of tobacco price increase will decrease 23.28% of health expenditure. The low price elasticities imply that tobacco price increase will increase total tobacco sales volume. 100% of tobacco price increase will bring about 79% increase of total tobacco sales volume according to our scenario. Korea's tobacco demand is negatively responsive to fluctuations in its price. The health expenditure is also negatively relatedto the tobacco price fluctuation. These empirical outputs could be utilized as the basis of government's tax policy to control national tobacco consumption in the future.

• 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.

• Korean journal of applied entomology
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• v.51 no.2
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• pp.99-109
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• 2012

Seasonal fluctuations of Riptortus pedestris were investigated in four regions including two sites each at Mt. Yangseong (Munui-myeon, Cheongwon-gun), O-chang (Cheongwon-gun), and Jujung-dong (Cheongju) using aggression pheromone traps from April to November in 2010 and 2011. Aggression pheromone and aggression pheromone + soybean traps were set at all investigated sites, and the Mt. Yangseong A and B sites were investigated at a farmland (80 m, asl) and forest (200 and 300 m). The population density of R. pedestris was high in mid June, mid August, and late October in 2010 and in early May, mid June, mid September, and early October in 2011 with trivoltine. O-chang and Jujung-dong populations, which were distinguished in farmlands and forests, were highest from June to August in the farmland and in September in the forest. Similar numbers of R. pedestris were capture in the farmlands and the forest in June-August, September-November, respectively. From the results of the four regions, more R. pedestris adults were captured in the aggression pheromone + soybean trap than that in the pheromone trap. To investigate the migration route by altitude, 500 R. pedestris adults marked with fluorescent paint were released and re-caught insects were counted in traps after 10 and 20 days. The pattern of the re-caught R. pedestris indicated migration from the forest to farmlands during April-June. These results suggest that the insects did not migrate in August because food was plentiful in the forest at 200 m, but they moved to the forest during October due to the scarcity of food and for overwintering. The R. pedestris seasonal fluctuations in 2011 were affected heavily by the environment, particularly rain precipitation.

• KDI Journal of Economic Policy
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• v.12 no.3
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• pp.3-26
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• 1990

Encouraged by the investment in the rice paddy, the introduction of new varieties (Tong-Il), and the price support program, there has been great success in increasing rice production. Meanwhile, the demand for rice has decreased rapidly as per capita income continues to rise. Rice self-sufficiency has been attained, and a new over-supply problem is emerging. Moreover, the Uruguay Round Agricultural Negotiation would prohibit government price support for agricultural products. In October the Korean government decides the government purchase amount and support price, which works as the price guideline. All interested parties exert political efforts to influence the decision. The continued increase of the government purchase price of rice due to political pressure pushed the government purchase price above the market wholesale price in 1988. Also, the farmers preferred to sell to the government than to the wholesaler. This has discouraged the market mechanism, and the government is to take over the three functions of the market mechanism: stockpiling, seasonal price fluctuation adjustment, and circulation. Another big increase may cause the government purchase price to rise above the consumer price, which might lead to arbitrage opportunities for the farmers and suffocate the market mechanism. However, the current political situations limits the options for the Korean government. This paper argues that a supply control policy will reduce the social cost resulting from the high level of producer price support, and it proposes several second best policies: First, the production of new varieties should be reduced rapidly. Second, the old rice in the government warehouse should be auctioned or disposed of in order to reduce the government handling and management costs. Third, the acreage diversion program should be launched in order to control rice paddy acreage. Fourth, a social welfare program in rural areas should be introduced, since the share of population over 60 is increasing rapidly. Fifth, instead of the price support which is forbidden by the Uruguay Round, Korea should restructure the agricultural industry by developing new crops, by enhancing productivity and by improving the agricultural infrastructure.

• Journal of Food Hygiene and Safety
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• v.16 no.4
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• pp.324-332
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• 2001

Foods constitute a large portion of heavy metal exposure toward general population and attract a deep concern with respect to assuring human health. This study summarized published data in Korea on the content, and dietary intake of heavy metals and assessed their risk potential in comparison with foreign data. An analysis for the yearly fluctuation of metal contents including arsenic, cadmium, mercury and lead by flood group (marine fishes, coastal shellfishes, freshwater fishes, cereal grains) exhibited a decreasing trend from the 1970s to the 1990s. When compared with domestic standards of heavy metals, their mean contents were below the limit and their maximum values seldom exceeded the limit. The data on the dietary intake of heavy metals by Koreans showed a decreasing trend from the 1980s to the 1990s. The average intakes offs and Hg were 6∼8% and those of Cd and Pb were 50∼80% of PTWI(provisional tolerable weekly intake), all of which were below the tolerance. As the extreme intakes of these metals may exceed the PTWI, a careful assessment for them may be necessary. Dietary intakes of Cd, Hg and Pb by Koreans lie in the mid-level among countries cited in the GEMS/Food monitoring data. As fishery foods are suspecious of contamination with Hg, Cd and As, and floods in general are with Pb, it is necessary to establish legal limits for these metals and monitor any progress of their contamination. Furthermore, overall assessment of exposure to heavy metals from all sources including floods, air, drinking water and occupation should be made in order to confirm the dietary risk factors and to assure the safety of food resources.

• The Korean Journal of Mycology
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• v.13 no.4
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• pp.195-201
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• 1985

Numbers of total bacteria and fungal propagules were highly populated in the soil of diseased plot in Gumsan, whereas numbers of actinomycetes were high in the soil of healthy plot in Goesan. In microbial fluctuation of different soil conditions four weeks after amended with various plant materials, bacteria were decreased in the soil amended with various plant materials as compared with non-amended soil except for Goesan. On the contrary, numbers of fungal propagules were increased amended with onion and potato stalk in two soils at different conditions, and also the propagules were enhanced in the soil amended with various plant materials in general. Higher numbers of bacteria and fungal propagules were observed in the diseased replanted plot in general, but germination rate of fungal spores relatively reversed against the microbial population. Alternaria panax was not affected much in their germination by natural soil condition, while Fusarium spp. were affected in their germination by natural soil. Natural soil showed a fungistatic effect against four fungal spores.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.620-626
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• 1997

Annual biomasses of the hairtail, Trichiurus lepturus, were estimated from the biomass-based cohort analysis (Zhang, 1987), using data of annual catch in weight at age during $1970\~1988$ in Korean waters. Annual biomass of the hairtail was peaked at about 240,000 mt in 1975, and thereafter declined with a slight fluctuation. Adult biomass showed a peak in 1978 with about 55,000 mt. However, it has continuously decreased untill 1980 to the level of 9,000 mt and remained at this level till 1988. Age compositions of the hairtail in the 1980s differed greatly from those in the 1970s. The proportions of older hairtail (>4 years) were very low in the 1980s and even the biomasses of young hairtail $(1\~3\;years)$ were at a low evel in the 1980s compared with the level in 1970s. The 1973 and 1974 year classes appeared to be relatively dominant. The mean value of instantaneous rate of fishing mortality (F) in the 1980s was significantly different from that of the 1910s (P<0.05). Recruitment of the hairtail exhibited a similar trend with stock biomass until 1974, indicating the density-dependent Ricker curve.

• The Korean Journal of Soil Zoology
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• v.5 no.2
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• pp.47-62
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• 2000

This study investigated the effect of soil animals at forest fire area, and it carried out the mountain located at Jundae Ri, Houeng-chen Myen, Ha-dong Gun, Kyoung-Nam Province, southern part of Korea, where burned out about 50 hectars on April 11, 1997. Vegetation of the examined area absolutely dominated with the pines of 7-14 cm in diameter and 20 to 30 years old and the rest were covered with mixed forest with a shrub such as the oak (Quereus mongolia Fisch, Quereus variabilis BI, Quereus dentana Thunb), snowbell(Styrax japonica, S, et, z), lacquer tree (Rhus trichocarpa Mig), azalea (Rhododendron mucronulatum Turcz), etc. And there were simple area organized as a herbaceous plant, and the burnt area was poor experimental sites, where litter layer and herbaceous plant disappeard due to fire, and the unburnt area was rich in surface plant, dead leaves, twigs, etc. But the ground cover vegetations were poor in the unburnt area. The distribution of each animal groups, the seasonal fluctuation in population density, the biomass of meso$.$macroarthropods and the relationship between soil animal and some environmental factors were investigated and analyzed at each experimental area. The result are summarized as follow: 1. Identificated 257,087 individuals of soil microarthropods were classified into 7 classes and 24 orders of Arachinida, Insecta, Chilopoda, Symphyla, Diplopoda, Isopoda and Oligochaeta., and identified 8,006 individuals of the total meso$.$macroarthropods were classified into 7 classes and 20 orders of Arachinida, Insecta, Chilopoda, Symphyla, Diplopoda, Isopoda and Oligochaeta. 2. Among the total soil microarthropods, Arachinida formed 70.9%, followed by Insecta for 28.4% and among the total meso$.$macroarthropod , Insecta formed 57.6%, followed by Chilopoda for 23.8%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.6
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• pp.529-535
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• 1984

This study aims at obtaining the basic data for the development of pen shell culture at Yoja Bay, the southwest coast of Korea. The authors dealt with the annual gonadal changes of the pen shell, Atrina pectinata japonica, to find out the gametogenesis, reproductive cycle and spawning season, and to investigate the fluctuation in the larval occurence in Yoja Bay. From July 1983 to June 1984, an average of 20 individuals as specimens were monthly collected by commercial fishing dredge near Manwol island located at the mouth of Yoja Bay. The degree of gonadal development was determined by the histological observations as resting spent stage, early developmental stage, after developmental stage, early spawning stage, after spawning stage and degenerative stage. According to these degrees of gonadal development, annual reproductive cycle of the pen shell population was determined. From July to August, the gonads were changed through degenerative into resting stage and, in September and October, they became entirely empty gonads. From November they showed the first sign of gametogenesis developing very slowly. Nevertheless, the developing gametes did not increase in number probably owing to a phagocytic phenomenon by phagocytes which appeared in the gonad during this stage. Some individuals started spawning in April and in May majarity of individuals were in spawning stage. In June, majority of the individuals showed signs of degenerative stage. Therefore, the authors came to a conclusion that the pen shells in Yoja Bay spawn chiefly in May. And this is also supported by the result of the survey on the planktonic occurrences of the pen shell larvae. Namely, there were no larvae at all in April, only a few in May and many in June by vertical water sampling.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.50-55
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• 2000

Occurrence, Injury aspects and control effect of some chemicals were investigated on tomato in plastic house from 1997 to 1998. Adults trapped by yellow sticky trap and sweeping net were increased from late May abruptly. Survey of population densities by yellow sticky trap was more clear than sweeping net. Damaged leaves were found out all the year round in continuous cropping fields and rate of damaged leaves was below 20% in early April and increased gradually up to 80% level after late May. Otherwise, damaged leaves were appeared from 6 weeks after transplanting in first growing field and then damaged leaves was 80% level in spring culture. In autumn culture, rate of damaged leaves was maintained 80% level from transplanting to harvesting date regardless of cultivation years. Number of adults was trapped from late May and peak was late June but mature larva was $6{\sim}8$ individuals in spring culture. In autumn culture, adult and larval densities was maintained high for 3 weeks after transplanting but begun to decrease from 4 weeks(early September). Chlorfenapyr EC, cyromazine WP and abamectin EC could suppress larval populations of Liriomyza trifolii effectively.