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정승현,정병곤,Jeong, Seung Hyun,Jeong, Byung Gon 한국물환경학회 2005 한국물환경학회지 Vol.21 No.6
In order to treat leachate from aged landfill site effectively, removal of biologically recalcitrant organic matter and denitrification efficiency were evaluated through the combination of $H_2O_2/O_3$ AOP pretreatment process and UASB process. The results can be summarized as follows. In case of leachate having low COD/N ratio from aged landfill site, it is possible to increase available COD for denitrification in nitrate utilizing denitrification and nitrite utilizing denitrification both by enhancing biodegradability of recalcitrant organic matter as applying $H_2O_2/O_3$ AOP to pretreatment process. In this experiment, it is found that available COD for denitrification can be increased to 1.0 and 0.4 g/day, respectively. Comparison has been made between requiring COD and available COD for denitrification in each experimental stages. It is expected that high rate of denitrification can be achieved with leachate from young landfill site because higher amount of available COD for denotrification is present in the leachate than the amount of requiring COD for denitrification. Especially, In leachate from aged landfill site with low COD/N ratio, it can be concluded that denitrification using nitrite nitrogen can enhance overall denitrification performance efficiently because denitrification using nitrite nitrogen requires less amount of carbon source than denitrification using nitrate nitrogen. Comparing the biogas production rate and nitrogen content of biogas under the condition of same amount of nitrate and nitrite addition, biogas production and nitrogen content of biogas are increased during denitrification after $H_2O_2/O_3$ AOP pretreatment process. Therefore, it can be confirmed that COD/N ratio in the leachate is increased. Applying $H_2O_2/O_3$ AOP as pretreatment system of landfill leachate seems to have little economic benefit because it requires additional carbon source to denitrify ammonia nitrogen in leachate coming from aged landfill site. However, it is possible to apply this pretreatment process to leachate from old landfill site in view of AOP process can achieve removal of biologically recalcitrant organic matter and increase of available COD for denitrification simultaneously.
외란 관측기를 이용한 중앙 분산형 다두 자수기의 동기제어
정승현(Seung Hyun Jeong),최득성(Deuk-Sung Choi),박정일(Jung Il Park) Korean Society for Precision Engineering 2014 한국정밀공학회지 Vol.31 No.11
This paper proposes the center distributed embroidery machine structure with 1,500 RPM, 52 heads for productivity and large sized embroidery goods. The synchronous velocity controller is adopted for control of the 2-axis distributed embroidery machine and the DOB(Disturbance Observer) is also adopted for minimizing disturbances caused by needle cams. For driving experiments of 2-axis center distributed driving structure, two conventional 26 heads 1,500RPM embroidery machines are used. It was shown that the center distributed driving structure with 2-axis synchronous control can be one way for implementing a large embroidery machine.
MMBT-S : 공간관계에 의한 검색을 지원하는 다차원 공간 접근 방법
정승현(Seung-Hyun Jeong),김종훈(Jong-Hoon Kim),김재홍(Jae-Hong Kim),배해영(Hae-Young Bae) 한국정보과학회 1997 정보과학회논문지(B) Vol.24 No.5
지리 정보 시스템이나 CAD(Computer Aided Design) 등과 같은 데이타베이스의 새로운 응용분야에서 시스템의 성능을 향상시키기 위해서는 공간 객체를 효율적으로 처리해야 한다. 따라서 데이타베이스 관리 시스템은 객체들간의 공간적 관계에 따라 원하는 정보를 빠르게 얻을 수 있는 접근 방법을 요구한다. 기존의 공간 데이타 접근 방법들은 객체들이 공간에서 차지하는 영역들간의 포함이나 겹침의 관계를 이용하는 기법으로서 영역 관계에 따른 검색에는 적합하지만, 거리, 방향 등의 다양한 공간 관계를 이용한 검색에 적용하기가 어렵다는 단점을 가지고 있다. 본 논문에서는 공간 객체들간의 영역 관계뿐만 아니라 거리, 방향 등과 같은 공간 관계를 이용하여 원하는 정보를 빠르게 검색할 수 있도록 하기 위해서 공간을 구성하는 각 좌표축들을 기준으로 공간 객체의 좌표값들의 집합을 이용하는 기법으로서 MMBT-S를 제안하였다. 좌표값 집합으로 색인을 구성하는 MMBT-S는 여러 가지 공간 관계를 이용한 다양한 형태의 검색을 할 수 있으므로 복잡하고 다양한 공간 질의를 위한 공간 색인 기법으로 이용될 수 있다. 또한 MMBT-S는 다차원 공간을 보다 쉽게 표현할 수 있을 뿐만 아니라 시공간과 같이 이질적인 성질을 갖는 다차원 영역에 대해서도 응용될 수 있다. In order to handle data efficiently in new applications of database such as CAD(Computer Aided Design) and geographic information system, database management system(DBMS) needs the access method which is able to retrieve data items quickly according to a spatial relation between them. The existing spatial access methods which are based on a relation between areas containing spatial objects, they are covered or overlapped each other, is proper to retrieval of data items by the relation of region. However, the access to spatial object by other spatial relations such as distance or direction cannot be supported by previous methods sufficiently and naturally. In this paper, we suggest an efficient spatial access method named MMBT-S which is able to support retrieval by the relation not only of region but also of distance and direction, Since it is based on the set of coordinates of which spatial objects consist, MMBT-S is able to support various complex spatial accesses. Also, it can handle multi-dimensional space easily, and be applied to a heterogeneous multi-dimension such as time-space dimension.
병원폐수의 전기화학적 처리시 무기응집제 주입 효과에 관한 연구
정승현(Seung Hyun Jeong),정병곤(Byung Gon Jeong) 大韓環境工學會 2011 대한환경공학회지 Vol.33 No.10
전해질 농도가 낮은 병원폐수를 전기화학적으로 처리할 경우 무기응집제 주입 효과에 대해 고찰한 결과, 무기응집제주입으로 전해질 농도가 높아져 병원폐수 내 유리염소의 농도의 증가로 유기물질의 간접산화효과가 증가하여 전류밀도 1.76 A/dm2, 반응시간 120분에서 무기응집제를 주입하지 않은 경우보다 COD 제거효율이 약 2배 향상되었다. 또한, 무기응집제에 의한 전해질의 증가로 HOCl과 같은 유리 잔류염소의 증가로 병원폐수 내의 클로라민이 질소로 전환되는 속도가 증가함에 따라 전류밀도 1.76 A/dm2, 반응시간 120분 및 응집제 주입량 700 ppm에서 T-N 제거율을 약 2배 향상시킬 수 있었다. 동일조건에서 90% 이상의 높은 T-P 제거율을 얻을 수 있었는데, 이는 무기응집제에 의한 전해질의 증가로 양전극에서의 발생되는 용존산소에 의해 생성된 불용성 금속 화합물과 인산염의 화학적 흡착반응 속도가 증가하였기 때문인 것으로 판단된다. 이상의 실험에서 전해질이 부족한 병원폐수의 전기화학적 처리시 무기응집제를 전해질로 첨가할 경우 유기물질 및 영양염 제거에 모두 매우 효과적임을 알 수 있었다. Effect of inorganic coagulants dosing on the performance of electro-chemical process was studied when treating hospital wastewater having low electrolyte concentration. It is thought that adding inorganic coagulants caused increase in concentration of electrolyte and this caused increase in free chloride concentration and consequently, caused increase in indirect oxidation effect. Thus, COD removal efficiencies more than doubled in percentage terms at the 2 hrs of reaction time and current density of 1.76 A/dm2 compared with the results obtained from the parallel experiments without adding inorganic coagulants. T-N removal efficiencies approximately doubled in percentage terms at the 2 hrs of reaction time and 700 ppm of coagulants addition and applied current density of 1.76 A/dm2 due to the increase of free residual chlorine such as HOCl caused by increase of electrolyte concentration through the addition of inorganic coagulants. Under the same experimental condition, more than 90% of T-P removal efficiencies was obtained. The reason can be explained that increase of chemical adsorption rate between phosphate and insoluble metal compounds caused by dissolved oxygen generated from anode by the increased electrolyte concentration through inorganic coagulants addition make a major role in improving T-P removal efficiencies. It can be concluded that inorganic coagulants addition as the supplemental agent of electrolyte is effective way in improving organic and nutrient salt removal efficiency when treating hospital wastewater having low electrolyte concentration.
오존산화가 매립지 침출수내 용존성 유기화합물의 생분해도에 미치는 영향
정승현 ( Seung Hyun Jeong ),정병곤 ( Byung Gon Jeong ) 한국물환경학회 2005 한국물환경학회지 Vol.21 No.1
The effect of ozone oxidation on biodegradability of leachate was studied. Ozone oxidation process was used as pre-treatment process to enhance performance of biological process in treating landfill leachate. Optimum ozone dosing rate and contact time in this experiment was 160 mg O₃/L hr and 45 minutes, respectively. Biodegradability was enhanced 5.08% by ozone oxidation. The ratio of ozone demand/DOC concentration was 0.049~0.091 mg O₃/mg DOC. The increase of biodegradability depending on ozone dosing rate(D) and contact time(T) can be expressed as follows ; ΔE=0.00479?D^(0.773)?T^(0.800) The biodegradation rate of DOC was increased proportionally with the increase of ozone dosing rate and contact time irrespective of landfill site age. The increase of biodegradability by ozone addition was not satisfactory. It is hard to expect significant increase in biodegradability by ozone treatment only. Thus, it is evaluated that ozone oxidation can not increase biodegradability significantly in concentrated wastewater composed of complex organic compound such as leachate.