전류 불평형 최소화를 위한 SLIM의 형상 최적화

金奎卓 國立 昌原大學校 産業技術硏究所 1994 産技硏論文集 Vol.8 No.-

This paper is proposed a method that optimizes slot shape for minimization of static end effect in linear induction motor. The shape design to efficiency optimization and unbalanced current minimization are accomplished by combining finite element method and sequential unconstrained minimization technique. As a result, unbalance current of each phase is minimized.

Clow-Pole형 PM스텝모터의 동특성

김덕현,김탁규,홍정표 國立 昌原大學校 産業技術硏究所 1997 産技硏論文集 Vol.11 No.-

In this paper, the static and dynamic characteristics of clow-poled PM step motor is analyzed by Finite Element Method. Step by step technique coupled with circuit and mechanical equation are performed. And moving line technique is applied to reduce the computing time when unit step response and dynamic characteristics are analyzed. Driving circuit for experiment is made and to conform the validity of this study and analysis results are compared with experimental ones.

분할자석형 편측식 리니어 동기 모터의 정특성 및 제동도체 효과

金奎卓 창원대학교 공작기계기술연구센터 1999 연구업적집 Vol.1 No.1

In this paper, the static and dynamic characteristics of the LSM with 4 divided permanent magnet to eliminate a space harmonics of magnetic field are compared with conventional type one. The 7th, 11th and 13th space harmonic components of thrust that act on thrust ripple, noise and mechanical vibration are reduced from 1.04 1.44 0.42[%] to 0.34, 0.7, 0.42[%] respectively. Decreasing normal force/thrust from 10.33 to 9.12, effect of normal force that deteriorates driving characteristics is diminished. Also, constructing damper conductor at the space by divided magnet, the reduction of hunting and induced starting are possible. The introduced type LSM is more effective than conventional type one with solid plate under magnet in antiracing and smooth starting. To conform the validity of this study, analysis values are compared with experimental values.

Idle air valve 용 PM 스텝 모터의 구동 특성

金奎卓 國立 昌原大學校 産業技術硏究所 1995 産技硏論文集 Vol.9 No.-

본 연구에서는 자동차의 MPI 엔진의 공기 유량 제어용으로 쓰이는 PM형 스텝 모터를 퍼미언스법에 의하여 설계치로부터 정특성, 동특성 및 스텝 응답 특성을 해석하였다. 또한, 마이크로 프로세성인 i8051AH와, L297, L298 IC를 이용한 구동 회로를 설계, 제작하였으며, 1-2상여자방식에 의하여 스텝 모터를 구동시켜 계산치와 실험치를 비교, 검토하였다. In this study, the characteristics of PM step motor for idle air valves is analyzed by pearmeance method. Driving circuit is composed of micro processor(i8051AH), L297 and L298. The calculated results were discussed and compared to experimental results of PM step motor driven by 1-2 phase exciting method.

磁氣浮上列車用 리니어 모터의 最適 設計에 관한 硏究

金奎卓 國立 昌原大學校 産業技術硏究所 1992 産技硏論文集 Vol.6 No.-

In this study, Linear motor for electromagnetic levitation transit is designed by the method of proportional increment of electric and magnetic loading. For optimizing design parameter, it is used sequential unconstrained minimization technique. Analysis of the various charateristics of the linear motor are achieved by finite element method and equivalent circuit. From the numerical result, it is shown that optimal design is achieved.

리니어모터 이송시스템의 진동저감을 위한 이송속도 최적화

최영휴,최응영,김규탁 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-

This paper presents feed rate optimizaton of a PMLSM driven feed-slide for mininum vibrations by smoothing velocity curve with finite jerk. First of all, the PMLSM was designed and made to reduce detent force. Next, a PMLSM driven feed-slide system was mathematically modeled as a 4-degree-of-freedom lumped parameter model. The key idea of our vibration minimization method is to find out the most appropriate smooth velocity curve with finite jerk. The validity of our proposed method has been verified by comparing computer simulation results of the feed-slide model with experimental ones.

Propylene carbonate-derived size modulation of water cluster in pore-filled Nafion/polypropylene composite membrane for the use in vanadium redox flow batteries

Kim, Hyun Gyu,Kim, Riyul,Kim, Soohyun,Choi, Chanyong,Kim, Bugi,Guim, Hwanuk,Kim, Hee-Tak Elsevier 2018 Journal of industrial and engineering chemistry Vol.60 No.-

<P><B>Abstract</B></P> <P>There is an increasing need to develop an alternative to Nafion membrane in order to reduce the cost of vanadium redox flow batteries. Pore-filled composite membranes based on Nafion is one way to reduce the amount of costly material, however its chronic problem is low conductivity and water uptake ability. We suggest a novel approach to enhance the conductivity and water uptake by incorporating propylene carbonate to modulate water channel morphologies in Nafion directly. We present a pore-filled type Nafion composite membrane to prove the effect of PC addition. Small-angle X-ray scattering and simulation results are suggested for further understanding.</P>

Utilization of End-of-Life Care Rooms by Patients Who Died in a Single Hospice Unit at a National University Hospital in South Korea

Gyu Lee Kim,Seung Hun Lee,Yun Jin Kim,Jeong Gyu Lee,Yu Hyeon Yi,Young Jin Tak,Young Jin Ra,Sang Yeoup Lee,Young Hye Cho,Eun Ju Park,Young In Lee,Jung In Choi,Sae Rom Lee,Ryuk Jun Kwon,Soo Min Son Korean Society for Hospice and Palliative Care 2023 한국호스피스.완화의료학회지 Vol.26 No.2

Purpose: For the dignity of patients nearing the end of their lives, it is essential to provide end-of-life (EoL) care in a separate, dedicated space. This study investigated the utilization of specialized rooms for dying patients within a hospice unit. Methods: This retrospective study examined patients who died in a single hospice unit between January 1, 2017, and December 31, 2021. Utilizing medical records, we analyzed the circumstances surrounding death, the employment of specialized rooms for terminally ill patients, and the characteristics of those who received EoL care in a shared room. Results: During the 1,825-day survey period, deaths occurred on 632 days, and 799 patients died. Of these patients, 496 (62.1%) received EoL care in a dedicated room. The average duration of using this dedicated space was 1.08 days. Meanwhile, 188 patients (23.5%) died in a shared room. Logistic regression analysis revealed that a longer stay in the hospice unit was associated with a lower risk of receiving EoL care in a shared room (odds ratio [OR]=0.98, 95% confidence interval [CI] 0.97~0.99; P=0.002). Furthermore, a higher number of deaths on the day a patient died was associated with a greater risk of receiving EoL care in a shared room (OR=1.66, 95% CI 1.33~2.08; P<0.001). Conclusion: To ensure that more patients receive EoL care for an adequate duration in a private setting, additional research is necessary to increase the number of dedicated rooms and incorporate them into the hospice unit at an early stage.

A multicenter study of entecavir <i>vs.</i> tenofovir on prognosis of treatment-naïve chronic hepatitis B in South Korea

Kim, Seung Up,Seo, Yeon Seok,Lee, Han Ah,Kim, Mi Na,Lee, Yu Rim,Lee, Hye Won,Park, Jun Yong,Kim, Do Young,Ahn, Sang Hoon,Han, Kwang-Hyub,Hwang, Seong Gyu,Rim, Kyu Sung,Um, Soon Ho,Tak, Won Young,Kweon Elsevier 2019 Journal of hepatology Vol.71 No.3

<P><B>Background & Aims</B></P> <P>It is currently unclear which antiviral agent, entecavir (ETV) or tenofovir disoproxil fumarate (TDF), is superior for improving prognosis in patients with chronic hepatitis B (CHB). Here, we assessed the ability of these 2 antivirals to prevent liver-disease progression in treatment-naïve patients with CHB.</P> <P><B>Methods</B></P> <P>From 2012 to 2014, treatment-naïve patients with CHB who received ETV or TDF as a first-line antiviral agent were recruited from 4 academic teaching hospitals. Patients with decompensated cirrhosis or hepatocellular carcinoma (HCC) at enrollment were excluded. Cumulative probabilities of HCC and death or orthotopic liver transplant (OLT) were assessed.</P> <P><B>Results</B></P> <P>In total, 2,897 patients (1,484 and 1,413 in the ETV and TDF groups, respectively) were recruited. The annual HCC incidence was not statistically different between the ETV and TDF groups (1.92 <I>vs</I>. 1.69 per 100 person-years [PY], respectively; adjusted hazard ratio [HR] 0.975 [<I>p</I> = 0.852] by multivariate analysis). Propensity score (PS)-matched and inverse probability of treatment weighting (ITPW) analyses yielded similar patterns of results (HR 1.021 [<I>p</I> = 0.884] and 0.998 [<I>p</I> = 0.988], respectively). The annual incidence of death or OLT was not statistically different between the ETV and TDF groups (0.52 <I>vs</I>. 0.53 per 100 PY, respectively; adjusted HR 1.202 [<I>p</I> = 0.451]). PS-matched and ITPW analyses yielded similar patterns of results (HR 1.248 [<I>p</I> = 0.385] and 1.239 [<I>p</I> = 0.360], respectively). These findings were consistently reproduced in patients with compensated cirrhosis (all <I>p</I> >0.05).</P> <P><B>Conclusions</B></P> <P>The overall prognosis in terms of HCC and death or OLT was not statistically different between the ETV and TDF groups. Further studies are needed to validate our results.</P> <P><B>Lay summary</B></P> <P>It is currently unclear which antiviral agent, entecavir or tenofovir disoproxil fumarate, is superior for improving prognosis in patients with chronic hepatitis B virus infection. In this analysis we found that there was no difference in terms of overall prognosis, including risk of hepatocellular carcinoma, death, or the need for a liver transplant, in patients receiving either antiviral.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The hepatocellular carcinoma risk was not statistically different between the ETV and TDF groups. </LI> <LI> The death or liver transplant risk was not statistically different between the 2 groups. </LI> <LI> These results were consistently reproduced after adjusting for confounding variables. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

The Iron loss Estimation of IPMSM According to Current Phase Angle

Gyu-Won Cho,Dong-Yeong Kim,Gyu-Tak Kim 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.6

Variable iron loss as function of current phase angle of Interior Permanent Magnet Synchronous Motor(IPMSM) was calculated through Curve Fitting Method(CFM). Also, a magnetic flux density distribution of iron core according to current phase angle was analyzed, and an iron loss calculation was performed including harmonic distortion. The experiment was performed by production of non-magnetizing model for the separation of mechanical loss, and the iron loss was calculated by the measurement of input using power analyzer and output power using dynamometer. Some error was generated between experimental results and calculation value, but an iron loss diminution according to current phase angle followed a same pattern. So, errors were generated by measurement, vibration, noise, harmonic distortion loss, etc.