• Journal of Distribution Research
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• v.17 no.5
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• pp.39-57
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• 2012

The unabated influx of micro businesses has turned the Korean retailing market to a rat race, which causes severe financial distress for micro business owners due to heavy competition. The woes of these micro business owner's are exacerbated by the presence of large scale distributors such as Super Supermarket(SSM) and large discount stores. In summary, the Korean retail market is overburdened an uneconomically viable. Retailing has low barriers to entry which attracts unskilled labor or those with little capital. These start-ups have low opportunity costs since they would make low wages elsewhere in the economy. Thus, these owners are content with relatively low returns on their investment. These 'subsistence ventures' are maintained for economical viability rather than economic growth. These 'subsistence ventures' intensifies competition among small-scale businesses. The presence of large retail corporations also aggravates the situation. The recent stagnation of the economy has worsened the retail market in Korea. The overwhelming competition solidifies the coarse structural system and the prolonged economic sluggishness has increased the risk of insolvency for micro business owners. As the economy continues to stagnate, the imminent risk in retailing market will rise up to surface threatening economic stability. More systematic inflows and outflows of retailers are required in order to redress this structural problem. It has been empirically shown that the self-employment rate is high in Korea compared to other OECD countries. To draw the comparison of self-employment rate by industry, Korea shows high rates among transportation, whole sale, retail, education, lodging, and restaurants. In the case of the transportation and education service sectors, this high rate can be explained by the idiosyncratic nature of Korean culture. In the transportation sector, political policies favor private cap service and private freight carriers. In the education service sector, Koreans put particular emphasis on education that leads to many private institutions that outnumber other OECD countries. For these singular reasons, Korea maintains high micro business, self-employed rates particularly in retailing. A comparable nation is Japan, with its similar social, economic, cultural environment among OECD countries. Unlike Korea, Japan has much lower rates of micro business which continues to decrease. Also Korean retailers are much more destitute than Japanese. The fundamental problem of Korean retailing is the involuntary exit of these 'subsistence ventures,' micro businesses with low margins, in which a small drop in demand can lead to financial difficulties for the owner. This problem will be exacerbated when Korean babyboomers retire and join the micro business ventures. The first priority in order to cope with the severity of oversupply in retailing is to provide better opportunities for the potential self-employers. There should be viable alternatives to subsistent ventures. Strengthening the retirement program, scrutiny of exit process, reconfiguration of policy funds are the recommendations.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.12
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• pp.63-69
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• 1972

There was a concentrated heavy rain resulted in 450mm of precipitation from Aug. 18 and 19, 1972. Almost all the paddy grown in the main plain areas of KimPo, Bu Cheon and Pyong Taek(N. L. $37^{\circ}$00'98'$-37^{\circ}$30'56", Long. $126^{\circ}$45'99"$-127^{\circ}$55'92"E) have been damaged of submergency. The effects of the different degrees of submergency in different growth stages of paddy, on the yield of paddy, rates of fertilization, maturity and degree of heading have been observed, and may be summarized as follows. (1) When the paddy was damaged due to submergency at the heading stage, a) on the basis of normal paddy, the yield of paddy may be expected about 67,57,40,9 and 6% with the submerged periods of 0.5, 1. 0, 2.0, 3.0 and 4.0 days, respectively, and a significant-negative correlation was found between the periods of submergency and the yields. b) As in the yield of paddy, rapid decreases in the rates of fertilizations and maturities of paddy were found as the submerged periods are increased. When the submerged periods are 0.5, 1.0, 2.0, 3.0 and 4.0 days, the corresponding rates of fertilizations and maturities observed are 89 and 88,83 and 78,52 and 40,24 and 19, and 12 and 9%, respectively, showing significant negrative correlations. c) Considerable decreases of the degree of heading were found as the submerged periods are increased. resulted in a significant negative correlation at 1% level between the degree of heading and submerged periods. (2) When the paddy plants were under submergency just before heading, the damage was found to be less than that at heading stage. The yields were 86,82,60,36 and 10%, as compared with the normal yield, with 0.5, 1.0, 2.0, 3.0 and 4.0 days of the submerged periods. (3) When the paddy was under the submergency at the mid-stage of head sprouting, its damage was severer than that of just before heading stage. The yields of paddy under the different submerged periods, 0.5, 1.0, 2.0, 3.0 and 4.0 days, were 79, 64, 34 and 6%, respectively, of the normal yields. normal yields.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.202-208
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• 2006

An experiment was conducted to investigate the effects of three water temperatures (15, 20 and $25^{\circ}C$) in combination with three salinities (0, 15 and 30 psu) on the oxygen consumption rate of juvenile spotted sea bass, Lateolabrax maculatus (mean body weight $5.5{\pm}0.3g$). The oxygen consumption rates of L. maculatus were measured in triplicate for 24 hours using a continuous flow-through respirometer. Water temperature resulted in significant differences in the mean oxygen consumption rate of L. maculatus (p<0.001), but salinity and combinations of salinity and water temperature did not have (p>0.05). The oxygen consumption increased with increasing water temperatures in all experimental salinity regimes (p<001). Mean oxygen consumption rates at 15, 20 and $25^{\circ}C$ ranged 328.8~342.3, 433.9~441.0 and 651.5~659.9 mg $O_2\;kg^{-1}\;h^{-1}$, respectively. $Q_{10}$ values did not vary with salinity, bud varied with water temperature. $Q_{10}$ values ranged 1.63~1.75 between 15 and $20^{\circ}C$, 2.24~2.26 between 20 and $25^{\circ}C$, and 1.92~1.98 over the full temperature range. The energy loss by metabolic cost increased with increasing water temperatures in all experimental salinity regimes (p<0.001) Mean energy loss rates at 15, 20 and $25^{\circ}C$ ranged 224.6~233.8, 296.3~301.2 and $444.9{\sim}450.7kJ\;kg^{-1}\;d^{-1}$, respectively. These data suggest that the culture of juvenile spotted sea bass is possible without energy loss by salinity difference in freshwater as well as seawater after salinity acclimation. Thus, this result has an application for culture management and bioenergetic model for growth of this species.

• KSBB Journal
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• v.21 no.2
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• pp.110-117
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• 2006

During routine maintenance, animal cell lines are commonly cryopreserved in growth medium containing serum with 10% DMSO. But, in case of bioprocess under the serum-free conditions, including cultivation of cell lines and producing of pharmaceuticals, the cryopreservation should be executed without serum to prevent a cross-contamination. This experiments were performed to investigate the effects of the serum-free cryopreservation on the CHO cells. To improve the survival rates of the cryopreserved CHO cells in serum-free condition, first, the effects of permeable and non-permeable additives for substitute serum on cell viability were investigated. The combination of 10% DMSO and 0.03 M raffinose in MEM-${\alpha}$ without serum indicated 76% of cell viability. However, it did not reach the survival rates(more than 95%) of the conventional cryopreservation. In the second, to evaluate the cryopreservative ability of the serum-free medium(SFM) we compared viability of the CHO cells cryopreserved in the SFMs(Sigma C5467, C4726, and C1707, JBI SF486 and PF486), the cryoprotectant(Genenmed CAN-1000) and the MEM-${\alpha}$ with serum. All solution contained 10% DMSO. As a result of the comparison, cryopreserved cells in the SFMs showed over 95% of viability and appeared predominant viability better than cryoprotectant CAN-1000. Finally, we assessed the stability of the CHO cells in the long-term cryopreservation(LTC) using SFM. Every three months, the cryopreserved CHO cells were thawed to estimate the cell viability and the recovery rates. Then, real-time RT-PCR analyzed the inserted CHO DHFR gene. All results for the LTC appeared the same stability as the serum containing cryopreservation. In the conclusion, it could be seen that the LTC in the SFM can substitute for serum using methods in the bioprocess proceeded by CHO cells for more than 18 months.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.1
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• pp.15-20
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• 1994

Lysimeter experiments were conducted to elucidate the behavior of $NO_3-N$ derived from urea applied at different rates and accompanying cations in soils and to further provide fundamental information of rational nitrogen-fertilizer management. Urea was applied at rates of 0, 7, 14, 21, 28 and 35kg N/10a to sandy loam pakced into PVC cylindrical lysimeter(vol. : $0.187m^2$, area $0.43m^2$). Leachates from the lysimeter with or without grass grown were collected periodically and analyzed for $NO_3$ and cations. Grass growth and yield responses to N fertilization were also examined. Dry matter yield and nitrogen uptake increased with the urea application rate. The amount of leachate from the lysimeter was negatively correlated with urea application ratesl($r=-0.95^{**}$). The nitrate leaching loss with grass grown was 230 g N/10a at the maximum rate of 35kg N/10a, but the highest leaching loss was observed as 1,607 g N/10a from the bare plot. Increase in urea application rates decreased significantly leaching losses of Ca, Mg, K and Na(>0.01). The highest leaching loss from the bare plot was observed for Ca but only 6.5% of exchangeable form and 14.0% for K from the grass plot respectively. Equivalent ratio of cations to nitrate leached were 3.2 % for the bare plot and the ratio for the grass plot increased with the urea application rate, ranging from 18.6 to 32.7%.

• Korean Journal of Organic Agriculture
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• v.22 no.4
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• pp.667-682
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• 2014

The effects of liquid pig manure (LM) on the yield and quality of rice as well as soil chemical properties were determined in the field of sandy loam soil under the different fertilizer management. Treatments consisted of 100%, 130% and 160% N application rates of liquid manure as calculated on the basis of the recommended rate of nitrogen (9 kg N/10a) for rice cultivation. Chemical fertilizer (CF) was used as control. Concentrations of T-N and T-P in paddy water were measured by 5-day intervals up to 20days after application. LM treatments significantly increased T-N concentrations in paddy water proportionally with increasing rates of LM (13.2 to 25.7 mg/L). Similarly Total-P content in paddy water was increased right after LM applications but was well below the quality standard of wastewater and manure. Plant height and tillers in 100% and 130% N LM treatments were lower than those in CF control. In the 160% LM treatment, however, plant height and numbers of tillers were higher than those in the CF control. Yields in 100% LM and 160% LM plots were decreased by 3 and 5%, respectively, as compared with 422 kg per 10a in the CF plot. Rice protein contents were similar between 100% LM and CF control (about 6.8%) but it was increased to 7.2% and 7.7% in 130% LM and 160% LM treatments, respectively. Toyo-taste value in the 100% LM treatment was higher than in CF control plot. The proportions of perfect grain of the brown rice were lower in 130% LM and 160% LM treatments than that in CF control. Soil organic matter content, heavy metal and exchangeable cations were highest in the 160% LM plot. Thus considering yield and quality of rice and heavy metals contents in soil, 130% N basal application of liquid manure can be recommended for rice cultivation in this experiment.

• Journal of Plant Biotechnology
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• v.50
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• pp.248-254
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• 2023

This study was conducted to establish an efficient plant regeneration system in 'Dayu', a Korean variety of Perilla frutescens developed for seed oil production, in conjunction with the previously studied variety 'Namcheon'. The healthiest callus was formed on the hypocotyl explants cultured on a medium containing 0.1 mg/L NAA and 0.5 mg/L BA, outperforming the leaf and cotyledon samples. In both dark and long-day conditions, Dayu consistently exhibited significantly higher shoot regeneration rates compared with Namcheon. The highest shoot regeneration rates in Dayu were observed from the hypocotyl explants cultured on 0.1 mg/L NAA and 0.5 mg/L BA media, with shoot regeneration rates of 84.4% and 86.7% under dark and long-day conditions, respectively. Various combinations of plant growth regulators were tested to establish the optimal shoot regeneration conditions for Dayu hypocotyl explants. The results demonstrated that the highest shoot regeneration rate (90%) was achieved when 0.5 mg/L of BA was added to the medium without NAA. Among the regenerated shoots, 70.5% were normal plants, while 19.3% were abnormal. The addition of NAA or an increase in its concentration led to a higher occurrence of abnormal plants. After the regenerated shoots were transferred to 1/2 MS medium, roots were observed within 10-15 days. By day 30, they had developed into complete plants. The results obtained from the regeneration experiments with the perilla variety Dayu can valuably inform molecular breeding reliant on transformation techniques such as genome-editing and genetic modification technology.

• Journal of Wetlands Research
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• v.20 no.2
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• pp.155-160
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• 2018

We investigated to know the growth patterns of Aedes albopictus larva at the four different temperature conditions. Each of 120 individuals was placed into a $20m{\ell}$ vial and 12 sets (a set of 10 vials) were separated into 12 water tanks ($17{\times}24{\times}18cm^3$). Each water tank was composed of 3 the $1^{st}$ instar, 3 the $2^{nd}$ instar, 2 the $3^{rd}$ instar, and 2 the $4^{th}$ instar. Three sets of water tanks were placed under the four different incubator temperatures ($17^{\circ}C$, $21^{\circ}C$, $24^{\circ}C$, $28^{\circ}C$). We found that the eclosion rates were $20.00{\pm}5.77%$ at $21^{\circ}C$ and $3.33{\pm}3.33%$ at other temperatures. For the mosquito larva mortality rate, $1^{st}$ instar was $19.24{\pm}3.65%$, $2^{nd}$ instar was $16.48{\pm}3.25%$, $3^{rd}$ instar was $23.54{\pm}5.06%$, and $4^{th}$ instar was $40.74{\pm}7.08%$. The lowest mortality rate in growth stages according to temperature was $13.33{\pm}6.67%$ at $17^{\circ}C$ in $1^{st}$ instar larva, $7.41{\pm}7.41%$ at $21^{\circ}C$ at $2^{nd}$ instar larva, $10.74{\pm}6.43%$ at $24^{\circ}C$ in $3^{rd}$ instar larva, and $20.37{\pm}5.46%$ at $28^{\circ}C$ in $4^{th}$ instar larva. The survival period of mosquitoes in underwater were $26.33{\pm}0.67days$ at $17^{\circ}C$, $23.33{\pm}1.33days$ at $21^{\circ}C$, $20.00{\pm}2.52days$ at $24^{\circ}C$, and $11.67{\pm}1.20days$ at $28^{\circ}C$. From our results the most effective temperature to the normal growth of mosquito larva was $21^{\circ}C$, and the highest mortality rate was shown at the $4^{th}$ instar stage of larva growth. Our results would provide the basic data for the mosquito larva's growth pattern.

• Journal of the Korean Society of School Health
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• v.7 no.1
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• pp.57-71
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• 1994

I investigated actual conditions of smoking of teenagers who were randomly chosen middle and high school students. 1. Juvenile smoking 1) Parents' opinions of juvenile smoking Most parents do not want their children to smoke after growth : 88.6% of fathers (middle school students: 88.9%, high school students: 88.4%) and 95.1% of mothers (middle school students: 93.4%, high school students :95.5%). 2) Teenagers' opinions of smoking after growth The rate of students who will smoke after growth is 10.8% (middle school students: 12.0%, high school students: 9.9%): students in agricultural areas show the higher rate than those in cities. 3) Parents' opinions of their children's smoking now 1.5% of fathers want their children to smoke now (middle school students: 1.3%, high school students: 1.6%) and 1.1% of mothers do (middle school students: 0.6%, high school students: 1.5%). This shows that most parents do not want their children to smoke now. 4) Students' opinions of their friends' smoking now Students who want their friends smoke now cover 7.8% (middle school students: 7.1%, high school students: 8.4%). This rates are higher than those of parents shown in (3). And more high school students and more girl students gave the positive reponse than middle school boy and girl students, respectively. 5) Students' views of smoking "Look like an adult" covers the rate of 4.0% (boy: 7.8%, girl:3.6%) 6.7% of middle school students have this view, while 3.7% of high school students have. 16.1% of students had an experience of smoking during the last one year (boy: 29.9%, girl: 8.6%): this shows that the rate of the boy students is more than 3 times greater than that of the girl students and high students who experienced smoking last year covers 20.2%, while middle school students shows 10.9%. 6) Actual conditions of students' smoking The present rate of students' smoking is 22.4% (boy:38.3%, girl:13.8%): the rate of boy students is greater than that of girl students. Students who smoke more than pack of cigarettes a day cover 8.2% (boy: 17.5%, girl: 3.2%): 5.2% of middle school students (boy:11.4%, girl: 2.1%) smoke more than one pack while 10.7% of high school students do (boy:21.5%, girl: 4.2%). This shows that the rate of boy students' smoking is greater than that of girl students' smoking. 7) The rate of smoking of students' parents 75.4% of fathers (city: 74.5%, agricultural area:75.9%) smoke: and more than a half (62.4%) smoke more than a pack cigarettes a day. On the other hand, the rate of smoking mothers is 5.2%(city: 4.3%, agricultural area: 7.3%): the rate is higher in agricultural areas. 8) Opinions of smoking population in the future 61.4% of students answered that smoking population will increase, while 27.0% have the opinion that smoking population will decrease. 2. Opinions of the effects of smoking on health 1) Have you heard that smokers are likely to suffer from tuberclosis? 78.3% of students said yes (boy: 80.8%, girl: 76.4%): it is shown that the rate of boys is greater than that of girls. 2) Have you heard that smokers are likely to get out of endurance? 76.6% of students (boy: 69.3%, girl: 49.7%) answered yes: it is shown that the rate of boys is greater than that of girls. 3) Have you heard that heart-beats get fast when one smokes? 32.5% of students (boy: 35.5%, girl: 30.9%) answered yes: 32.2% in cities(boy: 33.0%, girl: 31.8%) and 33.5% in agricultural areas(boy: 41.8%, girl: 28.8%): and 28.7% middle students and 35.5% of high school students answered yes. 4) Have you heard that smokers are likely to have heart-diseases? 35.1% of students (boy: 34.0%, girl: 34.1%) answered yes: 35.3% in cities (boy: 37.2%, girl: 34.2%) and 36.7% in agricultural areas (boy: 39.0%, girl: 33.9%): 34.8% of middle school students and 35.4% of high school students. 5) Have you heard that smokers are likely to have a lung cancer? 91.4% of students (boy: 93.2%, girl: 89.9%) answered yes: 90.35% in cities and 94.2% in agricultural areas. 6) Have you heard that the life of smokers gets shorter? 94.3% of students (boy:94.6%, girl: 92.2%) answered yes. 7) Have you heard that pregnant smokers will deliver a baby with low birth weight? 29.6% of students (boy: 29.8%, girl: 29.4%) answered yes: the rates of boys and girls almost the same. 8) Have you heard that one feels calm when one smokes? 80.1% of students (boy: 81.8%, girl: 79.2%) answered yes: boys and girls showed almost the same rate. 3. Preventive measures Smoking people continued to increase all over the world because smoking not only mitigated emotional uneasiness such as loneliness, nervousness and so on, but also could be very helpful from the social perspective. This was so because they did not consider harmful effects of smoking on health, and victims. However, because any -one can have physical disorders caused by smoking, people should always keep in mind the following preventive measures. 1) Doctors or teachers should set an example of giving up smoking. Informing patients or students of harmful effects of smoking to persuade their family and relatives not to smoke. 2) Through mass media like newspapers, periodicals or broadcasting, to make people know harmful effects of smoking and not smoke. 3) To prohibit selling teenagers cigarette by law. 4) To prohibit smoking in public places like work places, offices, lecture rooms, recreation rooms, buses, trains and so on. 5) To decrease the rate of life insurance for non-smokers as in foreign countries and to give a warming of the harmful effects on cigarette packets or ads.

• Korean journal of applied entomology
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• v.26 no.1 s.70
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• pp.13-23
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• 1987

This study was conducted to know the effects of temperature conditions on the growth and oviposition of the brown planthopper(BPH), Nilaparvata lugens $St{\aa}l$. Results obtained were to predict the timing of the BPH control by measuring population dynamics of the BPH in response to temperature fluctuations upon migration of the insects in paddy fields. Developmental and ovipositional rates under constant and alternating temperature conditions were observed in a plant growth cabinet. Hatchabilities of eggs of the BPH were the highest at $25^{\circ}C$ and were decreased below or above the optimum temperature. Egg periods were the shortest at $27.5^{\circ}C$ and prolonged with decreasing temperature, but retarded at higher temperature above $30^{\circ}C$. Adult emergence rates were the highest at $27.5^{\circ}C$ and reduced with decreasing temperature, and no adult emerged at $32.5^{\circ}C$ and $35^{\circ}C$. Developmental period of nymph was the shortest at both $27.5^{\circ}C$ and $30^{\circ}C$, but extended with decreasing temperature. Female longevity was increased with decreasing temperature and the male longevity was the shortest at $27.5^{\circ}C$. Preoviposition period was the shortest at $32.5^{\circ}C$, but prolonged with decreasing temperature. It was about 6.5 times longer at $17.5^{\circ}C$ than that at $32.5^{\circ}C$. Number of eggs oviposited per female was the greatest at $25^{\circ}C$, but decreased at the temperature below or above the optimum. Under the same total effective day-degrees, hatchabilty at the alternating temperature was about 10% higher than that at the constant temperature but egg period at the alternating temperature was nearly identical as that at the constant. Under the $22^{\circ}C$ condition, emergence rate was about 8% higher at the alternating temperature than that at the constant, however, at the $28^{\circ}C$, the rate was about 8% higher at the constant than that at the alternating. Nymphal period was about $4{\sim}6$ days longer at the alternating temperature than that at the constant. Under the same total effective day-degrees in adult stage, both longevity and oviposition period were longer at alternating temperature than those at the constant. Number of eggs oviposited per female was also higher at the alternating. Longevities of females reared under $28^{\circ}C$ of constant temperature was the longest no matter what temperatures they were exposed after the emergence. This result seems to be indicating that female longevity is greatly influenced by the temperature to which they were exposed durings immature stages. Preoviposition period was affected by the temperature exposed during the nympal and adult stage whereas the number of eggs oviposited was affected by the temperature during the adult stage only. Based on the results from this study, the developmental threshold temperatures seem to be $14.12^{\circ}C$ for eggs, $14.76^{\circ}C$ for nymphs, $9.62^{\circ}C$ for adults, and $15.95^{\circ}C$ for preoviposition period. Estimated values of the total effective temperature for completing each stage were 141.25 day-degrees for eggs, 167.83 day-degrees for nymphs, 349.64 day-degrees for adults, and 58.60 day-degrees for preoviposition.