2020년 1월 1일부터 국제해사기구(IMO)는 전 세계 모든 해역을 지나가는 선박을 대상으로 선박연료유의 황 함유량 상한선을 3.5 %에서 0.5 %로 낮춰 선박으로 인해 발생하는 대기오염을 줄이기 위한 강력한 규제를 실시한다. 황 함유량이 낮은 연료유를 사용하여 대기오염 물질을 줄이는 것도 중요하지만 선박을 경제적으로 운영하여 불필요한 에너지 낭비를 줄이는 것 또한 대기오염 물질을 줄이는 데 큰 도움이 된다. 따라서 선박은 잡음의 영향을 받더라도 항로를 정확하게 유지하여야 한다. 항로를 정확하게 추종하기 위해 오토파일럿 시스템이 사용되지만 오토파일럿 시스템의 성능이 아무리 우수하다 하더라도 잡음의 영향을 받게 된다면 성능에 한계를 가진다. 실제 환경에서는 자이로스코프에서 측정잡음이 더해진 회두각이 오토파일럿 시스템의 입력으로 들어가 오토파일럿 시스템의 성능을 저하시킨다. 이와 같은 문제를 해결하기 위해 상태추정에 쓰이는 Kalman Filter를 적용하여 잡음의 영향을 줄여주는 기법이 있지만 이 또한 역시 잡음의 영향을 완전히 제거시키는 것이 불가능하다. 따라서 본 논문에서는 잡음제거 성능을 더욱 더 개선시키기 위해 전진방향 구간에서는 인공지능 기술 중 하나인 다층퍼셉트론(Multi-Layer Perceptron; MLP)를 적용하고, 회전구간에서는 Kalman Filter를 적용하여 Kalman Filter만을 사용한 경우보다 우수한 잡음제거 기법을 제안한다. 시뮬레이션을 통해 제안한 방법이 Kalman Filter만을 사용한 경우보다 조타기의 오동작을 방지하여 선박의 전진방향 운동이 개선됨을 확인할 수 있다.

We developed a wet scrubber by applying cyclone flow to the gas flow and using a spiral filter structure. While the size of a new scrubber was about half that of a conventional scrubber, the device showed relatively high efficiency in pollutants removal such as particulate matter and compounds inducing odor. The new scrubber installed in a plating industry showed a higher removal efficiency of about 5% for dust, about 23% for hydrogen chloride, and about 23% for sulfur dioxide compared to the conventional scrubber. Plurality of tubes in the spiral filer housing are arranged to be vertically shifted from each other. Because the upward residual gas does not directly rise vertically, the residence time of gas between the filter plates is extended. Thus, the purification efficiency of the pollutants was enhanced in the new scrubber. In addition, the new scrubber developed in this study is more cost effective because the cost saving in manufacturing it compared with a conventional scrubber increases with increasing the size of equipment. It is expected that a scrubber with better dust collecting efficiency can be obtained by carrying out a study in connection with facilities capable of controlling acidity of washing water.

The damage detection method using the extended Kalman filter(EKF) technique has been continuously used since EKF can estimation the responses of the damaged building structure and the stiffness of the structure. However, in the use of EKF, the requirement of setting the initial paramters P, Q, and R has caused the divergence and instability of the state vector, and various researches have been conducted to determine theses parameters. In this paper, adaptive extended Kalman filter(AEKF) method is proposed to solve the problem of setting the values of P, Q, and R, which are important parameters determining the convergence performance of the EKF state vector. By using the AEKF method proposed in this study, the P, Q, and R parameters are updated every k steps. The proposed algorithm is applied for the estimation of stiffness and the damage detection of 3-DOF problem. Based of the verification, it can be found that the selection process for the values of P, Q, and R can improve the convergence performance of EKF.

본 연구는 냉동전처리 기술이 분리막 기반의 슬러지 탈수공정에 미치는 영향에 대해 연구하였다. 냉동법은 응집법이나 원심분리법과는 달리, 슬러지 Cell lysis를 통해 Cell의 체액을 유출시킬 수 있음을 확인하였다. Cell lysis 이후 슬러지를 정밀여과법으로 분리하여 슬러지 탈수효율을 증가시키고자 하였으나, 냉동전처리로 인해 슬러지의 모세관 흡입시간과 여과소요시간이 약 13배 증가함으로써 슬러지 탈수효율이 감소하였다. 이는 슬러지로부터 방출된 유기물에 의한 슬러지 케이크 형성과 작은 슬러지 입자에 의한 세공차단현상에 의한 것이다. 적절한 공극 크기 및 슬러지 흡착에 내성을 갖는 분리막의 개발이 이루어 진다면, 냉동전처리와 분리막 공정의 혼성화기술은 슬러지 탈수에 적용 가능할 수 있을 것으로 보인다.

In this paper, the long-term reliability of swash plate type hydraulic pump is studied by prognostics method. For the purpose, the pumping power of hydraulic pump is measured for 00 cycles and the performance after 00 cycles is estimated using the particle filter method. To verify the predicted 00 cycle's performance, the actual test results are compared with the estimated result and the trend of estimation is well matched with actual test results. The long-term reliability evaluation using the prognostics method performed in this study shows the feasibility that can be utilized in development phase of tracked vehicle to improve the quality of initial products.

Membrane distillation (MD) is a thermally driven desalination process with a hydrophobic membrane. MD process has been known to have a lower fouling potential compared to other pressure-based membrane desalination process (NF, RO). However, membrane fouling also occurs in MD process. In this study, the membrane fouling was observed in MD process according to the pre-treatment processes. The filtration and precipitation processes were applied as the pre-treatment to prevent the membrane fouling. The pore sizes of roughing filters were 0.4, 5, 10, 30, and 60 ㎛. The concentration of the coagulant was 1.2 mg/L as FeCl3. The membrane fouling on MD membrane was successfully removed with both pre-treatment processes.

Currently, the cutting oil supply device is not equipped to cool the cutting oil. Therefore, additional cooling device should be connected to cool the cutting oil. This has the disadvantage of increasing the size of the device and reducing its cooling capability. To overcome these shortcomings, cooling coils are applied to the outside of the cutting oil filtering device to develop a heat exchanger filter for simultaneous coolant filtering and cooling to improve the compactness of the cutting oil supply device and cooling capability of the cutting oil. For the development of heat exchanger filter, flow and heat transfer analysis were performed. Due to the small heat transfer area of 10 cooling coils, less heat exchange occurred. In the 20 cooling coils, the coolant cooling coils prevented smooth flow of the cooling oil in the heat exchanger filter. The cooling efficiency of the 15 cooling coils were best, and the cooling temperature decreased non-linearly as the supply flow rate of the cutting oil increased.

As the demand for high-speed and high-precision machining increases, the need for cooling and filtering of cutting oil is high. A new concept of coolant heat exchange filter is developed by installing cooling coil through which refrigerant(R410-a) passes through the coolant filtering device. For structural safety evaluation of the heat exchanger filter for cutting oil suppling device of machine tool, thermal stress and vibration analysis were performed using ANSYS program. The results of structural and thermal stress analyses have led to the conclusion that the cooling system has structural stability. From modal analysis, first natural frequency is 12.37 hz and deformation is 22.041 mm. Sixth natural frequency is 26.887 hz and deformation is 25.563 mm.