• 상하수도학회지
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• 제19권3호
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• pp.348-356
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• 2005

Water quality sampling surveys and continuous measurement of flow were conducted to identify wastewater flow characteristics for representative catchment of O and M treatment basins in A city. For HS-1 station representing commercial area, wastewater flow rises in the beginning of office-working hours, moves up and down within narrow range, and lasts till office-leaving hour, and falls gradually reflecting worker's returning home. However, in HS-2 station representing residential area, wastewater flow has two peaks, which are before office-going hour and after office-leaving hour. In residential area, the flow rate of weekends is higher than that of weekdays because it reflects population, being not contributed to generate wastewater during the working hours of weekdays, stay home and produce wastewater for weekends period. To determine the priority for rehabilitation of sewer system, infiltration rate was computed by dividing infiltration flow by mean diameter and total length of sewer, and HS-1 station ranked the first.

• Environmental Engineering Research
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• 제24권1호
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• pp.107-116
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• 2019

Nitrogen removal, nitrous oxide ($N_2O$) emission and microbial community in sequencing batch and continuous-flow intermittent aeration processes were investigated. Two sequencing batch reactors (SBRs) and two continuous-flow multiple anoxic and aerobic reactors (CMRs) were operated under high dissolved oxygen (DO) (SBR-H and CMR-H) and low DO (SBR-L and CMR-L) concentrations, respectively. Nitrogen removal was enhanced under CMR and low DO conditions (CMR-L). The highest total inorganic nitrogen removal efficiency of 91.5% was achieved. Higher nitrifying and denitrifying activities in SBRs were observed. CMRs possessed higher $N_2O$ emission factors during nitrification in the presence of organics, with the highest $N_2O$ emission factor of 60.7% in CMR-L. SBR and low DO conditions promoted $N_2O$ emission during denitrification. CMR systems had higher microbial diversity. Candidatus Accumulibacter, Nitrosomonadaceae and putative denitrifiers ($N_2O$ reducers and producers) were responsible for $N_2O$ emission.

• Journal of Electrochemical Science and Technology
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• 제13권2호
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• pp.261-268
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• 2022

In this study, electrochemical treatment of urban wastewater with electrical conductivity of 1000 μS cm^-1 and chemical oxygen demand of 250 mg L^-1 was investigated using the variables of initial pH value, current density and flow rate. Electrocoagulation was used, in which aluminum and stainless steel were selected, as the electrochemical treatment process. The electrocoagulation process was operated in continuous mode. The data obtained in experimental studies show that the best COD removal efficiency occurred in experiments where the initial pH value was 6. The increase in current density from 5 A to 15 A decreased the removal efficiency from 79 to 67%. The increase in flow rate under constant current density also reduced the efficiency of removal as expected. In experiments in which current density and flow rate were examined together, the increase in flow rate allowed the application of higher current densities. This situation led to considerable reductions in energy consumption values, even if the COD removal efficiency did not significantly increase. The high COD removal obtained with the use of high flow rate and high current density indicates that the electrocoagulation process can be used for high flow rate municipal wastewater treatment.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 추계학술대회
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• pp.427-429
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• 2022

최근 메타버스 기술은 게임, 엔터, 제조, 유통, 광고, 교육 등 다양한 서비스 산업에서 활용되고 있다. 메타버스 콘텐츠에 사용되는 디바이스의 지속이용 상관관계 연구는 아직 미흡한 상태다. 메타버스에 더욱더 몰입할 수 있게 자연스러운 움직임과 사용하기 편한 입력장치 계발이 필요하다. 플로우를 기반으로 메타버스 콘텐츠와 디바이스의 지속이용에 관한 주제로 연구하였다. 독립변수인 Flow의 구성 요인을 현실감, 몰입감, 상호작용으로 설정하였다. 설문조사 기관을 통해 500명의 메타버스 남녀 이용자들의 자료를 연구에 활용하고자 한다. 메타버스 콘텐츠와 디바이스의 지속이용을 높이는 플로우 요인 중 가장 큰 영향력으로 작용하는 요인이 무엇인지를 연구하였다. 본 연구 결과를 통하여 차세대 메타버스 콘텐츠와 디바이스 산업의 방향성 수립에 도움이 되고자 한다.

• International Journal of Aeronautical and Space Sciences
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• 제16권2호
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• pp.148-156
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• 2015

A continuous type side jet controller which has four nozzles with thrust control devices was considered. It is deployed to a missile for high maneuverability and fast controllability in the terminal guidance phase. However, it causes more complex aerodynamic jet interactions between the side jet and the supersonic free stream than does the conventional impulse type side jet with a small single thruster. In this paper, a numerical investigation of the jet interference effects for the missile equipped with a continuous type side jet thruster is presented. A three-dimensional flow field was simulated by using a commercial unstructured-based CFD solver. The numerical simulation method was validated through comparison with wind tunnel test results for the single jet. The method of defining jet direction for this type of side jet control to minimize simulation cases was also introduced. Flow fields investigation and jet interaction effects for various flow conditions, jet pressure ratios and defined jet direction conditions were performed. From the numerical simulation for the continuous type side jet, extensive aerodynamic interference data were obtained to construct an aerodynamic coefficients database for precise missile control.

• 유통과학연구
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• 제20권10호
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• pp.105-117
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• 2022

Purpose: The digital healthcare business is rapidly growing due to the COVID-19 pandemic, and the medical service platform business based on smartphone apps is globally expanding. This study targeted medical information online to offline (O2O) platform users in the medical service field. It verified the effect relationship revealed in the continuous use intention of the platform with the mediation of platform quality components, namely perceived benefits, flow experience, and use satisfaction. Research design, data and methodology: Based on previous studies, three medical information O2O platform quality components, namely system quality, information quality, and service quality, were defined. And the questionnaire survey was carried out targeting 359 leading medical information O2O platform users in Korea. Results: As a result of the analysis, it was confirmed that system quality and service quality had a positive (+) effect on satisfaction and continuous use intention with the mediation of perceived benefits and flow experience. Meanwhile, information quality had a negative effect (-) on perceived benefits and flow experience and did not affect use satisfaction and continuous use intention. Conclusions: Consequently, it was ascertained that the system quality and service quality affecting user behavior and experience were more significant factors than information quality to medical information O2O platform users from the medical service aspect.

• 대한수학회보
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• 제40권4호
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• pp.703-713
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• 2003

We extend the notion of inverse shadowing defined for diffeomorphisms to flows, and show that an expansive flow on a compact manifold with the shadowing property has the inverse shadowing property with respect to the classes of continuous methods. As a corollary we obtain that a hyperbolic flow also has the inverse shadowing property with respect to the classes of continuous methods.

• 통상정보연구
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• 제17권3호
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• pp.29-57
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• 2015

본 연구는 SNG 사용자의 지속적인 게임몰입으로 인한 중독에 영향을 미치는 동기요인들이 무엇인지 살펴보고자 한다. 본 연구는 SNG의 특성에 접근성, 재미성, 보상을, 사용자의 특성에 자기효능감, 자기통제력, 도전감을, 환경적 특성에는 사회적 상호작용, 주관적 규범, 커뮤니티를 제안하고 지속적 게임몰입에 미치는 영향과 나아가 SNG 중독에 미치는 영향을 연구하고자 한다. SNG 사용자 대상으로 374명으로부터 데이터 수집하여 구조방정식 접근방법을 통해 제안된 연구모형을 분석하였다. 연구결과에 따르면 자기효능감과 도전감, 그리고 커뮤니티를 제외한 나머지 변수들은 모두 지속적 게임몰입에 영향을 주며, 중독까지 영향을 미치는 것으로 나타났다. 본 연구내용은 SNG 중독에 새로운 이론적 프레임워크를 제안하고 실무적으로도 중요한 해결책을 제시할 수 있다.

• KSBB Journal
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• 제5권1호
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• pp.59-67
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• 1990

생성물의 분리 및 효소의 회수를 위하여 수평흐름 한외여과장치를 부착한 기포탑에서 섬유소의 연속적인 효소 가수분해 반응을 연구하였다. 기포탑을 효소 가수분해 반응 공정에 이용할 경우 기체유속의 범위는 1-3cm / sec로 기포의 합체현상이 발생하지 않는 dispersed bubble flow 영역이 적합하며 혼합도 거의 완전하게 이루어짐을 확인하였다. 효소 회수장치에 한계분자량이 $10^4$인 여과막을 사용하였을 경우 효소의 활성이 저하되지 않은 채 대부분이 회수되었고 glucose 및 cellobiose의 배제율은 0이었다. 따라서 수평흐름 한외 여과장치는 효소의 연속회수장치로 작합하였으며 반응생성물이 연속적인 분리로 섬유소의 당화율을 증가시켰다. 화분식 반응의 경우 반응시간이 8시간이내에서 실험치는 성능식에 잘 부합되었으나 반연속식 및 연속식 반응의 경우에는 이론값과 차이가 있었다. 이는 반응기 내에서의 효소의 변성에 기인된다. 반연속식 및 연속식 반응의 경우 희석율을 증가시킴에 따라 전환율은 증가하나 반응액중의 환원당의 농도는 낮아진다. 따라서 적정한 기질 공급속도 및 희석율은 효소의 회수비용, 생성물의 농축비용 및 기질의 공급비용등의 경제적 요소를 고려하여 판단하여야 한다. 이상의 결과로부터 수평흐름 한외여과장치를 효소 회수장치로 기포탑에 응용할 경우, 효소의 재사용이 가능할 뿐 아니라 당화율을 증가시킴으로서 연속반응기로 효과적이라고 판단되었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.89-92
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• 2004

The influence of a single fracture intersection on density-driven immiscible flow is compared between wetting (water into air) and nonwetting (Trichloroethylene into water) flows. At low supply rates, the intersection acted as a hysteretic gate to pulsed flow of the wetting phase, but had minimal influence on nonwetting phase flow. For both cases, increasing the supply rate led to the formation of continuous fluid tendrils that crossed the intersection without interruption. The wetting experiment returned to pulsed flow as the supply rate was decreased, while the nonwetting experiment maintained a continuous flow structure. Results suggest a fundamental difference between wetting and nonwetting phase flows in fracture network.