• 한국농공학회지
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• 제39권2호
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• pp.97-103
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• 1997

DO concentration in the aquatic system is important for the water quality management perspective. Water quality model uses available reaeration coefficient (K2) estimation equations in calculating DO, however, they might include inevitable uncertainty that the model output can be less reliable. In this study, the calibrated QUAL2E model for the Passaic River in New Jersey, U.S., was used to examine the effect of K2 estimation equation on the output DO concentration of the river. The model was run with six commonly used equations separately with all the other conditions remained same. The result showed that the output DO concentration profiles varied widely with different equations, and maximum difference was 4.96 mg/L for the same location which is unacceptably large. It implies that the development of reliable equation is required for proper water quality management. The unreliable model output can lead to a wrong decision in water quality management such as unnecessarily high or too low treatment of wastewater, which will cause serious effect on the community economically and socially in either case. Generating more reliable model output with slight investment to develop a site specific K$_2$ equation can improve the decision making process significantly and is highly recommended.

• 한국대기환경학회지
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• 제28권6호
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• pp.666-674
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• 2012

The purpose of this study is to propose management strategies to lower the level of $PM_{10}$ concentration. First, this study analyzes the characteristics of particle sizes in three different areas, the residential, the roadside, and the industrial areas. Second, it has examined the size of particles which can influence on the increase of $PM_{10}$ concentration level. The distribution of particle size for $PM_{10}$ concentration was not different by regions. The highest portion in the observed $PM_{10}$ is near $0.3{\mu}m$. In addition, both near $2.5{\mu}m$ and near $5.0{\mu}m$ are found higher in portion. The fractions of $PM_{1.0}$ and $PM_{2.5}$ in $PM_{10}$ are 68.2% and 75.8% respectively. The fraction of $PM_{1.0}$ in $PM_{2.5}$ is 89.8%. The particle diameters contributed to the increase of $PM_{10}$ concentration are different by regions. In the residential area, the sizes of near $0.6{\mu}m$ and near $3.3{\mu}m$ particles are found to be the cause for the increase of $PM_{10}$ concentration level. However the particle sizes for the increase of $PM_{10}$ concentration level are $0.8{\mu}m$ and $0.5{\mu}m$ in roadside and industrial area respectively. Therefore, fine particles are found as the key factors to raise $PM_{10}$ concentration level in the two areas, while both fine and coarse particles are in the residential areas. When examined the $PM_{10}$ concentration level change, it was categorized by two different time zones, the high concentration level time and the lower concentration time. In high concentration time, the $PM_{10}$ concentration has increased in the morning in the residential and roadside areas. On the contrary, the level has increased in the evening in the industrial area. In low concentration time, the level of $PM_{10}$ concentration in the roadside area is significantly higher in the morning than the concentration level of other times. There is no significantly different concentration level found in the both residential and industrial areas throughout the day.

• 한국환경농학회지
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• 제18권4호
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• pp.339-343
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• 1999

추석용으로 출하하고 있는 단감 `서촌조생`의 조기 수확을 위하여 착색증진용 생장조절물질인 에세폰의 적정농도를 구명코자 본 연구를 수행한 결과를 요약하면 다음과 같았다. 에세폰 적정농도 설정에서 에세폰을 고농도인 30∼40㎎/l로 처리하면, 과피색도가 증가하나 과육경도 및 연화과발생율이 많았고 또한 유통한계기간도 짧아 상품성 유지가 어려웠다. 반면 저농도인 10∼20㎎/l에서는, 과피색도, 과육경도, 연화과발생율 및 유통한계기간 등 모든 면에서 상품성이 높게 유지되었다. 그리고, 에세폰 처리에 의해 조기 수확한 과실의 가용성고형물 함량은 일반적인 수확기의 그것에 비해 매우 낮았는데, 가용성고형물 함량도 동시에 증가시킬 수 있는 연구가 앞으로의 과제라 하겠다.

• 한국대기환경학회지
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• 제34권3호
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• pp.486-492
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• 2018

Black carbon concentrations were measured along the altitude at various locations using a drone coupled with a small black carbon detector. The measurement locations are Eunseok Mountain, downtown, four places in KOREATECH campus, Byeongcheon, Cheonan, Chungcheongnam-do, and Chungbu Expressway in Ochang-eup, Cheongju, Chungcheongbuk-do. The average concentration of black carbon measured in Eunseok Mountain was $1.64{\mu}g/m^3$ and the average concentration near the Chungbu Expressway was measured to be $3.86{\mu}g/m^3$. The average concentrations of four places inside campus ranged from 1.37 to $2.67{\mu}g/m^3$. The concentration of black carbon at all places tended to be slightly decreased according to the altitude, but the influence of pollution source, geometry, wind speed, and wind direction are thought to be larger than the effect of altitude. Effect of air flow caused by drone flight on the measurement of black carbon were investigated and it resulted in that the measurement of BC concentration was affected by less than 5%.

• 수산해양기술연구
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• 제51권2호
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• pp.155-162
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• 2015

Abalone (Haliotis discus hannai) is a shellfish that feeds on kelp and, as a product, it can often achieve a high market value. However, the dissolved oxygen (DO) levels in coastal waters in Korea have been negatively impacted by pollution from many anthropogenic sources. Herein, a computational fluid dynamics (CFD) software package was used to analyze the distribution of the DO concentration within an abalone containment structure. A finite volume approach was used to solve the Reynolds-averaged Navier-Stokes equations combined with a $k-{\varepsilon}$ turbulence model to describe the flow. The distribution of DO was determined within the control volume domain, and the transport equations of the pollutants were interpreted using a CFD model. The CFD analysis revealed that more than 60% and 30% of the relative oxygen concentration in one and two containers, respectively, was maintained when the flow acts along the six sheets of polyethylene plates. Therefore, it is clear that the abalone plate shelters should be placed parallel to the flow.

• 한국환경농학회지
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• 제22권4호
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• pp.241-245
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• 2003

This study was carried out to evaluate the status of the groundwater quality for paddy fields irrigation in Korea. Water samples were collected at 130 sites throughout the country. Samples were collected at three seasons - April, July and October - in 2000. According to our survey, the groundwater was found to be suitable for irrigation purpose. Average EC was shown 0.286 dS/m. Nitrate-nitrogen and $Cl^-$ concentration was 5.6 mg/L, 32.95 mg/L which satisfied the Korean Standards for Irrigation Water. Nitrate-nitrogen concentration in each province was shown as following orders: Jeju (11.17 mg/L) > Chungnam (8.16 mg/L) > Gyeongbuk (6.64 mg/L) > Gyounggi (5.91 mg/L) > Chungnam (4.95 mg/L) > Gyeongnam (3.91 mg/L) > Jeonbuk (3.50 mg/L) > Jeonnam (3.27 mg/L) > Gangwon (2.91 mg/L). The concentration by sampling seasons were October (6.62 mg/L) > July (5.88 mg/L) > April (4.78 mg/L). As the soil of Jeju Province is usually derived from volcanic ash soils mainly used for upland drops, it may influence the nitrate-nitrogen concentration of groundwater. The amount of rainfall also influence the water quality. But the $COD_{Cr}$ were shown April (3.17 mg/L) > July (2.91 mg/L) > October (2.40 mg/L), it is highly related in the basal dose of organic matter fertilizers. This study demonstrated that groundwater quality was suitable for irrigation, but continuous monitoring is recommended for agricultural policy and developing OECD agricultural environment indicators.

• 한국수산과학회지
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• 제34권3호
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• pp.190-193
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• 2001

바지락의 용존산소 농도에 따른 SFG (Scope for growth)의 변화를 알아보기 위하여 수온 $23\pm0.5^{\circ}C$와 일반해수에서 반수치사농도, 여수율, 호흡률, 암모니아 질소배설률 및 동화효율 등을 측정하였다. 바지락의 용존산소 농도의 감소에 따른 $LC_{50}$은 2.4mgDO$L^{-1}$였다. 여수율과 호흡률은 실험용액의 용존산소의 감소에 따라 대체로 감소하는 경향을 보인 반면, 암모니아 질소 배설률은 용존산소의 감소에 따라 증가하였다. 동화효율은 6.5mgDO $L^{-1}$에서는 $68.2\%$였으며, 3.5 mgDO $L^{-1}$ 이하의 농도에서는$29.8\~39.3\%$로 차이를 나타내지 않았다. 용존산소의 농도에 따른 SFG는 2.5mgDO $L^{-1}$ 이상에서는 양의 값을 나타내어 생존 및 성장이 가능한 것으로 나타났다.

• Environmental Analysis Health and Toxicology
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• 제6권3_4호
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• pp.155-161
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• 1991

The water quality in Wonju stream, Seom river in Kangwon province and Bokha, Shindun stream in Kyeonggi province was investigated between the season of irrigation on July, 1990 and of non-irrigation on September in 1989. The results of water quality obtained from this study were as follows; As for water quality of the Wonju stream and the Seom river, the concentration of COD, T-N, SS and Cu, and for the Bokha, Shindun stream, the concentration of T-N, SS and Cu were exceeded standard levels of quality guideline of agricultural water use in the season of irrigation. However, in the water quality of Wonju and Bokha stream, the concentration of T-N , SS and Cu, and in the Seom river, the concentration of T-N, SS, Cu and Zn were exceeded standard levels of agricultural water quality in the season of non-irrigation. And the average water quality of the 4 streams were not suitable for agricultural water use. The comparison of the annual average water quality of the 4 streams for pH, DO, T-N and SS were in statistics significantly different with p values less than 0.01. When the average water quality between the season of irrigation and non-irrigation in each stream was compared, DO and COD in the Wonju stream, COD in the Seom river, pH, DO, T-N, SS and Cu in the Shindun stream showed a significant difference with p<0.01. The average in the sediment were; COD, 5.65∼26.53 ppm; Cu, 0.26∼0.49 ppm and Zn 0.95∼2.97 ppm. The concentration of three contaminants were markedly higher than the water quality. And the concentration of COD, Zn in the sediment showed a significant difference with p<0.01, and Cu showed a considerably significant difference with p<0.05.

• 한국버섯학회지
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• 제21권3호
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• pp.160-166
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• 2023

표고 신품종 '자담'의 자실체 안정생산을 위해 침공처리가 균사배양 및 자실체 생산성에 미치는 영향을 조사하였다. 침공 직경과 깊이가 크고, 침공수가 많을수록 중량감 모율과 색차는 증가하고 명도는 감소하였다. 종균 접종 후 배지온도는 배양 33일에, CO₂농도는 배양 19일에 최고치에 도달하였고, O₂농도는 CO₂ 와 반대의 경향으로 배양 14일에 최저치를 나타냈다. 침공 직경과 깊이가 크고 침공수가 많을수록 배지 품온과 O₂농도는 상승하였고, CO₂농도는 낮아졌다. 수량성은 5×70 mm-30 처리구에서 644.7 g으로 다른처리구에 비해 가장 높은 수량을 보여 자담의 적정한 침공방법으로 선발하였다.

• 한국대기환경학회지
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• 제17권1호
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• pp.19-29
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• 2001

Atmospheric concentrations of acidic pollutant were measured by the 4 stage filter pak method at Chunchon and by the 3 stage filter pack method at Seoul and Anmyon-do from January to December 1998. The sample was collected for 24 hours on every Wednesday. Concentrations of particulate matters were highest at Anmyon-do. The particulate concentration was much higher during the warm season than other seasons. While the particulate concentration was higher during the warm season, the concentration of gaseous matter was higher in winter. Dry deposition flux was calculated by using reported deposition velocities and concentration of pollutants measured in this study. The dry deposition velocities used in this study for SO$_2$, SO$_{4}^{2}$, HNO$_3$,NO$_{3}^{-}$ and NH$_3$ were 0.29, 0.15, 2.08( 2.13 only for Anmyon-do), 0.20 and 1.00cm/sec, respectively. At Chunchon, annual sulfur flux originated from dry deposition was 384 kg/$textrm{km}^2$, and the flux from wet deposition was 782kg/$textrm{km}^2$. Dry deposition of sulfur was 33% of total sulfur deposition. The annual nitrogen flux originated from dry deposition was 1,892kg/$textrm{km}^2$. And the flux from wet deposition was 1,066kg/$textrm{km}^2$. Dry deposition of nitrogen was 64% of total nitrogen deposition. Dry deposition as well as wet deposition have to be considerd in the study on acidification of environment such as soil or watershed.