• 한국해안해양공학회지
• /
• 제18권3호
• /
• pp.211-224
• /
• 2006

주문진항에서 2002년부터 2005년까지 월별로 관측한 COD, 총질소(TN), 총인(TP) 항목의 정점별, 계절별 변화 양상을 분석하였다. 전반적으로 상층의 오염도가 하층에 비하여 높게 나타났으며, 상층과 하층의 COD 및 TN, TP 항목 농도차이는 주문진항 내부영역이 방파제 전면해역에 비하여 크게 나타났다. COD 농도는 변화 폭이 시기에 따라 다르지만 계절별 변동양상이 뚜렷하고, 암모니아성질소 및 TN 항목도 계절별 변동양상이 뚜렷하게 나타난다. 지점별, 월별 자료를 영역별, 연도별로 평균하여 해수교환시설 및 하수종말처리시설의 수질개선효과를 정량적으로 분석한 결과, COD 항목은 2003년도에는 미미한 변화를 보이고 있으며, 2004년, 2005년에는 모든 영역에서 $34{\sim}47%$ 정도 COD 농도저하가 계산되었다. 또한, TN 항목도 해수교환 시설에 의한 영향이 우세한 것으로 판단되었다. 해수교환 시설이 TN 농도저하에 미친 영향은 영역 1, 영역 2, 영역 3 순서로 각각 $60{\sim}70%,\;40{\sim}60%,\;40%$내외 정도로 산정되었다. 따라서, 해수교환시설이 COD 및 TN 농도저하, 즉 수질개선에 미치는 영향은 주문진항 내부영역으로 국한되지 않고, 주문진항 입구 및 방파제 전면해역으로 확장되고 있는 것으로 판단된다.

• 한국해양공학회지
• /
• 제22권6호
• /
• pp.20-26
• /
• 2008

In this paper, in order to set up the management system of water quality environment in Gwangyang Bay, the cluster analysis of water quality environment, the estimation of inflowing pollutant loads and residence time of pollutants in this bay was carried out. The Gwangyang Bay was divided into eight sea areas by cluster analysis and spatio-temporal change of water quality. The river discharges in the Bay were calculated about $11,681{\times}103m^3/day$ from the numerical simulation by Tank model. In addition, inflowing pollutant loads of COD, SS, TN, TP, DIN and DIP in Gwangyang Bay were estimated at 398 ton-COD/day, 2,846 ton-SS/day, 195 ton-TN/day, 5 ton-TP/day, 126 ton-DIN/day and 3 ton-DIP/day, respectively. Moreover, residence times of COD, TN and TP in the Bay was estimated at 6 days-COD, 20 days-TN and 195 days-TP, respectively in the dry season, and 3 days-COD, 6 days-TN and 21 days- TP, respectively, in the flood season. The central part of Gwangyang Bay (Region IV) has the longest residence time of overall pollutants.

• 대한의용생체공학회:의공학회지
• /
• 제39권6호
• /
• pp.278-283
• /
• 2018

Nowdays, many people suffer from the neck pain due to forward head posture(FHP) and text neck(TN). To assess the severity of the FHP and TN the craniovertebral angle(CVA) is used in clinincs. However, it is difficult to monitor the neck posture using the CVA in daily life. We propose a new method using the cervical flexion angle(CFA) obtained from a wearable sensor to monitor neck posture in daily life. 15 participants were requested to pose FHP and TN. The CFA from the wearable sensor was compared with the CVA observed from a 3D motion camera system to analyze their correlation. The determination coefficients between CFA and CVA were 0.80 in TN and 0.57 in FHP, and 0.69 in TN and FHP. From the monitoring the neck posture while using laptop computer for 20 minutes, this wearable sensor can estimate the CVA with the mean squared error of 2.1 degree.

• 대한환경공학회지
• /
• 제30권6호
• /
• pp.666-672
• /
• 2008

수산물 가공폐수를 AO$_2$공법에 적용하여 유기물, 질소, 인의 동시제거 가능성을 평가 하였다. 처리도 실험은 도시하수처리장에서 가져온 활성슬러지를 담체에 2주 이상 부착시킨 후 반응조 부피 25%로 충진하여 실험을 행하였다. 유입수 농도는 실험기간 동안 COD : 198 - 1,240 mg/L, TN : 75 - 577.4 mg/L, TP : 2.2 - 53.5 mg/L였다. 운전기간동안 평균 제거효율은 COD : 86.5%(65.7 mg/L), TN : 81.4%(53.1 mg/L), TP : 80.6%(4.07 mg/L)로 나타났다. Anaerobic조와 Aerobic조로 구성된 시스템에 유기물 및 영양염류 부하율이 증가되어도 비교적 안정된 형태의 운전이 가능하였다. 사용된 PU-AC 메디아는 높은 MLSS량을 보유하여 AO$_2$ 시스템 내에서 생물학적 처리율을 높일 수 있었던 것으로 사료된다.

• 생태와환경
• /
• 제42권2호
• /
• pp.153-160
• /
• 2009

비점오염원으로부터 오염된 소하천에서 영양염류를 제거하기 위하여 식물플랑크톤 배양 장치를 설치하고 운영하였다. 식물플랑크톤 배양조에서 식물플랑크톤 정치배양 결과, 식물플랑크톤의 연속배양을 위한 배양조의 체류 시간을 3일로 결정하였으며 TP는 70%, TN은 44%가 제거됨을 확인하였다. 연속배양 결과 45일 동안 배양조에 유입된 TP의 53.9%, TN의 53.1%가 식물플랑크톤에 의한 흡수와 슬러지로 제거되었다. 식물플랑크톤이 성장하면서 배양조의 pH와 용존산소농도는 각각 평균 10.8, 16mg $L^{-1}$이었다. 결국 비점오염원에 오염된 하천수의 영양 염류는 식물플랑크톤의 사체와 화학반응으로 생성된 침전물로 제거되었다. 비교적 설치가 간단하고 경제성이 높은 식물플랑크톤 배양법의 높은 현장적용 가능성을 확인하였다.

• 한국환경복원기술학회지
• /
• 제13권1호
• /
• pp.82-92
• /
• 2010

Removal rates of NO3-N and TN in a free water surface wetland system during emergent plant growing season and non-growing were investigated. The system was established on floodplain in the down reach of the Gwangju Stream in 2008. Its dimensions were 46 meters in length and 5 meters in width. Typha angustifloria L. growing in pots about two years were planted on the half area of the system and Zizania latifolia Turcz on the other half. Water of the stream was funneled into it by gravity flow and its effluent was discharged back into it. Volumes and water quality of inflow and outflow were analyzed from October 2008 to September 2009. Inflow into the system averaged approximately 715 $m^3$/day and hydraulic residence time was about 1.5 hr. Average influent and effluent $NO_3$-N concentration was 3.37 and 2.74 mg/L, respectively and $NO_3$-N retention amounted to 18.7%. Influent and effluent TN concentration averaged 4.67 and 3.69 mg/L, respectively and TN abatement reached to 20.9%. $NO_3$-N removal rate (%) during plant growing season ($22.67{\pm}3.70$, mean ${\pm}$ standard error) was significantly high (p<0.001) when compared with that during plant non-growing one ($15.02{\pm}3.23$). TN abatement rate (%) during plant growing season ($27.42{\pm}5.98$) was also significantly high (p<0.001) when compared with that during plant non-growing one ($13.66{\pm}3.08$).

• 한국안전학회지
• /
• 제24권6호
• /
• pp.32-38
• /
• 2009

According to the statistics from the Ministry of labor, 70~80 people died by work-related electric shock accidents in the workplace and this number is about 10~20 times higher than those of the foreign countries such as Japan and the United Kingdom in frequencies and rates per 100,000. The electrocution deaths had decreased from several hundred in 1990s to 67 in 2002, since then there has been little change over the last 5 years. To reduce this number of the electrocution death, it is necessary to analyze the sources of the accidents and to implement the suitable measures for preventing the similar accidents from occurring. But there is not any consensus standard method or procedures for accident investigation yet. And the results solely depend on the ability of the investigator. Because of the demand of eliminating technical barrier for free trading, the IEC 60364 is adopted as a regulation for low voltage electrical installations in Korea. The facilities designed and constructed by IEC 60364 are increasing. The facilities by IEC 60364 have different features in comparison with the facilities by Korea eletro technical regulation, and these features combined with parameters of electric shock accident can greatly affect the consequences of the electric accidents. The accident analysis program for electric shock injuries in Terra Neutral(TN) and Terra Terra(TT) system was developed in this paper, which was based on KOSHA Electric Shock Analysis Program(ESAP).

• 상하수도학회지
• /
• 제20권1호
• /
• pp.94-103
• /
• 2006

The pollution in closing water can be caused by not only artificial factor like sewage but also natural factor like elution from sediment. In this study we analyzed Sediment Oxygen Demand (SOD) for verification of sediment purification effect and sediment elution experiment as well as general items like COD, TN, TP, SS to complement and assess the effect of sediment and water quality. The experiment result showed that the release rate of OSD system were 4 times and 3 times as large as control for P and Fe respectively. SOD for operated OSD system and control were $12.18gO_2{\cdot}m^{-2}{\cdot}d^{-1}$ and $47.95gO_2{\cdot}m^{-2}{\cdot}d^{-1}$. From water qualities analyzed by COD, TN, TP, SS, chlorophyll-a, the removal efficiency increase of TN, TP, chlorophyll-a and COD were about 10~20%, 40~50% and 10% respectively. In conclusion, OSD can contribute to improvement of both the waterbody and the sediment environment effectively.

• Environmental Engineering Research
• /
• 제17권1호
• /
• pp.41-46
• /
• 2012

In this study, the performance of new digestion system (NDS) for the treatment of food waste leachate was evaluated. The food waste leachate was fed intermittently to an anaerobic reactor at increasing steps of 3.3 L/day (hydraulic retention time [HRT] = 30 day), 5 L/day (HRT = 20 day), and finally 10 L/day (HRT = 10 day). In the anaerobic reactor, the pH and alkalinity were maintained at 7.6 to 8.2 and 8,940-14,400 mg/L, respectively. Maximum methane yield determined to be 0.686L $CH_4$/g volatile solids (VS) containing HRT over 20 day. In the digester, 102,328 mg chemical oxygen demand (COD)/L was removed to produce 350 L/day (70% of the total) of biogas, but in the digested sludge reduction (DSR) unit, only 3,471 mg COD/L was removed with a biogas production of 158 L/day. Without adding any chemicals, 25% of total nitrogen (TN) and 31% of total phosphorus (TP) were removed after the DSR, while only 48% of TN and 32% of TP were removed in the nitrogen, phosphorus, and heavy metals (NPHM) removal unit. Total removal of TN was 73% and total removal of TP was 63%.

• Journal of electromagnetic engineering and science
• /
• 제11권1호
• /
• pp.34-41
• /
• 2011

This paper proposes a systematic design for a precoding codebook for a transmit-ing space-division multiple access (TN-SDMA) sharing spectrum with existing fixed wireless service (FWS). Based on an estimated direction angle of a victim FWS system, an interfering transmitter adaptively constructs a codebook, forming a transmit in the direction angle, while satisfying orthogonal beamforming constraints. Sum throughput results indicate that the throughput loss of TN-SDMA relative to a practical SDMA, called per user unitary and rate control ($PU^2RC$), is lower at larger number of transmission antennas, lower signal-to-noise ratio, or a smaller number of users. In particular, a small loss (12% throughput loss) is provided for practical system parameters. Spectrum sharing results confirm that TNSDMA efficiently shares spectrum with FWS systems by reducing protection distance to more than 66 %. Although a TN-SDMA system always has lower throughput compared to $PU^2RC$ in non-coexistence scenarios; it offers an intriguing opportunity to re-use a spectrum already allocated to an FWS.