• Journal of Korea Foundry Society
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• v.44 no.4
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• pp.97-102
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• 2024

In this study, the properties of Zr-14Cu-7.5Ni-2.6Al wide ribbon with amorphous structure and properties were analyzed using Hall effect, SEM-EDX, and XRD. Made by melt spinning method, this Zr-14Cu-7.5Ni-2.6Al based alloy ribbon is not more than 96 ㎛ thick and 100 mm wide. This amorphous alloy exhibited tensile strength of 1,641 MPa, yield strength of 1,541 MPa, elongation of 1% and elastic modulus of 98GPa. The bulk concentration, resistivity, and mobility values are midway between general heavy doping ceramics and metals, and they are about 100 times weaker than ordinary metals, so they are close to Si and have good electrical conductivity. In addition, folding tests were conducted at extreme temperatures, withstanding 150,000 times at -20℃, 300,000 times at 24℃, and 150,000 times at 60℃, with no folding defects observed. These results demonstrate the excellent durability and reliability of the Zr-14Cu-7.5Ni-2.6Al wide ribbon alloy and suggest the possibility of developing electronic products using this alloy.

• Analytical Science and Technology
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• v.31 no.1
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• pp.39-46
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• 2018

Carbaryl and seven organophosphorous pesticides were analyzed simultaneously using on-line solid phase extraction (on-line SPE) coupled with liquid chromatography tandem mass spectrometry (LC/MS/MS). The target pesticides are Carbaryl, Methyl demeton, Fenitrothion, Malathion, Parathion, Phenthoate, Diazinon, and EPN. This method includes the direct injection of $500{\mu}L$ in the water sample, a 15 min separation period using a rapid resolution liquid chromatography system with on-line SPE, and detection through electrospray ionization (ESI) positive mode. The percentage of recovery of all pesticides ranged from 85.3 % to 100 %. This method showed an accuracy of ${\geq}90.0%$, possessing limits of detection and quantification within 0.05 to $0.28{\mu}g/L$ and 0.16 to $0.89{\mu}g/L$, respectively. The correlation coefficients (r) for the calibration curves within a range of 0.5 to $8.0{\mu}g/L$ were higher than 0.99. The evaluation results showed the efficacy of the method for all contents, and no pesticides were detected in the water quality sample.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.3
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• pp.255-263
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• 2011

Projected increases in atmospheric $CO_2$ concentration ([$CO_2$]) and temperature ($T_a$) have the potential to alter in rice growth and yield. However, little is known about whether $T_a$ warming with elevated [$CO_2$] modify plant architecture. To better understand the vertical profiles of leaf area index (LAI) and the flag leaf morphology of rice grown under elevated $T_a$ and [$CO_2$], we conducted a temperature gradient field chamber (TGC) experiment at Gwangju, Korea. Rice (Oryza sativa L. cv. Dongjin1ho) was grown at two [$CO_2$] [386 (ambient) vs 592 ppmV (elevated)] and three $T_a$ regimes [26.8 ($\approx$ambient), 28.1 and $29.8^{\circ}C$] in six independent field TGCs. While elevated $T_a$ did not alter total LAI, elevated [$CO_2$] tended to reduce (c. 6.6%) the LAI. At a given canopy layer, the LAI was affected neither by elevated [$CO_2$] nor by elevated $T_a$, allocating the largest LAI in the middle part of the canopy. However, the fraction of LAI distributed in a higher and in a lower layer was strongly affected by elevated $T_a$; on average, the LAI distributed in the 75-90 cm (and 45-60 cm) layer of total LAI was 9.4% (and 35.0%), 18.8% (25.9%) and 18.6% (29.2%) in ambient $T_a$, $1.3^{\circ}C$ and $3.0^{\circ}C$ above ambient $T_a$, respectively. Most of the parameters related to flag leaf morphology was negated with elevated [$CO_2$]; there were about 12%, 5%, 7.5%, 15% and 21% decreases in length (L), width (W), L:W ratio, area and mass of the flag leaf, respectively, at elevated [$CO_2$]. However, the negative effect of elevated [$CO_2$] was offset to some extent by $T_a$ warming. All modifications observed were directly or indirectly associated with either stimulated leaf expansion or crop phenology under $T_a$ warming with elevated [$CO_2$]. We conclude that plant architecture and flag leaf morphology of rice can be modified both by $T_a$ warming and elevated [$CO_2$] via altering crop phenology and the extent of leaf expansion.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.562-568
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• 1998

Rice (Dongjin-byeo) added with black rices (Chindo and Suwon-415) was cooked and the changes of texture and color of this cooked rice were investigated by texture analyser and color & color difference meter. The hydration time to come to the equilibrium condition was at least 11 hr in black rices. The optimum ratio of water to cooked rice added with black rice was 1.6 (ratio of water to rice) and the hardness of cooked rice added with 5% Chindo black rice was $5.66\;kg_f$. Regardless of ratio of water to rice, Hunter a value increased as the ratio of black rice addition to rice increased, while L value decreased. The color elution rate of Suwon 415 was 4 times greater than that of Chindo black rice. The pH of the steep water of Suwon 415 at $20^{\circ}C$ during 120 min decreased from pH 6.40 to pH 6.16 as the steeping time increased. The optimum heating time by microwave oven of cooked rice added with black rice was between $90{\sim}120\;sec$ to recover the original texture after cold storage treatment of 7 days.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.312-312
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• 2023

동진강 유역은 김제평야를 품고 있어 다른 지역에 비해 농지면적이 차지하는 비중이 크며, 이에 따라 전체 용수 사용량에서 농업용수의 비중이 절대적으로 높은 유역이다. 낙양 보는 동진강 중·상류에 위치한 이수시설로 상류에 위치한 섬진강댐과 같이 동진강 유역의 농업용수 공급에 중요한 역할을 하고 있다. 낙양 보는 현재 동진강 방수문 4문, 김제간선 취입수문 2문, 정읍간선 취입수문 1문이 설치되어 있다. 관개기에는 동진강 도수로의 수문을 폐쇄하여 동진강 본류로의 하천유지용수를 차단하고 김제 배수로의 수문을 운용하여 농업용수를 공급하고 있으며 수혜구역의 용수수요 변화 및 기상상황, 하천상황에 따라 탄력적으로 운영하고 있다. 이러한 가동 보 운영으로 인하여 다양한 수위-유량관계의 변동성이 발생한다. 본 연구에서는 가동 보 운영에 따른 수위-유량관계 곡선식의 변동성을 확인하기 위해 동진강 유역 낙양보 상류에 위치한 정읍시(거산교)관측소를 대상관측소로 선정하였다. 정읍시(거산교)관측소는 2012년에 개발된 수위-유량관계곡선을 2021년까지 사용하였고, 2022년 수위-유량관계곡선식 검증과 재개발을 위하여 유량측정을 실시하였다. 2012년에 개발된 수위-유량관계곡선은 검토 결과 강우에 의한 수위 상승시 보 완전 개방 상태의 측정성과를 확보하여 수위-유량관계 곡선식을 개발하였다. 그 결과 가동 보를 운영하는 3월~9월은 상류에 위치한 정읍시(행정교)관측소와 상하류 역전 현상이 발생하였고, 매년 비정상적인 유량이 산정되는 결과를 초래하였다. 2022년 신뢰도 높은 유량자료와 수위-유량관계곡선식 개발을 위해 낙양 보 완전개방 및 부분개방에 따른 다양한 유량측정성과와 낙양 보 수문 모니터링 결과를 확보하였다. 낙양 보는 2022년 1월~3월, 10월~12월은 수문 6문을 완전 개방하여 동진강에 하천유지용수를 공급하고, 4월부터 동진강 방수문을 폐쇄하여 농번기 농업용수를 확보한 후, 5월~9월에 확보된 농용수를 김제 배수문 2문을 부분개방하면서 공급하는 방식이다. 이 기간동안 낙양 보 수문에 대한 모니터링을 위해 정읍시(거산교)관측소 수위자료에 대한 검토를 실시하였으며, 유량측정시에는 정확한 유량측정성과와 곡선식 확인을 위하여 동일한 위치에서 측정을 수행하였다. 또한, 수위 또는 유량이 변하는 구간은 연속측정을 실시하였으며, 모니터링 결과와 유량측정성과를 바탕으로 수위-유량관계 변화를 분석하였다. 그 결과 저수위1식은 수문 완전개방, 저수위2식은 수문 완전폐쇄, 저수위3~6식은 수문 부분개방 곡선식을 개발하였으며, 저수위 구간은 낙양보 운영에 따라 총 27차례 기간분리가 발생하였다. 결과적으로 본 연구에서는 낙양 보 운영에 따른 다수의 유량측정성과와 모니터링 자료를 확보하였으며, 확보한 유량측정성과의 분석을 통한 신뢰도 높은 수위-유량관계곡선식을 개발하였고 이를 통해 생산된 유량자료는 정확도가 매우 높은 것으로 분석되었다.

• Journal of Veterinary Science
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• v.24 no.2
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• pp.24.1-24.13
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• 2023

Background: Ergothioneine (EGT) is a natural amino acid derivative in various animal organs and is a bioactive compound recognized as a food and medicine. Objectives: This study examined the effects of EGT supplementation during the in vitro maturation (IVM) period on porcine oocyte maturation and subsequent embryonic development competence after in vitro fertilization (IVF). Methods: Each EGT concentration (0, 10, 50, and 100 μM) was supplemented in the maturation medium during IVM. After IVM, nuclear maturation, intracellular glutathione (GSH), and reactive oxygen species (ROS) levels of oocytes were investigated. In addition, the genes related to cumulus function and antioxidant pathways in oocytes or cumulus cells were investigated. Finally, this study examined whether EGT could affect embryonic development after IVF. Results: After IVM, the EGT supplementation group showed significantly higher intracellular GSH levels and significantly lower intracellular ROS levels than the control group. Moreover, the expression levels of hyaluronan synthase 2 and Connexin 43 were significantly higher in the 10 μM EGT group than in the control group. The expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and NAD(P)H quinone dehydrogenase 1 (NQO1) were significantly higher in the oocytes of the 10 μM EGT group than in the control group. In the assessment of subsequent embryonic development after IVF, the 10 μM EGT treatment group improved the cleavage and blastocyst rate significantly than the control group. Conclusions: Supplementation of EGT improved oocyte maturation and embryonic development by reducing oxidative stress in IVM oocytes.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.3
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• pp.99-111
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• 2017

The purpose of this study is to provide a design and operation technical guideline for meeting the appropriate design criteria to bio-gasification facilities treating organic wastes. Based on the results obtained during the field surveys, the overall design and operation guidelines for bio-gasification facilities, monitoring items, cycle and commissioning period were presented. According to the flow of anaerobic digestion process, Various design factors for bio-gasification facilities were proposed in this study. When designing the initial anaerobic digestion capacity, 10 ~ 30% of the treatment capacity was applied considering the discharge characteristics by the incoming organic wastes. At the import storage hopper process, limit concentration of transporting organic wastes was limited to TS 10 % or less, and limit concentration of inhibiting factor was suggested in operation of anaerobic digester. In addition, organic loading rate (OLR) was shown as $1.5{\sim}4.0kgVS_{in}/(m^3{\cdot}day)$ for the combined bio-gasification facilities of animal manure and food wastes. Desulfurization and dehumidification methods of biogas from anaerobic digestor and proper periods of liquifization tank were suggested in design guideline. It is recommended that the operating parameters of the biogasification facilities to be maintained at pH (acid fermentation tank 4.5~6.5, methane fermentation tank 6.0~8.0), temperature variation range within $2^{\circ}C$, management of volatile fatty acid and ammonia concentration less than 3,000 mg/L, respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.43-52
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• 2006

Numerical model tests are done in order to evaluate impact zone of low salinity water on outer region of the developing Saemankeum reservoir. Also saline mixing processes are investigated f3r the inner reservoir with consideration of Mankyoung and Donjin riverine flood discharges when sea water is passing freely through gate. In these analyses 2-d ADCIRC, 3-d TIDED3D and CE-QUAL-ICM models are used. Through models tests, it is found that inner reservoir mixing process caused by inflow of outer sea water occurs gradually. It takes at least one month for complete mixing on Mankyoung part and 6 month on Dongjin part of the reservoir. When Sinsi or Garyeok gates are opened to control inner reservoir level, discharging velocities decrease exponentially from the gates, but show very strong currents of 0.5m/sec to the 10Km region apart. These results imply that hydrodynamic circulation and ecosystem of frontal region of the Saemankeum dike might be affected in amount by gate operations, since low saline inner waters are discharged periodically at ebb tide according to tidal level.

• Korean Journal of Environmental Agriculture
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• v.25 no.1
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• pp.34-39
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• 2006

The land use pattern, water quality and vegetation were investigated in the six tributaries, including Hanggeumcheon and Satancheon of the Namhan hydrosphere, Iksancheon, Jeonjucheon and Gosancheon of the Mankyung hydrosphere as well as Jongeupcheon of the Dongjin hydrosphere. Forest and farmland area were extensive in Hanggeumcheon, Satancheon and Gosancheon. Farmland and livestock area were wide in Iksancheon. Jeonjucheon were occupied with broad urban. Industrial and urban area were extensive in Jongeupcheon. The loading amounts of biochemical oxygen demand (BOD), total nitrogen (T-N), total phosphorus (T-P) of Iksancheon and chemical oxygen demand (COD) of Jeonjucheon were determined to be very high, respectively. The quality of water in Hanggeumcheon, Satancheon and Gosancheon were determined to be good quality. The species diversity was lower in the down stream than in the upper stream except for the Gosancheon. Life form of plane were mostly perennial plane in the upper stream and annual plants in the down stream of rivers. It was estimated that there is high level of disturbance in the down stream of rivers. The quality of water was significantly correlated with farmland and forest area. In conclusion, human impact, such as farmland and housing lot exerted an influence on the disturbance of down stream and the water quality of rivers.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.6
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• pp.557-566
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• 1993

For the purpose of examining the distribution of organic matter in the nearshore surface sediments of Korea, organic carbon, nitrogen, ignition loss, chemical oxygen demand, phaeopigment and total sulphide for 117 surface sediments were measured and analyzed in February, 1993. Organic carbon and nitrogen contents ranged from $0.03\%\;to\;5.41\%$ (average $1.08\%$) and from $0.01\%\;to\;0.44\%$ (average $0.18\%$), respectively. The highest contents with the average $2.18\%$ organic carbon and $0.23\%$ nitrogen were found in the eastern part of the southern coast, while the lowest contents with the average $0.17\%$ organic carbon and $0.03\%$ nitrogen in Kunsan coastal area covering from Kum river to Dongjin river. The principal component analysis using all measured data distinguished the western coast from the eastern part of the southern coast clearly according to organic matter contents, that is, the degree of eutrophication in the sediments. Pusan harbor and the mouth of Masan Bay had high C/N ratio that might be resulted from the input of terrestrial sewage and industrial wastewater. A high concentration of total sulphide distinguished the surface sediment of Masan Bay from that of other areas.