• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.1-10
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• 2008

The seasonal variations of water quality and periphyton were investigated in an artificial stream (the Cheonggyecheon Stream) flowing through the Seoul City. TP showed a longitudinal gradient: 10 to $59{\mu}gP\;L^{-1}$ in the upper stream sites, and 15 to $90{\mu}gP\;L^{-1}$ in downstream sites. POP was a major form of TP in the water, occupying over 60%, while the proportion of DIP was less than 10% except for St. 4. N/P atomic ratio ranged from 78 to 554, which implies phosphorus would limit algal growth more than nitrogen. The biomass of periphyton did not show much difference among sites, and it was relatively higher in spring and fall season $(10\sim20{\mu}gChl\;{\alpha}cm^{-2})$ and lower in August $(<5{\mu}gChl\;{\alpha}cm^{-2})$, possibly because biofilms were washed off during spates of summer monsoon. Cyanobacteria was the dominant taxon in the periphyton community throughout the year. The periphyton standing crop can be classified as a nuisance level. It seems that phosphorus level is sufficiently high even though the input water is treated chemically, and modest water velocity $(20\sim90cm\;sec^{-1})$ and rocky bottom provide optimal conditions for periphyton growth.

• Korean Journal of Food Science and Technology
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• v.46 no.3
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• pp.269-275
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• 2014

We developed a competitive indirect enzyme-linked immunosorbent assay (ciELISA) for determining the buckwheat content in processed foods by using rabbit polyclonal antibodies against buckwheat proteins (BWP). The detection limit of this assay was $0.05-100{\mu}g/mL$. The cross-reactivities of the anti-BWP antibodies toward BWP, buckwheat flour, whole buckwheat, and cereals (wheat flour, whole wheat, black bean, mung bean, red bean, brack rice, brown rice, glutinous rice, white rice, millet, African millet, nonglutinous millet, adlay, and rye) were 100, 17.9, 11.8, and 0%, respectively. Thus, the antibodies were found to be specific for buckwheat only. When buckwheat flour was heated for 30 min, the mean assay recoveries of BWP were 83.0% at $60-90^{\circ}C$ and 44.5% at $100^{\circ}C$. The spike test showed that the mean assay recoveries of buckwheat from raw noodle, boiled noodle, starch gel, and cereal flour were 99.1, 98.6, 81.1, and 104%, respectively. For the 22 commercial items tested, the qualitative coincidence ratio of assay result and the corresponding value indicated on the item's package label was 100%. However, the average quantitative coincidence ratios from 12 commercial items were 31.6%. Thus, the results suggest that ciELISA is an efficient tool to detect buckwheat in processed foods.

• Food Science of Animal Resources
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• v.32 no.4
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• pp.483-490
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• 2012

Ready-to-eat chicken breasts were packaged in a multilayer, gas-tight tray with top film and various quality changes were investigated during the 24 wk of storage at $10^{\circ}C$. Over the storage period, total aerobes, mesophilic aerobic and anaerobic spore formers, and Clostridium spp. were not detected above 1.0 log CFU/g (detection limit). The residual oxygen ratio in the head space of tray and pH values tended to decrease with storage time, namely from initial values of 5.7% and 6.56 to 3.3% and 6.34 at week 24, respectively. Thiobarbituric acid reactive substances and volatile basic nitrogen values increased from 0.52 mg malonaldehyde (MA)/kg and 2.1 mg/100 g initially, to 3.70 mg MA/kg and 39.9 mg/100 g at week 24, respectively. In terms of the change in meat color during storage, the samples showed a slight increasing trend of CIE $a^*$, $b^*$, and ${\Delta}E$ values over the storage period until week 24 (p<0.05). The change in brine color showed a similar trend with meat of which Hunter $b^*$ and ${\Delta}E$ values increased slightly during storage during 24 wk (p<0.05). The values for the transmittance degree of brine in the samples tended to decrease. Moreover, values for the absorbance degree tended to increase with storage time until week 24. The sensory scores for color, texture, odour, and flavour were evaluated below 5.0 (marketability level) after 24 wk of storage. Based on this sensory evaluation, it could be concluded that retorted RTE chicken breast could remain marketable for at least 20 wk at $10^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.969-976
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• 2002

The migrating level of di-(2-ethylhexyl) adipate (DEHA) in PVC wrap to various foodstuffs dishes was determined using acetone/n-hexane as an extracting solvent. The recovery ratio of DEHA from various foodstuffs ranged from 81.3 to 91.2%. During storage at $10\;or\;20^{\circ}C$ for up to 3 days, highest migration of 22.9 mg/kg occurred with pork belly, an indication that increases in fat content, storage temperature, and storage time result in increasing DEHA migration. DEHA concentrations of various delivered dishes ranged between 6.9 and 29.8 mg/kg, and highest migration was observed in Chambbong, which had the highest fat content among samples. After microwave-reheating, which resulted in a tight contact between film and food samples, DEHA was not detected in rice and potato, whereas up to 158.8 mg/kg was detected in pizza. When the wrap film was not contacted with the surface of food, the migration was lowered. Migration levels of DEHA from PVC wrap film into samples under various exposure conditions often exceeded the limit value of $3\;mg/dm^2\;and/or\;18\;mg/kg$ set by the European Union.

• Journal of Distribution Science
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• v.14 no.4
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• pp.39-46
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• 2016

Purpose - Recently, as Korean culture and economy develops, Seoul has become a world-famed city. In Seoul, many special grade hotels have been constructed in order to accommodate many tourists from China, Japan and many other Asian countries. And the hotels entered into competition among themselves. Thus many changes are accelerated due to their mutual competition and manpower problems. In this situation, the role of higher officers above all is thought to be very important in order to enhance the management result and to make preparations for the kernel ability of the organization. Research design, data and methodology - This study was intended to verify how the leadership of the higher officers based on trust affects the job satisfaction of employees of the organization. In order to achieve the purpose of this study, some study models and hypotheses have been established through theoretical examinations. The subjects of this study were centered on the constituents of C-Hotel, M-Hotel, and D-Hotel. 200 questionaries were distributed and 190 questionaries were collected and thus the collection ratio was 91 percent. 8 questionaries which were regarded to be insincere or hard to analyzed were excluded. Finally, 182 questionaries were used for analyzing the factors and trust. For the purpose of the verification of hypotheses, structural equation was used. In order to verify the mediating effect of trust between the relationship of emotional leadership and job satisfaction, 'Three-step Mediated Regression Analysis by Baron & Kenny(1986) was utilized. The four hypotheses for this study are as follows: First, emotional leadership will have a meaningful influence on trust in the affirmative. Second, trust will have a meaningful influence on job satisfaction in the affirmative. Third, trust will play a mediating role in the relationship of emotional leadership and job satisfaction. Result - First, the emotional leadership and trust was found to effect a positive effect. Second, the trust and job satisfaction was found on a positive effect on job satisfaction. Third, the emotional leadership and job satisfaction was found to positive effect on job satisfaction. Fourth, the trust in the relationship between emotional leadership and job satisfaction was found that the partial mediating effect. Especially, in the case of the business of hospitality, human services as well as material resources become its keynote, and we can safely say that the degree of dependence toward human resources is very high. Accordingly, the leaders should display their leadership on the basis of abundant emotional and intellectual faculties so that they can grasp, understand and admit the diverse views of value and emotion of the organization constituents and that they can form emotional leadership. On the basis of the analysis results of the verification of hypotheses, some suggestions and uppermost limit of this study have been presented for further study.

• Bulletin of the Korean Chemical Society
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• v.22 no.1
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• pp.30-36
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• 2001

The crystal structures of fully dehydrated $Pd^{2+}$ - and $TI^{+}$ -exchanged zeolite X, $Pd_{18}TI_{56}Si_{100}Al_{92}O_{384}(Pd_{18}TI_{50-}X$, a = $24.935(4)\AA$ and $Pd_{21}TI_{50}Si_{100}Al_{92}O_{384}(Pd_{21}TI_{50-}X$ a = $24.914(4)\AA)$, have been determined by single-crystal X-ray diffraction methods in the cubic space group Fd3 at $21(1)^{\circ}C.$ The crystals were prepared using an exchange solution that had a $Pd(NH_3)_4Cl_2\;:TINO_3$ mole ratio of 50 : 1 and 200 : 1, respectively, with a total concentration of 0.05M for 4 days. After dehydration at $360^{\circ}C$ and 2 ${\times}$$10^{-6}$ Torr in flowing oxygen for 2 days, the crystals were evacuated at $21(1)^{\circ}C$ for 2 hours. They were refined to the final error indices $R_1$ = 0.045 and $R_2$ = 0.038 with 344 reflections for $Pd_{18}Tl_{56-}X$, and $R_1$ = 0.043 and $R_2$ = 0.045 with 280 reflections for $Pd_{21}Tl_{50-}X$; I > $3\sigma(I).$ In the structure of dehydrated $Pd_{18}Tl_{56-}X$, eighteen $Pd^{2+}$ ions and fourteen $TI^{+}$ ions are located at site I'. About twenty-seven $TI^{+}$ ions occupy site II recessed $1.74\AA$ into a supercage from the plane of three oxygens. The remaining fifteen $TI^{+}$ ions are distributed over two non-equivalent III' sites, with occupancies of 11 and 4, respectively. In the structure of $Pd_{21}Tl_{50-}X$, twenty $Pd^{2+}$ and ten $TI^{+}$ ions occupy site I', and one $Pd^{2+}$ ion is at site I. About twenty-three $TI^{+}$ ions occupy site II, and the remaining seventeen $TI^{+}$ ions are distributed over two different III' sites. $Pd^{2+}$ ions show a limit of exchange (ca. 39% and 46%), though their concentration of exchange was much higher than that of $TI^{+}$ ions. $Pd^{2+}$ ions tend to occupy site I', where they fit the double six-ring plane as nearly ideal trigonal planar. $TI^{+}$ ions fill the remaining I' sites, then occupy site II and two different III' sites. The two crystal structures show that approximately two and one-half I' sites per sodalite cage may be occupied by $Pd^{2+}$ ions. The remaining I' sites are occupied by $TI^{+}$ ions with Tl-O bond distance that is shorter than the sum of their ionic radii. The electrostatic repulsion between two large $TI^{+}$ ions and between $TI^{+}$ and $Pd^{2+}$ ions in the same $\beta-cage$ pushes each other to the charged six-ring planes. It causes the Tl-O bond to have some covalent character. However, $TI^{+}$ ions at site II form ionic bonds with three oxygens because the super-cage has the available space to obtain the reliable ionic bonds.

• Journal of agriculture & life science
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• v.45 no.5
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• pp.73-80
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• 2011

Fifty substances of pesticide were selected for analysis through the historical investigation of pesticides detected from environmental-friendly agricultural soil, and the environmental-friendly agricultural soils in Gyeongnam area were collected and then were accepted Anve (accelerated solvent extraction) and SPve (solid-phase extraction) as multiresidue extraction and clean up methods suitable to the soils. The pesticide residues were analyzed by using GC/vCD/NPD, HPLC/UV/FL, GC/MSD, or HPLC/MSD. 50 kinds of pesticides for the soils were an average of 95.5% from retrieval ratio of the 72 to 118% range, and the average of 3.0% for CV (%). Among 40 samples of soil, 20 components were detected from pesticide residues of 21 samples, and average amounts detected for these components were 0.035 for endosulfan, 0.043 for ethoprophos, 0.020 for chlorpyrifos, 0.023 for chlorfenapyr, 0.047 for flufenoxuron, 0.070 for fenvalerate, 0.266 for cypermethrin, 0.016 for lufenuron, 0.022 for bifenthrin, 0.025 for fenobucarb/BPMC, 0.043 for difenoconazole, 0.059 for fenarimol, 0.020 for kresoxim-methyl, 0.026 for tetraconazole, 0.039 for isoprothiolane, 0.017 for iprobenfos, 0.014 for nolrimol, 0.156 for fluquinconazole, 0.047 for tebuconazole, and 0.045 mg/kg for oxadiazon. Therefore it is infered that the establishment of pesticide residues limit for environmental-friendly agricultural soil is needed as soon as possible.

• Tunnel and Underground Space
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• v.29 no.5
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• pp.346-355
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• 2019

When evaluating pillar stability in very closely spaced tunnels, a local safety factor (strength/stress ratio) at the minimum width has been widely used. Tension bolts have been frequently applied as reinforcement for the cases where safety factors are less than 1.0 from FEM stress analysis. However, the local safety factor shows a constant value irrespective of the change in pillar width/tunnel diameter (PW/D) and the safety factor of the pillar is underestimated because the variation of deviation stress is relatively small even when the pre-stressing is applied to the tension bolt. In addition, the average safety factor proposed by Hoek and Brown(1980) was reviewed, but the pillar safety factor was relatively overestimated when the width of the pillar was increased. As an alternative, the SRM safety factor using shear strength reduction method shows the effect of changing the safety factor in the case of no reinforcement and tension bolt reinforcement as the pillar width/tunnel diameter(PW/D) changes. The failure shape is also similar to the previous limit theory result. In this study, the safety factor was evaluated without considering rock bolt and shotcrete to distinguish reinforcing effect of tension bolt.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.3
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• pp.279-286
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• 2019

In this study, an experimental study on the tensile properties of steel fiber-reinforced ultra high strength concrete(UHSC) with a standard compressive strength of 180MPa was performed. Steel fibers with a volume ratio of 1% were mixed to prepare direct tensile strength specimens and prism specimens for the three-point bending test. The fabricated specimens were set up in the middle section of the specimen to induce cracks, and the test was carried out according to each evaluation method. First, the stress-strain curves were analyzed by performing direct tensile strength tests to investigate the behavior characteristics of concrete after cracking. In addition, the load-CMOD curve was obtained through the three-point bending test, and the inverse analysis was performed to evaluate the stress-strain curve. Tensile behavior characteristics of the direct tensile test and the three-point bending test of the indirect test were similar. In addition, the tensile stress-strain curve modeling presented in the SC structural design guidelines was performed, and the comparative analysis of the measured and predicted values was performed. When the material reduction factor of 1.0 was applied, the predicted value was similar to the measured value up to the strain of 0.02, but when the material reduction factor of 0.8 was applied, the predicted value was close to the lower limit of the measured value. In addition, when the strain was greater than 0.02, the predicted value by SC structural design guideline to underestimated the measured value.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.2 s.25
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• pp.107-113
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• 2006

Water treatment plant sludge occurred in sedimentation and inverse wash process is generally disposed by ocean dumping or reclamation after dehydration processing using mechanical or natural dry method. Recently, ocean dumping of sludge is limited actually by London Convention. Physical, chemical, and geotechnical characteristics of water treatment plant sludge were analyzed by experiments. The possibilities for recycling of the dehydration sludges as materials for covering sanitary landfill were examined. Experiments performed with sludges mixed with general soil to improved the sludge properties are the hydrometer analysis, the liquid and plastic limit test, the specific gravity test, the compaction test, and the unconfined compression test. The value of ${\gamma}_{dmax}$ is increased and OMC(Optimum Moisture Content) is lessened with mixed sludge. The value of maximum compressive strength and friction angle are increased and the cohesion is decreased with mixed sludge. The ratio between sludge and soil in mixed sludge was 3:7 and the strength of mixed sludge showed $3.6kg/cm^2$. These results satisfy the regulation of U.S. E.P.A regarding materials for covering sanitary landfill.