• Korean Journal of Ecology and Environment
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• v.45 no.2
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• pp.158-173
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• 2012

The objectives of this study were to analyze the longitudinal gradient and temporal variations of water quality in Daecheong Reservoir in relation to the major inflowing streams from the watershed, during 2001~2010. For the study, we selected 7 main-stream sites of the reservoir along the main axis of the reservoir, from the headwater to the dam and 8 tributary streams. In-reservoir nutrients of TN and TP showed longitudinal declines from the headwater to the dam, which results in a distinct zonation of the riverine ($R_z$, M1~M3), transition ($T_z$, M4~M6), and lacustrine zone ($L_z$, M7) in water quality, as shown in other foreign reservoirs. Chlorophyll-a (CHL) and BOD as an indicator of organic matter, were maximum in the $T_z$. Concentration of total phosphorus (TP) was the highest (8.52 $mg\;L^{-1}$) on March in the $R_z$, and was the highest (165 ${\mu}g\;L^{-1}$) in the $L_z$ on July. Values of TN was the maximum (377 ${\mu}g\;L^{-1}$) on August in the $R_z$, and was the highest (3.76 $mg\;L^{-1}$) in the $L_z$ on August. Ionic dilution was evident during September~October, after the monsoon rain. The mean ratios of TN : TP, as an indicator of limiting factor, were 88, which indicates that nitrogen is a surplus for phytoplankton growth in this system. Nutrient analysis of inflowing streams showed that major nutrient sources were headwater streams of T1~T2 and Ockcheon-Stream of T5, and the most influential inflowing stream to the reservoir was T5, which is located in the mid-reservoir, and is directly influenced by the waste-water treatment plants. The key parameters, influenced by the monsoon rain, were TP and suspended solids (SS). Empirical models of trophic variables indicated that variations of CHL in the $R_z$ ($R^2$=0.044, p=0.264) and $T_z$ ($R^2$=0.126, p=0.054) were not accounted by TN, but were significant (p=0.032) in the $L_z$. The variation of the log-transformed $I_r$-CHL was not accounted ($R^2$=0.258, p=0.110) by $I_w$-TN of inflowing streams, but was determined ($R^2$=0.567, p=0.005) by $I_w$-TP of inflowing streams. In other words, TP inputs from the inflowing streams were the major determinants on the in-reservoir phytoplankton growth. Regression analysis of TN : TP suggested that the ratio was determined by P, rather than N. Overall, our data suggest that TP and suspended solids, during the summer flood period, should be reduced from the eutrophication control and P-input from Ockcheon-Stream should be controlled for water quality improvement.

• Korean Journal of Ecology and Environment
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• v.37 no.2 s.107
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• pp.180-192
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• 2004

This study was carried out to assess the seasonal variation of water quality and the effect of pollutant loading from watershed in a shallow eutrophic reservoir (Shingu reservoir) from November 2002 to February 2004, Stable thermocline which was greater than $1^{\circ}C$ per meter of the water depth formed in May, and low DO concentration (< 2 mg $O_2\;L^{-1}$) was observed in the hypolimnion from May to September, 2003. The ratio of euphotic depth to mixing depth ($Z_{eu}/Z_{m}$) ranged 0.2 ${\sim}$ 1.1, and the depth of the mixed layer exceeded that of the photic layer during study period, except for May when $Z_{eu}$ and $Z_{m}$ were 4 and 4.3 m, respectively. Most of total nitrogen, ranged 1.1 ${\sim}$ 4.5 ${\mu}g\;N\;L^{-1}$, accounted for inorganic nitrogen (Avg, 58.7%), and sharp increase of $NH_3$-N Hand $NO_3$-N was evident during the spring season. TP concentration in the water column ranged 43.9 ${\sim}$ 126.5 ${\mu}g\;P\;L^{-1}$, and the most of TP in the water column accounted for POP (Avg. 80%). During the study period, DIP concentration in the water column was &;lt 10 ${\mu}g\;P\;L^{-1}$ except for July and August when DIP concentration in the hypolimnion was 22.3 and 56.7 ${\mu}g\;P\;L^{-1}$, respectively. Increase of Chl. a concentration observed in July (99 ${\mu}g\;L^{-1}$) and November 2003 (109 ${\mu}g\;L^{-1}$) when P loading through two inflows was high, and showed close relationship with TP concentration (r = 0.55, P< 0.008, n = 22). Mean Chl. a concentration ranged from 13.5 to 84.5 mg $L^{-1}$ in the water column, and the lowest and highest concentration was observed in February 2004 (13.5 ${\pm}$ 1.0 ${\mu}g\;L^{-1}$) and November 2003 (84.5 ${\pm}$29.0 ${\mu}g\;L^{-1}$), respectively. TP concentration in inflow water increased with discharge (r = 0.69, P< 0.001), 40.5% of annual total P loading introduced in 25 July when there was heavy rainfall. Annual total P loading from watershed was 159.0 kg P $yr^{-1}$, and that of DIP loading was 126.3 kg P $yr^{-1}$ (77.7% of TP loading. The loading of TN (5.0ton yr-1) was 30 times higher than that of TP loading (159.0 kg P yr-1), and the 78% of TN was in the form of non-organic nitrogen, 3.9 ton $yr^{-1}$ in mass. P loading in Shingu reservoir was 1.6 g ${\cdot}$ $m^{-2}$ ${\cdot}$ $yr^{-1}$, which passed the excessive critical loading of Vollenweider-OECD critical loading model. The results of this study indicated that P loading from watershed was the major factor to cause eutrophication and temporal variation of water quality in Shingu reservoir Decrease by 71% in TP loading (159 kg $yr^{-1}$) is necessary for the improvement of mesotrophic level. The management of sediment where tine anaerobic condition was evident in summer, thus, the possibility of P release that can be utilized by existing algae, may also be considered.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.1
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• pp.1-13
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• 2006

A field survey on the spatio-temporal distribution characteristics and origins of organic matter in surface sediments was carried out monthly at six stations in Gamak Bay, South Korea from April 2000 to March 2002. The range of ignition loss(IL) was $4.6{\sim}11.6%(7.1{\pm}1.6%)$, while chemical oxygen demand(CODs) ranged from $12.25{\sim}99.26mgO_2/g-dry(30.98{\pm}19.09mgO_2/g-dry)$, acid volatile sulfide(AVS) went from no detection(ND)${\sim}10.29mgS/g-dry(1.02{\pm}0.58mgS/g-dry)$, and phaeopigment was $6.84{\sim}116.18{\mu}g/g-dry(23.72{\pm}21.16{\mu}g/g-dry)$. The ranges of particulate organic carbon(POC) and particulate organic nitrogen(PON) were $5.45{\sim}23.24 mgC/g-dty(10.34{\pm}4.40C\;mgC/g-dry)$ and $0.71{\sim}2.99mgN/g-dry(1.37{\pm}0.58mgN/g-dry)$, respectively. Water content was in the range of $43.1{\sim}77.6%(55.8{\pm}5.6%)$, and mud content(silt+clay) was higher than 95% at all stations. The spatial distribution of organic matter in surface sediments was greatly divided between the northwestern, central and eastern areas, southern entrance area from the distribution characteristic of their organic matters. The concentrations of almost all items were greater at the northwestern and southern entrance area than at the other areas in Gamak Bay. In particular, sedimentary pollution was very serious at the northwestern area, because the area had an excessive supply of organic matter due to aquaculture activity and the inflow of sewage from the land. These materials stayed longer because of the topographical characteristics of such as basin and the anoxic conditions in the bottom seawater environment caused by thermocline in the summer. The tendency of temporal change was most prominently in the period of high-water temperatures than low-water ones at the northwestern and southern entrance areas. On the other hand, the central and eastern areas did not show a regular trend for changing the concentrations of each item but mainly showed a higher tendency during the low-water temperatures. This was observed for all but AVS concentrations which were higher during the period of high-water temperature at all stations. Especially, the central and eastern areas showed a large temporal increase of AVS concentration during those periods of high-water temperature where the concentration of CODs was in excess of $20mgO_2/g-dry$. The results show that the organic matters in surface sediments in Gamak Bay actually originated from autochthonous organic matters with eight or less in average C/N ratio including the organic matters generated by the use of ocean, rather than terrigenous organic matters. However, the formation of autochthonous organic matter was mainly derived from detritus than living phytoplankton, indicated the results of the POC/phaeopigment ratio. In addition, the CODs/IL ratio results demonstrate that the detritus was the product of artificial activities such as dregs feeding and fecal pellets of farm organisms caused by aquaculture activities rather than the dynamic of natural ocean activities.

• Journal of Korean Society of Forest Science
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• v.36 no.1
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• pp.9-25
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• 1977

As a successive work of the variation studies of natural Pinus densiflora stands, some characteristics of individual trees of the three natural populations selected from the Kwang-won Province, the middle-east part of Korean peninsula, as shown in the location map, were investigated. And the statiscal differences between individuals within population, and between populations were analysed. Twenty trees from each population were selected for this study purpose. Doing this, those trees lagged in growth, usually showing poorer form, were eliminated. The results obtained are summarized as follows: 1. Though the average population ages had the ranage between 50 and 63, the growth of height or diameter was similar. Population No.9 is, however, considered to have better tree forms at glance. Population No.8 showed the heighest value not only in the clear-stem-length ratio. 0.53 but also in the crown-index 0.91. The higher value can be result from those trees having long lateral branches and relatively short crown height, meaning undesirable crown shape. In regard to the fine branchedness and the acuteness of branching angle, the population No.9. is considered to be a better one, whereas there was almost no difference in crown height among populations. 2. Checking the frequency distributions of the ratio of the clear-stem-height to the total height and the crown-indices, some difference between populations are considered. These might be attributed to the previous way of stand mangement which alters the density. 3. In the serration density, the average number of 54 per 1cm needle length, the significant differences exist between individual trees within population but not between populations. A few trees which extremly high serration density were observed. As in serration, so tendencies were in the number of stomata row and resin duct. 4. The population 8 had the resin duct index value of 0.074 as the highest which was twice or triple of the other ones. 5. The patterns of increasing process of the average 10-year-ring-segment were not similar till the 30 years of age, but beyond this, the tendency lines were aggregated. 6. Regading the average summer wood ratio, no diffrence between populations, but in the ranges, i.e. 23 to 30 in population No.8. and 16 to 36 in population No.9., with regad to the specific gravity of wood, there were hardly observed any difference between populations even in the ranges values. As the increase of tree ages, the increase of specific gravity was followed but the increasing patterns were not similar between populations. 7. No significant differences between populations in the average tracheid length and the range were detected. However, the length was increased according to the age increase. The increasing pattern was same between populations.

• Asian Journal of Turfgrass Science
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• v.18 no.4
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• pp.179-191
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• 2004

This study was conducted to find out the effect of sodding and seeding time and rate of seed mixtures on the establishment of cool-season turfgrasses by evaluating the turf coverage rates for two years. In fall planting, the required establishment period of full coverage($100\%$) was 1.5 months with a rolled turf sodding(Kentucky bluegrass $100\%$, Kentucky bluegrass $80\%$+perennial ryegrass $20\%$). The $100\%$ turf establishment was achieved in 7 months with Perennial ryegrass $100\%$, and 7.5 months by seeding with Kentucky bluegrass $100\%$(KB 100), Kentucky bluegrass $80\%$+perennial ryegrass $20\%$(KB80+PR20), Kentucky bluegrass $70\%$+perennial ryegrass $30\%$(KB70+PR30). In spring planting, the establishment periods far sod with KB 100 or KB80+PR20 were taken one month. However, in the case of seeding, the establishment periods were 3 months, 3.5 months, 3.5 months and 4 months with PR100, KB80+PR20, KB70+PR30, and KB 100, respectively Comparing the turf establishment vigor between fall and spring planting, the vigor was higher In spring planting than in fall planting in both sodding and . seeding. In the case of spring planting, the most proper time for turf establishment was tested on April, May, and June trials. The effect was significant in establishment vigor. The result showed highest on April planting. On May and June trials, establishment vigors were decreased gradually As the mixture rate of PR increased, ryegrass, establishment vigor was decreased with the rates. These results indicated that perennial ryegrass has relatively less tolerant to summer heat than Kentucky bluegrass. Number of shoots in 95 days after seeding was higher in KB100 by 16,600 per $m^2$ than in PR100 by 12,400 per $m^2$, while the lowest number showed in KB50+PR50 by 3,300 per $m^2$. Those in KB80:PR20, KB70:PR30 were 6,700 and 4,900 per $m^2$, respectively. The ratios of tillers according to mixture rates between Kentucky bluegrass and perennial ryegrass were KB80:PR20=87:13, KB70:PR30=78:22, and KB50:PR50=48:52. According to results in this study, Ideal seeding time might be spring (April) than in fall (September), and proper mixture rate was $80\%$ of Kentucky bluegrass with $20\%$ of perennial ryegrass.

• Journal of Preventive Medicine and Public Health
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• v.30 no.2 s.57
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• pp.381-391
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• 1997

In an epidemiological study of metal workers exposed to metalworking fluids (MWF), the prevalence time of Evolution, seasonal occurrence and clinical type of contact dermatitis were investigated. Compostional analysis of MWF with HPLC, dermatological examination and two consecutive questionnaire surveys were conducted. Study population was divided into two groups ; workers contact to cutting oil and workers contact to rust preventive oil. In the analysis of MWF, aliphatic hydrocarbons, having 12-20 carbons, was most common composition(49.04%) of cutting oil otherwise, major contents (90.99%) of the rust preventives oil were aliphatic hydrocarbons composed of 6-9 carbons. The frequency (point prevalence) of contact dermatitis(CD) was 7(12.7 per 100 subjects) in the dermatological examination of 55 workers. As the result of second survey for contact dermatitis, cumulative prevalence of oil working full-time and recent 1 year prevalence in two groups were 28.0, 16.7 and 15.1, 12.5 per 100 subjects. There were no difference in the prevalence of CD by oil, age, oil contact duration. Summer is the most common evolution season in workers exposed to cutting oil, but not in workers exposed to rust preventive oil. Major clinical type of CD was erythematous papules in both groups. It presents the importance of preventive measures that 51.1% suffer from contact dermatitis had medical care at their own expense, and 47.1% of them felt serious about their contact dermatitis. From the fact that 68.6% think cotton gloves protective apparatus, we emphasize the need for health education.

• Korean Journal of Poultry Science
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• v.17 no.3
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• pp.179-191
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• 1990

In order to study the effects of supplementation of live yeast(Saccharomyces cerevisiae) on the performance of laying hens, five experiments were conducted. Two experiment were conducted during summer period, one with 37 wk old Dekalb-Delta strain laying birds(Exp. 1) and the other one with 100 wk old molted Nick Chick Brown laying birds(Esp.2) . In each experiment, 240 birds were divided into 12 groups of 20 birds each and randomly distributed. Each of the two experimental diets(Control 71 and 0.05% live yeast supplemented 72) was fed to 6 groups for 4 wks in Exp.1 and 3 wks in Exp.2. Three experiments were conducted during winter period, Exp.2 with 54 wk old Hy-Line strain laying birds, Exp.4 with 52 wk old Hy-Line strain laying birds, and Exp.5 with 36 wk old broiler breeder(Indian River strain). In each experiment, 540 birds were divided into 18 groups of 30 birds each and randomly distributed. Each of the 3 experimental diets(Control：$T_1$0.05% live yeast supplemented：$T_2$ and 0.1% live yeast supplemented ： T$_3$) was fed to 9 groups for 6 wks in Exp.3, 9 wks in Exp.4 and 4 wks in Exp.5. In Exp.4, Latin Square design was employed to determine the effects of switching feeds at 3 wk intervals. All hens were housed in cages of commercial farm and experimental diets were made with commercial layer feeds. In Experiment 1, egg production was significantly(P＜0.05) higher in $T_2$. Feed intake was significantly (P＜higher in 72 at 1st wk but 4 wk average was not significantly different. Feed efficiency was significantly(P＜0.01) better in 72 at End wk but 4 wk average was not significantly different. Other parameters, such as weight, soft egg production, cracked egg production and mortality were not significantly different. In Experiment 2, egg production was significantly(P＜0.05) higher in $T_2$. Feed efficiency was significantly (P＜0.05 and P＜0.01) better at End wk and 3rd wk but 3 wk average was not significantly different. Soft egg production was significantly(P＜0.05) higher in 72. Other parameters were not significantly different. In Experiment 3, egg productions were significantly(P＜0.05) different among treatments ： $T_3$ was higher than $T_1$ and $T_2$ was higher than $T_1$. Egg weight of $T_1$ and $T_2$was significantly(P＜0.05) heavier than $T_3$. Feed intake of $T_2$ and $T_3$ was significantly(P＜0.05) higher than $T_1$ at 6th wk but overall average was not significantly different. Soft egg production were significantly(P＜0.01) different among treatments：$T_1$ was higher than $T_3$ was higher than $T_2$. Feed efficiency cracked e99 Production and mortality were not signifcantly different. In Experiment 4, egg production tended to increase as the level of live yeast supplementation increased but they were not statistically different. In Experiment 5, egg production of broiler breeders of $T_3$ was significantly(P＜0.01) higher than $T_1$. Feed intake of $T_3$ was significantly(P＜0.05) greater than $T_1$ and $T_2$ at 3rd wk but overall average was not significantly different. Fertility and hatchability tended to be higher in the supplemented groups than in the control.

• Childhood Kidney Diseases
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• v.7 no.2
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• pp.166-173
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• 2003

Purpose : The cause and pathogenesis of $Henoch-Sch\"{o}nlein$ purpura has been studied for many years but the results are disappointing. Recently the hypothesis that abnormalities involving the glycosylation of the hinge region of immunoglobulin Al(IgAl) may have an important role in the pathogenesis of $Henoch-Sch\"{o}nlein$ purpura is being approved. $Henoch-Sch\"{o}nlein$ purpura is the most common vasculitis Ihat affects children and the prognosis is good. But if kidney invovement occurs, the course may be chronic and troublesome. So we evaluated children with $Henoch-Sch\"{o}nlein$ purpura especially from the point of epidemiology and clinical manifestations. Methods : Investigation of 124 children who were diagnosed with $Henoch-Sch\"{o}nlein$ purpura at Inje University Ilsan Paik Hospital from December 1999 to July 2003 was performed retrospectively through chart review. Efforts were made to get informations about the profile, epidemiology, clinical manifestations, progress of the disease and recurrence rate of patients. Results : The patients were 69 boys and 55 girls, with a mean age of $6.1{\pm}2.7$ years at the time of data collection. The male to female ratio was 1.25 : 1. The occurrence rate was much higher in autumn(from September to November, 31.5%) and winter(from December to February, 28.2%) than in spring and summer, with a peak in November. Joint involvement was shown in 66.9% of patients mostly on the foot/ankle(75.9%), knee(39.8%). Seventy(56.5%) out of 124 patients had abdominal pain and 10 patients(8.1%) showed bloody stools. Renal involvement was observed in 24 patients(19.4%) after 21.1 days on the average. IgA was elevated in 10 of 21 patients(47.6%). $C_3$ and $C_4$ levels were normal in 40 of 49 patients (81.7%) and 47 of 48 patients(97.9%), respectively Antistreptolysin-O(ASO) titer was elevated over 250 Todd units in 29 of 62 Patients(46.8%). Mycoplasma antibody titer was elevated in 21 of 49 patients(42.9%) equal or greater than 1:80. Radiologic studies were peformed in 23 patients. Seven patients(30.4%) showed bowel wall thickening and one of them received intestinal resection and anastomosis operation due to terminal ileum necrosis. Eighty four patients took steroid 1.4 mg/kg/day in average. Recurrence rate was 2.5 in 37 patients(29.8%). Conclusion : $Henoch-Sch\"{o}nlein$ purpura in childhood appears most in about 6 years of age. The occurrence rate is much higher in autumn and winter relatively. Diagnosis can be made through the perspective history taking and the inspection of clinical manifestations, but the laboratory findings are not of great help. A small portion of the patients might show abdominal pain or arthritis before purpura develops, therfore various diagnosis can be made. Radiologic evaluation should be performed to avoid surgical complications in cases accompanying abdominal pain, and long term follow up should be needed especially in patients suffering from kidney involvement. In about 30% of the patients $Henoch-Sch\"{o}nlein$ purpura would recur. Steroid can be used safely without side effects.

• Korean Journal of Organic Agriculture
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• v.7 no.1
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• pp.91-103
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• 1998

After the consumption of green vegetable juice by Korean increase rapidly, the ${NO_3}^-$ intake through green vegetable juice have been ignored to consider for the calculation of daily ${NO_3}^-$ intake. It is necessary to collect the basic data on the ${NO_3}^-$ content in green vegetable juice by different sorts, harvesting time and mixing rate of vegetable, manufacturers and storage conditions for the next calculation of daily ${NO_3}^-$ intake for Korean. Followings are the research results from monitoring and laboratory experiment related with ${NO_3}^-$ and vitamine C in green vegetable juice. The ${NO_3}^-$ content of angelica plaant(tomorrow's leaf) and kale were higher in spring than those in summer and autumm. The highest value of ${NO_3}^-$ content in tomorrow's leaf and kale were 4.85 and 2.94 times higher compare to the lowest value. The average ${NO_3}^-$ content in the midribs of tomorrow's leaf and kale were 7.5 and 2.1 times higher than those in leafblades. It indicate the green vegetable juice made from leadblade of tomorrow's leaf and kale might be better compare to those from midrib in terms of ${NO_3}^-$ content. The content of ${NO_3}^-$ and vitamine C as affected by the timecourse after juice making were decreased rapidly compare to those by storage temperature in case of carrot, kale and cucumber juice. It show the positive comelation between the content of ${NO_3}^-$ and vitamine C in carrot, kale and cucumber juice regardless of room temperature(${NO_3}^-$) or cold temperature(${NO_3}^-$). The content of ${NO_3}^-$ and vitamine C of green vegetable juice by P company were the highest among the manufactuers. The lower content of ${NO_3}^-$ and vitamine C of green vegecable juice by TW company and GB company compare to P company is due to dilution with water to produce the juice. The content of ${NO_3}^-$ of green vegetable juice which were available in market showed 143ppm in carrot juice, 506ppm in tomorrow's leaf juice, 669ppm in wild water celery juice, 985ppm in kale juice, whereas the content of vitamine C were 43ppm in carrot juice, 289ppm in wild water celery juice, 353ppm in kale juice and 768ppm in tomorrow's leaf juice. It was calculated that people take 253mg by tomorrow's leaf juice, 335mg by wild water celery juice, 483mg by kale juice if they drink 500ml of green vegetable juice perday, and it suggest to excess 1.16, 1.53 and 2.21 times respectively only by green vegetable juice consumption.

• Journal of Food Hygiene and Safety
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• v.32 no.2
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• pp.123-128
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• 2017

The purpose of this study was to determine the sodium (Na) and potassium (K) content of seasonal foods Four hundred food samples classified into 8 different kinds of seasonal foods were collected from 150 restaurants located in Seoul. The Na and K content in seasonal foods were the analyzed by ICP-OES. The Average content of Na and K in spicy seafood noodle soup were highest as $391.4{\pm}72.7mg$/100 g and $88.6{\pm}21.4mg$/100 g, respectly, while average content of Na was lowest in spicy buckwheat noodles as $255.3{\pm}67.0mg$/ 100 g and the average content of K was lowest in Udon as $36.3{\pm}17.8mg$/ 100 g, respectively. The Na/K ratio of spicy buckwheat noodles was $3.2{\pm}1.0$, while those of cold buckwheat noodles, fish cake, Udon were very high as measured more than 8. Among the seasonal foods, the average content of Na was highest in Winter group as $366.9{\pm}81.8mg$/ 100 g and the average content of K was highest in Autumn group as $84.8{\pm}24.1mg$/ 100 g. The ratio of Na/K was lowest in Summer group as $5.9{\pm}3.3$.