A PID control with Feedfoward Controller for Controlling Fluid Temperature in Heat Exchanger

열교환기는 고온의 유체와 저온의 유체가 전열 벽을 사이에 두고 고온에서 저온으로 열을 이동시키는 장치로 화학, 선박 등의 다양한 분야에서 사용되고 있다. 열교환기의 유체온도 제어의 경우 시간지연이 크거나 혹은 외란이 크게 작용할 경우 원하는 결과를 얻기 어렵다. 이 문제를 해결하기 위해 피드포워드(feedforward) 제어기를 PID 제어기에 결합시키는 방법을 생각할 수 있다. 본 논문에서는 열교환기의 온도제어를 위해 피드포워드 제어기를 결합한 PID 제어기를 설계한다. 피드포워드 제어기는 외란의 영향을 줄이기 위해 외란을 미리 측정하여 제어입력에 반영시킨다. 피드포워드 제어기와 PID 제어기의 파라미터는 최적화 기법의 하나인 RCGA로 동조한다. 이때 평가함수로 Integral Absolute Error를 사용한다. 전체 제어시스템의 목표값 추종 성능을 개선하기 위해 외란을 고정하고 목표값을 계단상으로 변경시키면서 PID 제어기의 파라미터들을 동조한다. 제안한 방법의 타당성을 확인하기 위해 기존의 동조법인 Z-N의 폐루프 동조법, IMC 동조법과 시뮬레이션을 통해 비교 검토한다. |A heat exchanger is a device that moves heat from a high temperature to a low temperature between the heat transfer wall, and is used in various fields such as chemicals and ships. In the fluid temperature control of a heat exchanger, it is difficult to obtain the desired result if the time delay is great or the disturbance is large. To solve this problem, a method of combining a feedforward controller with a PID controller can be thought. This paper proposed a method to control temperature of the heat exchanger by combining the feedforward controller with the PID controller. In order to reduce the influence of disturbances, a sensor measures the disturbance in advance and a feedforward controller reflects it in the control input. For the parameter tuning of the controller, RCGA, one of the optimization tools, was used. At this time, Integral Absolute Error was used as an evaluation function. The parameters of the PID controller were tuned while fixing the disturbance and changing the setpoint value stepwise to improve the setpoint tracking performance of the entire control system. In order to identify the validity of the proposed method, comparison and review were carried out through the closed loop tuning method of Z-N, IMC tuning method which are the existing tuning methods and the simulation.List of Tables ⅲ List of Figures ⅳ Abstract ⅵ 제 1 장 서 론 1 1.1 연구 배경 및 동향 1 1.2 연구 내용 및 구성 2 제 2 장 열교환기 3 2.1 열교환기의 개요 3 2.2 열교환기의 수학적 모델링 5 제 3 장 유전알고리즘 11 3.1 유전알고리즘의 특징과 구조 11 3.2 실수코딩 13 3.3 초기집단 생성 13 3.4 유전연산자 14 3.5 적합도 평가 16 3.6 적합도 스케일링 17 3.7 엘리트 전략 17 3.8 종료 조건 17 제 4 장 PID 제어기 18 4.1 PID 제어기의 구성과 특징 18 4.2 PID 제어기의 동조 20 제 5 장 피드포워드 제어기가 결합된 PID 제어기 30 5.1 피드포워드 제어기가 결합된 PID 제어기 31 5.2 피드포워드 제어기가 결합된 PID 제어기 동조 33 제 6 장 시뮬레이션 및 검토 36 6.1 PID 제어기의 목표값 추종 성능 36 6.2 PID 제어기의 외란제거 성능 38 6.3 피드포워드 제어기를 결합한 PID 제어기의 성능 40 6.4 피드포워드 제어기 유무에 따른 PID 제어기의 외란제거 성능 42 제 7 장 결 론 43 참고문헌 44 감사의 글 46Maste

The Prophylactic Impact of Low Molecular Weight Heparin on Occurrence of Venous Thromboembolism after Colorectal Cancer Resection

Purpose: In western society, prophylaxis for venous thromboembolism (VIE) is the standard treatment under colorectal surgery for colorectal cancer. However, the incidence of VIE after colorectal surgery and the effect of prophylactic methods are not well known in Korea. The aim of this study is to evaluate the incidence of VIE and assess the efficacy and safety of low molecular weight heparin (enoxaparin) after major colorectal surgery in Korean patients with compression stockings. Methods: From Jan. 2006 to Dec. 2008, 1,727 consecutive patients underwent major colorectal surgery. Thirty-six were excluded due to the therapeutic use of enoxaparin. A final number of 1,691 patients were included. Graduated compression stockings were used in all patients and 654 were perioperatively given enoxaparin. Only compression stocking group (group A) and compression stocking with enoxaparin group (group B) were compared in terms of VTE. The event of VIE within 6 months after surgery was counted by clinical symptoms, then imaging findings were used for confirmation. Results: Total VIE developed in 10 patients (0.6%). Three with deep vein thrombosis had pulmonary embolism. Two had only pulmonary embolism. The rates of VTE were not different between group A and B (0.8% vs. 0.3%, P=0.333). Also, postoperative major bleeding was not significantly different. However, postoperative transfusion was higher in group B (P<0.001). Conclusion: The incidence of VTE was very low after colorectal surgery in Korean patients with compression stockings. The additional use of enoxaparin for colorectal cancer patients with compression stockings seems to have little benefit for VIE prophylaxis. 수술 후에 발생되는 정맥 혈전색전증은 임상적으로 중요하면서도 예방 가능한 합병증으로 알려져 왔다. 서양에서는 일반 수술의 경우 하지 심부 정맥혈전증 발생률이 20%정도이며 대장절제술의 경우는 30% 정도로 알려져 있다.(1)반면, 동양인들을 대상으로 한 연구들에서 수술 후 임상적으로 진단된 하지 심부 정맥혈전증은 0.27%의 환자에서 발생하였고, 폐동맥 색전증은 0.8% 이내로 서양에 비해 낮게 보고되었다.(2-5) 특히, 대장암 수술이 다른 일반 개복 수술에 비해서 정맥 혈전색전증 발생이 많은 것으로 보고되고 있고, 폐동맥 색전증의 빈도 또한 높다고 알려져 있다.(6)아시아에서 대장암 수술 후에 임상적으로 진단된 하지 심부 정맥혈전증의 빈도는 4.7%, 그리고 폐동맥 색전증은 1.7∼3.8%로 보고되었으며,(7,8) 서양에서는 수술 후 하지 심부정맥혈전증이 3.1∼51.7%에 이른다는 보고가 있다.(9-11)아직까지 국내에서는 대장절제술후의 정맥 혈전색전증의 발생률에 대한 연구가 거의 없었으며, 저분자량 헤파린(low molecular weight heparin)을 대장절제술을 시행하는 모든 환자에서 투여하는 것에 대한 의견도 정립되지 않은 상태이다. 본 연구에서는 대장암으로 대장절제술을 시행한 환자들을 대상으로 수술 시 압박스타킹(graduated compression stocking)만 사용한 군과 압박스타킹과 저분자량 헤파린을 같이 사용한 군으로 나누어서 정맥 혈전색전증의 발생 빈도와 저분자량 헤파린의 효용성 및 출혈 위험에 대해서 비교해 보았다.Cheung HYS, 2008, ASIAN J SURG, V31, P63Beekman R, 2006, CAN J SURG, V49, P197Bauduer F, 2005, MOL GENET METAB, V86, P91, DOI 10.1016/j.ymgme.2005.04.002Almawi W, 2005, J THROMB THROMBOLYS, V19, P189, DOI 10.1007/s11239-005-1313-xCheuk BLY, 2004, BRIT J SURG, V91, P424, DOI 10.1002/bjs.4454Otten HMMB, 2004, ARCH INTERN MED, V164, P190Kim YH, 2003, J BONE JOINT SURG BR, V85B, P661, DOI 10.1302/0301-620X.85B5.14012ANDERSON FA, 2003, CIRCULATION, V107, P19WILLEJORGENSEN P, 2003, COCHRANE DB SYST REV, DOI DOI 10.1002/14651858.CD001217CHUNG CC, 2003, COLORECTAL DIS, V5, P528GREENE FL, 2002, AJCC CANC STAGING MALee FY, 2001, ANZ J SURG, V71, P637McLeod RS, 2001, ANN SURG, V233, P438Marshall NJ, 2000, AUST NZ J SURG, V70, P6392000, DIS COLON RECTUM, V43, P1037Ho YH, 1999, DIS COLON RECTUM, V42, P196Schwenk W, 1998, SURG ENDOSC-ULTRAS, V12, P7Yoo MC, 1997, INT ORTHOP, V21, P399HO YH, 1996, DEEP VENOUS THROMBOS, P38REES DC, 1995, LANCET, V346, P1133IDO K, 1995, SURG ENDOSC-ULTRAS, V9, P310GREM JL, 1994, J CLIN ONCOL, V12, P560KUM CK, 1993, ANN ACAD MED SINGAP, V22, P895HUBER O, 1992, ARCH SURG-CHICAGO, V127, P310KIM YH, 1988, J BONE JOINT SURG AM, V70A, P878TORNGREN S, 1982, DIS COLON RECTUM, V25, P563TSAKOK FH, 1974, ANN AC AD MED SINGAP, V3, P399HWANG WS, 1968, SINGAPORE MED J, V9, P276TINCKLER LF, 1964, BRIT MED J, V1, P502

Water-resistant PEDOT: PSS hole transport layers by incorporating a photo-crosslinking agent for high-performance perovskite and polymer solar cells

We demonstrated a water-resistant PEDOT:PSS HTL by incorporating a photo-crosslinking agent into a PEDOT:PSS film. A crosslinking system was successfully formed inside the PEDOT:PSS film by simple and fast photo-polymerization of PCDSA monomers. Combination of the crosslinking system and MeOH surface treatment simultaneously improved the device efficiency and stability of both perovskite and polymer solar cells. The crosslinking system inside PEDOT:PSS changed its intrinsic water-soluble characteristic into a water-resistant property, thus preventing water penetration into the PEDOT:PSS film. In addition, MeOH treatment improved the surface conductivity and reduced the surface roughness of the PEDOT:PSS film by removing surface residues of PDAs and insulating PSS parts.This work was supported by the National Research Foundation of Korea (Grant No. NRF-2015R1C1A1A02036599), the Technology Development Program to Solve Climate Changes of the National Research Foundation (NRF) funded by the Ministry of Science, ICT &amp;amp; Future Planning (NRF-2016M1A2A2940914) and Samsung Research Funding Center of Samsung Electronics under Project Number SRFC-MA1501-06. The portion of this research conducted at the University of Ulsan was supported by a National Research Foundation of Korea grant (2014R1A4A1071686)

Charge Selective Interfacial Transport Layer, And Organic Electronic Device Using The Same

본 발명은 높은 전하 전송 효율 및 선택성을 가지는 전하선택적 계면전송층 및 이를 이용한 유기전자장치에 관한 것으로서, 자세하게는 i) 무기 반도체 물질(inorganic semiconducting material)과 ii) 상기 무기 반도체 물질과의 접촉 계면에 자발분극(spontaneous dipolar polarization)을 통한 다이폴(dipole)을 유도할 수 있는 물질로 구성된 전하선택적 계면전송층을 이용하여 유기 발광다이오드(OLED), 유기 솔라셀 (organic solar cells), 유기 트랜지스터 (organic TFTs), 유기 메모리, 유기 센서 등 유기 반도체를 이용한 다양한 유기전자 소자에 적용하는 기술에 대한 것이다

Open versus laparoscopic surgery for mid or low rectal cancer after neoadjuvant chemoradiotherapy (COREAN trial): 10-year follow-up of an open-label, non-inferiority, randomised controlled trial

Background Laparoscopic surgery has been widely used for rectal cancer; however, its long-term outcomes remain controversial. This study aimed to assess the long-term oncological safety of laparoscopic surgery for rectal cancer using 10-year follow-up data of the Comparison of Open versus laparoscopic surgery for mid or low REctal cancer After Neoadjuvant chemoradiotherapy (COREAN) trial. Methods The COREAN trial is an open-label, non-inferiority, randomised controlled trial. Eligible participants were aged 18-80 years, had cT3N0-2M0 middle or low rectal cancer with lesions located within 9 cm of the anal verge, and had been treated with preoperative chemoradiotherapy. Patients were randomly assigned (1:1) to open or laparoscopic surgery with a computer-generated random allocation sequence with a random permuted block design. Neither patients nor clinicians were masked to treatment assignment. Open or laparoscopic total mesorectal excision was done 6-8 weeks after the administration of preoperative concurrent chemoradiotherapy (fluoropyrimidines alone, doublet therapy, or triplet therapy) at a dose of 50.5 Gy over 5.5 weeks. Postoperative adjuvant chemotherapy was administered for 4 months. The primary endpoint of 3-year disease-free survival was published previously. Here, we report 10-year overall survival, disease-free survival, and local recurrence. Analyses were done in the modified intention-to-treat population of all participants who were randomly assigned and provided follow-up data. This study is registered with ClinicalTrials.gov, NCT00470951. Findings Of the 340 patients enrolled in the COREAN trial between April 4, 2006, and Aug 26, 2009 (170 patients in each group), two patients in the laparoscopic surgery group moved abroad and were lost to follow-up, so were not included in this 10-year analysis. The median duration of follow-up was 143 months (IQR 122-156). No differences were observed in 10-year overall survival (74.1% [95% CI 66.8-80.0] in the open surgery group vs 76.8% [69.6-82.5] in the laparoscopic surgery group; p=0.44), 10-year disease-free survival (59.3% [51.1-66.5] vs 64.3% [56.0-71.5]; p=0.20), or 10-year local recurrence (8.9% [5.2-15.0] vs 3.4% [1.4-7.9]; p=0.050) between the open surgery and laparoscopic surgery groups at 10 years after surgery. The stratified hazard ratios, adjusted for ypT and ypN classification and tumour regression grade, for open surgery versus laparoscopic surgery were 0.94 (95% CI 0.63-1.43) for overall survival, 1.05 (0.74-1.49) for disease-free survival, and 2.22 (0.78-6.34) for local recurrence. Interpretation The 10-year follow-up of the COREAN trial confirms the long-term oncological safety of laparoscopic surgery in patients with rectal cancer treated with preoperative chemoradiotherapy. Similar to open surgery, laparoscopic surgery does not compromise long-term survival outcomes in rectal cancer when performed by well trained surgeons. Copyright (C) 2021 Elsevier Ltd. All rights reserved