• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.212-219
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• 2004

To minimize the danger of soil erosion and settle habitats earlier, afforestation, which vegetates bare slopes, is selected as an environmental recovering technology. Large portions of these areas often are suffered by a bad germination and growth inhibition of sprayed seeds. Afforested materials collected in the normal and damaged sites were not any big difference in chemical characteristics and biological response to ryegrass. But background soil of the damaged site has very low pH (3.6) and high contents of iron and aluminum compared with them of the normal sites. Both germination and root growth of ryegrass were inhibited severely in the water extracts of damaged soils, but not in the water extracts of normal sites. Groundwater collected nearby the damaged sites was very strong acidic (pH 33) and exhibited a high value of electrical conductivity and high contents of iron and aluminum. In the ground water, germinated ryegrass was scarcely grown. In Al standard solution, the root growth of ryegrass was inhibited over 50% in 0.5 mM in pH 3.5-4.5 and in 1.4 mM in pH 5.5, which seems to be related to $Al^{3+}$ activity in solution. In the ferric Fe ($Fe^{3+}$) standard solution, ryegrass growth was inhibited over 50% in the concentration of 14-19 mM in root and 23-25 mM in shoot. This strong tolerance of ryegrass to $Fe^{3+}$ might be concerned with the very low activity of $Fe^{3+}$ at pH 3.5-5.5. In contrast, ryegrass responded very sensitively to ferrous Fe ion ($Fe^{2+}$), especially in root growth: $Fe^{2+}$ concentrations corresponding to 50% growth reduction were 0.3-0.4 mM at pH 3.5-5.5 in roots. This high growth inhibition should be related to the high ion activity of $Fe^{2+}$ irrespective of different pH conditions. In conclusion, low pH and high contents of $Fe^{2+}$ and aluminum seem to be caused by pyrite and be closely related to the growth inhibition of ryegrass seeded in afforested area.

• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.329-344
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• 2017

This study was carried out to investigate the hot pepper yield, chemical properties of soil and distribution of animalcule with split irrigation and input of organic matter under no-tillage hot pepper green house condition. After experiment, soil pH maintained range of 5.6~6.2 in whole treatments. Organic matter content of soil was range of $32{\sim}42g{\cdot}kg^{-1}$. Soil salinity (EC) content of soil was range of $1.0{\sim}2.7dS{\cdot}m^{-1}$. Exchangeable cations in soil were range of $0.08{\sim}0.24cmol^+{\cdot}kg^{-1}$ in K, $9.5{\sim}12.8cmol^+{\cdot}kg^{-1}$ in Ca, and $2.7{\sim}3.2cmol^+{\cdot}kg^{-1}$ in Mg. Avaliable phosphorus ($P_2O_4$) content in soil was range of $1,011{\sim}1,137mg{\cdot}kg^{-1}$. Yield of pepper was more decreased in treatment of soybean cake fertilizer than no-treatment of soybean cake fertilizer. Yield of pepper in treatment of soybean cake fertilizer was increased at 33% of standard fertilizer application. Yield of pepper in no-treatment of soybean cake fertilizer was increased at 33% and 66% of standard fertilizer application. Number of fruits was increased range of 12.5~34.9% at half division irrigation compared with whole quantity irrigation. Yield of pepper was increased range of 13.5~34.4% at half division irrigation compared with whole quantity irrigation. Nine index of nature status and 271 Individual were captured in treatment of soybean cake fertilizer. Five index of nature status and 54 Individual were captured in treatment of soybean cake fertilizer. Nature status for environmental change as index organism was 11 points and 5 points, at treatment of soybean cake fertilizer and no-treatment of soybean cake fertilizer, respectively.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.4
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• pp.31-39
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• 2017

From July to August 2013, liquid fertilizers produced at 180 liquid manure public resource centers and liquid fertilizer distribution centers were collected. The maturity of liquid fertilizers was measured using the mechanical maturity measurement device. The nutrient contents (nitrogen, phosphorus, and potassium), physicochemical properties, and heavy metal content of 46 liquid fertilizers were investigated in this study. We used a matured liquid fertilizer with a total number of 46, with number of 7 for Gyeonggi-do, 3 for Chungcheongbuk-do, 2 for Chungcheongnam-do, 13 for Jeollabuk-do, 5 for Jeollanam-do, 3 for Gyeongsangbuk-do, 11 for Gyeongsangnam-do, 1 for Daejeon, and 1 for Jeju-do. The physicochemical properties were as follows: pH 8.0, EC 11.6 mS/cm, SS 5,188 mg/L, TKN 847mg/L, ${{NH_4}^+}-N$ 317 mg/L, ${{NO_3}^-}-N$ 170 mg/L, Org-N 360 mg/L, TP 193 mg/L, and TK 2,557 mg/L. The total amount of NPK was 3,596 mg/L. The total amount of N-P-K was as follows: a number of 2 at 1,000-2,000 mg/L (4%), a number of 17 at 2,000-3,000mg/L (37%), a number of 11 at 3,000-4,000mg/L (24%), and a number of 16 at 4,000mg/L or more (35%). Thus, 41% of the mature liquid fertilizers were below the official standard of commercial fertilizer (livestock manure liquid fertilizer) (0.3% of the total amount of N-P-K). Most of the N-P-K total amount showed non-uniform characteristics of low nitrogen and low phosphoric acid due to the potassium concentration. The average heavy metal content in the matured liquid fertilizer was as follows: As, not detected; Cd, 0.01 mg/kg; Hg, not detected; Pb, 0.02 mg/kg; Cr, 0.14 mg/kg; Cu, 6.89 mg/kg; Ni, 0.44 mg/kg; and Zn, 20.70 mg/kg. Thus, the official standard of commercial fertilizer was satisfied in all categories, indicating a safe level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.510-523
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• 2020

This study analyzed groundwater quality in hydroponic cultivation facilities. Through this study, the possibility of groundwater use was evaluated according to the quality of the groundwater for hydroponic cultivation facilities. Good groundwater quality, on average, is pH 6.61, EC 0.27 dS/m, NO3-N 7.64 mg/L, NH4+-N 0.80 mg/L, PO4-P 0.09 mg/L, K+ 6.26 mg/L, Ca2+ 18.57 mg/L, Mg2+ 4.38 mg/L, Na+ 20.85 mg/L, etc. All of these satisfy the water quality standard for raw water in nutrient cultivation. But in the case of farmers experiencing problems with groundwater quality, most of the items exceeded the water quality standard. As a result of the analysis, it was judged that purifying groundwater of unsuitable quality for crop cultivation, and using it as raw water, was effective in terms of water quality and soil purification. If an agricultural water purification system is constructed based on the results of this study, it is judged that the design will be easy because the items to be treated can be estimated. If a purification system is established, it can use groundwater directly in the facility and for horticulture. These study results will be available for use in sustainable agriculture and environments.

• Current Research on Agriculture and Life Sciences
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• v.1
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• pp.85-93
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• 1983

Total annual water requirements for agricultural use are exceedingly large. In many areas of the country, particularly in the arid regions, irrigation water requirements comprise the bulk of the total developed water supply. On the other hand, we are, at present, poorly prepared to evaluate the hazards of many substances in the water phase of the agricultural environments. This study is to survey the water quality phase of agricultural conditions and to give some ideas to prevent disasters from the environmental hazards such as PH, Electric Conductivity, BOD, DO, Cu, Pb, and Cd. In the analysed results, mean PH was 6.5 to 7.8, maximum EC was $200{\mu}{\Omega}/cm$ at $25^{\circ}C$, the maximum BOD was less than 10 ppm (standard value), the DO was 4.2 to 12.0 mg/L (standard value is more than 2.0 mg/L) and the Cu, Pb, Cd were estimated in scope of safety value respectively. Especially BOD is gradually closed with the hazardous point in the few places. At present, the hazardous environmental conditions originated from the municipal sewage, industrial waste, and human and domestic animals excrements etc. have to strongly be improved much better than before.

• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.271-281
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• 2001

The Purpose of this study was fourfold - to evaluate the general laws of friction applied to orthodontic conditions, to compare archwire materials under these controlled conditions, to compare ligation method, and to measure the effect of the artificial saliva on friction with these materials Three wire alloys (Cobalt-chromium, Nickel-titanium, Beta-titanium) in two size wires (.016" , .016" ${\times}$.022" ) were examined respect to the bracket (.018" ${\times}$.025" standard), and two ligature material (stainless steel, elastomeric) in dry and wet conditions The results were as follows, 1. The order of frictional force against alloy materials was Co-Cr (lowest), Ni-Ti, and ${\beta}$-Ti(highest) - with the exception of elastomeric ligation under wet conditions. 2. S.S. ligation gave rise to significantly greater friction than elastomeric ligation did. 3. Testing in the presence of saliva, rather than in dry conditions, decreased the frictional force for S.S. ligation with .016" Co-Cr, Ni-Ti, ${\beta}$-Ti. but, increased the frictional force for S.S. ligation with .016" ${\times}$ .022" Co-Cr, Ni-Ti, ${\beta}$-Ti. 4. .016" ${\times}$.022 " wire generated more friction than .016" wire.

• The Journal of Advanced Prosthodontics
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• v.7 no.1
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• pp.56-61
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• 2015

PURPOSE. The purpose of this study was to evaluate the effects of the surface treatment and shape of the dental alloy on the composition of the prosthetic work and its metallic ion release in a corrosive medium after casting. MATERIALS AND METHODS. Orion Argos (Pd-Ag) and Orion Vesta (Pd-Cu) were used to cast two crowns and two disks. One of each was polished while the other was not. Two as-received alloys were also studied making a total of 5 specimens per alloy type. The specimens were submersed for 7 days in a lactic acid/sodium chloride solution (ISO standard 10271) and evaluated for surface structure characterization using SEM/EDAX. The solutions were quantitatively analysed for the presence of metal ions using ICP-MS and the results were statistically analysed with one-way ANOVA and a Tukey post-hoc test. RESULTS. Palladium is released from all specimens studied (range $0.06-7.08{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$), with the Pd-Cu alloy releasing the highest amounts. For both types of alloys, ion release of both disk and crown pairs were statistically different from the as-received alloy except for the Pd-Ag polished crown (P>.05). For both alloy type, disk-shaped pairs and unpolished specimens released the highest amounts of Pd ions (range $0.34-7.08{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$). Interestingly, in solutions submerged with cast alloys trace amounts of unexpected elements were measured. CONCLUSION. Shape and surface treatment influence ion release from dental alloys; polishing is a determinant factor. The release rate of cast and polished Pd alloys is between $0.06-0.69{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$, which is close to or exceeding the EU Nickel Directive 94/27/EC compensated for the molecular mass of Pd ($0.4{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$). The composition of the alloy does not represent the element release, therefore we recommend manufacturers to report element release after ISO standard corrosion tests beside the original composition.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.3
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• pp.232-238
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• 2005

There are growing needs for improving the general performances of the domestic working environment evaluation organizations. For this purpose, introduction of laboratory accreditation program has been suggested. This study was conducted as a part of this effort. With a questionnaire developed in accordance with the ISO/IEC 17025, the current status of industrial hygiene (IH) laboratories in terms of manpower, management and technical aspects. The results of this study were as follows: 1. The average working staffs' number of the working environment evaluation organizations was $6.8{\pm}3.3$ persons. In addition, 49% of all organizations are run by less than 5 persons. This suggests that manpower of Korean IH laboratories is very limited. 2. IH laboratories surveyed in this study obtained 53% of the points by the international standard. And there is significant correlation between the number of staffing and total scores (P<0.05). 3. The period of work experience is one of the most important factors to determine the working capability. The average year of work experience of the laboratories' directors was $13.5{\pm}5.3$ years. Directors with more wok experiences obtained higher scores on the questions that ask to prove the appropriateness of the research methodology (p<0.05). 4. As for academic qualifications of laboratory directors, 14% had Ph.D., 31% with Master's, 29% with Bachelor's, and 4% had Associate degree. There was significant correlation between the total scores and the general managers' academic background (p<0.05). The 27% of laboratory directors have majored in either industrial hygiene or health, 8% majored in medicine, another 8% majored environmental studies, and 6% majored in chemistry. 5. Only 14% of all IH laboratories surveyed employ directors with Certified Industrial Hygienist licence, 41% have general managers with Certified Associate Industrial Hygienist (Level 1) licence, and 45% of all laboratories either employ directors without relevant qualification or did not respond. When the laboratory manger holds relevant qualification, laboratory health and safety management was better (p<0.05). 6. When compared to the general international standard in terms of the management, and 55% in terms of technological level.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.117-127
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• 2008

Green algae are important primary producers in aquatic ecosystem, and they are sensitive test species in bioassay. Green algae are broadly used to assess the adverse effects of various chemicals by measuring the inhibition of metabolism, reproduction and survival. In this study, we extensively gathered domestic and foreign toxicity test methods conducted using green algae, which are distributed in Korean water environment. Selected eight domestic green algae were Chlamydomonas reinhardtii, Desmodesmus subspicatus (=Scenedesmus subspicatus), Scenedesmus abundans, Scenedesmus acutus, Scenedesmus quadricauda, Podohedriella falcata (=Ankistrodesmus falcatus), Pseudokirchneriella subcapitata (=Selenastrum capricornutum), and Chlorella vulgaris. Forty four test methods were collected from the standard test ones, government reports, SCI papers and Korean research papers. P. subcapitata and D. subspicatus are the most common test species recommended by the standard test methods. Initial cell density and dilution water were the main differences among the test methods we collected. We proposed the suitable ecotoxicity test methods based on domestic green algae in Korea. This study could be a fundamental basis to establish the ecotoxicity test methods by green algae distributed in Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.1
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• pp.40-46
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• 2000

The investigation and the analysis of soil chemical properties, microbial flora and cultural practices in plastic house of 60 farms (pepper 20, cucumber 20, oriental melon 20) were conducted in Chonnam area film. An amount of fertilizer application of farms was more than that of standard fertilizer application. That was phosphate at two and a half times, potassium at twice and manure at three times the amount of standard application. It was inferred that excessive fertilizer application would lead to salts accumulation in soil. Continuous cropping injury would be incurred by excesive salts accumulation in soil. Even if inorganic elements in soil culturing peppers, cucumbers and oriental melons were greater than optimum level, base-saturation degree of soil culturing peppers, cucumbers and oriental melons was 40:18:12, 55:16:14 and 40:27:11 respectively. That was lower than the optimum levels (60:15:5). Therefore, crops would be affected by uptake inhibition by nutrition imbalance. Density of Fusarium is related to plant decease in soil i.e. pepper $26.2{\times}10^2\;cfu\;g^{-1}$, cucumber $75.8{\times}10^2\;cfu\;g^{-1}$ and oriental melon $6.5{\times}10^2\;cfu\;g^{-1}$. B/F of soil planted with pepper, cucumber and oriental melon was 91.2, 80.4 and 18.8, respectively.