에어컨 냉각 팬용 브러쉬레스 DC 전동기의 역기전력 분석에 대한 연구

조정현,김지현,정정원,황흥식,이치우 경성대학교 공학기술연구소 2012 공학기술연구지 Vol.18 No.-

Compared to conventional dc motors having the combination of commutators and brushes, a brushless DC (BLDC) motor is one of the highly efficient motors due to its electrical commutation without a brush, and this feature allows the BLDC otor to be more suitable for an application requiring no maintenance due to mechanical wear between a commutator and a brush. Also, the BLDC motor has a few benefits over both a dc motor and an induction motor such as high dynamic response, high efficiency, logn life span, and low noise in wide speed-torque region. This paper investigates the variation of voltage induced in phase windings in a BLDC motor in several cases with respect to stack length, steel grade, and coil material. This study is numerically conducted and it is verified from the theoritical point of view by comparing the result of simulation with that of experimental measurement.

복식자궁전적출술과 인공슬관절 치환술 환자에서 정맥내 자가통증조절이 수술 후 진통에 미치는 효과

최영균,남현옥,이정한,이근무,정순호,김영재,신치만 白中央醫療院 2005 仁濟醫學 Vol.26 No.1

Objective: Intravenous patient-controlled analgesia(IV PCA) is gaining wide spread popularity in the management of postoperative pain control. The purpose of this study is to evaluate the severity of pain after TAH and TKRA through comparing visual analogue scale(VAS) of pain of each patients who received identical IV PCA protocol, and to improve our IV PCA protocol. Methods: TAH group includes twenty female patients who were scheduled for TAH. TKRA group includes twenty female patients who were scheduled for TKRA. Each group received fentanyl 50㎍ about 30minutes before the end of surgery, followed by IV PCA with fentanyl 1500 ㎍, ketolorac 300mg, ondansteron 8mg, normal saline 56㎖(total 96ml, basal infusion rate 1㎖/hr, bolus dose 1㎖, lockout time 10 minutes). VAS scores were recorded at 1, 6, 12, 24, 48 hours postoperatively. Total bolus doses and patients' satisfaction were checked after the end of analgesia. Results: VAS scores of TKRA group were significantly higher than those of TAH group at 12, 24, 48 hours postoperatively. VAS scores of both group progressively decreased(P<0.05). Patients' satisfaction score showed no significant difference between two groups. Total bolus dose of TKRA group was significantly higher than that of TAH. Conclusion: The postoperative pain of TKRA was more severe than that of TAH. TKRA group needed more profound postoperative pain control than TAH group. We should consider the increase of early postoperative period analgesic doses to acquire optimal pain control of both group.

지방공급원이 어린 병아리에서 에너지와 단백질 비율에 미치는 영향

최인숙,김현숙,지규만 숙명여자대학교 건강·생활과학연구소 2001 生活科學硏究誌 Vol.16 No.-

This study was designed to investigate the effect of dietary fat sources on calorie/protein(C/7) ratio in young chicks. In experiment 1, various sources of fats such as com oil, soy oil, rapeseed oil, palm oil, tallow, fish oil and hydrogenated fish oil were added individually at a level of 11.14% to practical type diets primarily based on corn and soybean meal. Control diet contacted 3% of corn oil. Eight groups of White Leghorn male chicks were fed purified isocaloric diets in experiment 1. The second experiment was to compare the effects of different levels of C/P ratio of the diets on performances and absorption rates of energy, protein and fat in the chick. In experiment 2, three groups(group 1: control 2 and 3) received diets which provided a calorie: protein ratio of 146.0, 146.5 and 164.5, respectively. Control diet(C/P ratio=146.0) was the same as in experiment 1. Another diet was added with 11.14% corn oil(C/P ratio=146.5) and the other diets with 10% com oil(C/P ratio=164.5). The diets in experiment 1 and 2 were fed ad libitum for 26 days individually. Ducting the 26 days of the experiment period, samples of feed and excreta were collected for calculations of the protein retention, fat and energy absorption of the diets. Excreta were collected ducting the last part of the experiment over five days at each batteries. In experiment 1 and 2, feed intake, body weight gain and feed/gain ratio were not statistically different from controls. Body weight gain, fed efficiency was evaluated in young chicks fed diets in which added fat varied, C/P ratio different. Body weight gain and feed efficiency did not change significantly when fat was added isocalorically. There were no statistically significant differences between groups in metabolizable energy. In conclusion these results suggest that calorie/protein ratio is influenced by dietary fat sources in young chicks.

재생골재를 사용한 콘크리트의 특성에 관한 연구

박영신,지석원,이세현,서치호 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

The production of waste concrete is increased continuously by urban renewal and reconstruction, and the positive use of recycled concrete aggregates is needed. In this study, it is examined mechanical properties of recycled aggregates concrete used recycled fine and coarse aggregates for the technology development of the highly use of recycled aggregates. In the experiment. Recycled coarse aggregates is substitute for the rate of 0, 30, 60%, and recycled fine aggregates is substitute for natural aggregates the rate of 0, 25, 50, 75, 100% each. The result of the experiment is followed. 1. The slump and variation of slump as the time, is decreased irregularly according to the substitutive ratio of recycled aggregates, and the air content is increased. 2. The compressive and tensile strength is decreased according to the substitute ratio of recycled aggregates, but in the recycled aggregates 25%, the increase of strength is shown about 5% compared with normal concrete.

난소절제후 Estrogen을 투여한 흰쥐 대동맥에서 Protein Kinase C-α와 Fas 발현의 변화

이왕수,이상엽,안지현,송영빈,김학진,이광재,유재격,김상욱,김태호,김치정,류왕성 중앙대학교 의과대학 의과학연구소 2001 中央醫大誌 Vol.26 No.3

Estrogen is believed to decrease coronary artery disease. Protein kinase C-α(PKCα)appear to be important in signal conduction pathways. Estrogen treatment increases catalytic activity of PKCα,and activation of PKCαcan modulate estrogen receptor levels and responsiveness. And it was reported that activation of PKC can protect cells from apoptosis induced by Fas ligation. But the beneficial effect of estrogen on PKCαwas not clearly demonstrated. The objective of this study was to evaluate the role of PKCαafter ovariectomy and estrogen therapy in rat aorta. The results were summarized as below: 1. The significant pathological changes were not observed in the rat aorta irrelevant to ovariectomy and estrogen therapy. 2. The expression of Fas was decreased in the aorta of estrogen-treated rats than that of ovariectomized rats without estrogen therapy. 3. Increased expression of PKCαwas more marked in the aprta of estrogen-treated rats than that of ovariectomized rat without estrogen therapy. In conclusion,PKCαmay be important in signal conduation pathway on the effect of estrogen. Activation of PKCαby estrogen reduced Fas expression, suggesting that PKCαactivation may play a role in protection against atherasclerosis. Further studies are needed to elucidate the role of PKCαafter estrogen therapy.

급성 조증에서 기분안정제와 리스페리돈의 병합 투여 효과 : 다기관 개방연구

김광수,배치운,윤진상,김영훈,이양현,지익성,이철,송혜경,최성구,박원명 大韓神經精神醫學會 2005 신경정신의학 Vol.44 No.2

Ohjective : The primary purpose of this study was a replication of the effectiveness and tolerability of rispehdone in the treatment of patients with acute mania in very larger cohon in naturalistic treatment setting to extend the data on the effect and tolerability of risperidone in the treatment of patients with acute mania to Asian population. Methods : A total of 909 patients with DSM-TV criteria of bipolar disorder current manic and hypomanic episode, entered this large, open, multicentre study. The Young Mania Rating Scale (YMRS), Clinical Global Impression (CGI) and Simpson-Angus Rating Scale (SARS) were measured at baseline and weeks 1, 3 and 6, for the assessment of effectiveness and extra-pyramidal symptom (EPS). Results : This study showed statistically significant reduction of scores on the YMRS and CGI-s (mean change=-23.5±11.8, p<0.0001 ; mean change=-2.7±1.5, p<0.0001, respectively) from the baseline to the endpoint (week 6). Number of patients with 50% reduction or more in the YMRS and CGI-s scores was 693 (77.8%) and 630 (70.7%) at endpoint, respec-tively. There were no statistically significant increments of scores on SARS. Risperidone was generally well tolerated. Conclusion : The present larger open study demonstrates that hsperidone add-on therapy is effective and tolerable in treat-ment of bipolar disorder, replicating results in various controlled and uncontrolled studies from Western countries.

조선업의 작업환경측정결과를 이용한 노출평가의 문제점과 해결방향 : 유사노출군을 중심으로

노영만,임현우,김석일,박효만,정재열,박숙경,김현욱,정치경,이원철,김정만,김수근,고상백,Karl Siber,김은아,최정근 한국산업위생학회 2001 한국산업보건학회지 Vol.11 No.2

Statistical approaches for analysis of data from the limited number of samples in ship building industry(SBI) collected by an industrial hygienist for checking compliance to an occupational standard were considered. Sampling for com-pliance usually has been guided by judgment selection, rather than true randomness, resulting in the creation of compliance samples which approximate a censored sample from the upper tail of the exposure distribution. Similar exposure groups(SEGs) including welding and painting process were established to assess representative values in each groups after reviewing the whole production line in SBI. For the convenient statistical approaches, the code has assigned to each SEGs. The descriptive statistics and probability plotting were used to yield the representative values in each SEGs. In the first step, SEGs of 558 were established from 5 ship building companies, The 38 SEGs showed the uncertainty are divided into each 5 companies and assessed the repre-sentative values again. The 44 SEGs in each companies was not showed the normal and lognormal distribution was analyzed each data. And also, recommendation was suggested to resolve the uncertainty in each groups.

Shrinkage-based biased signal-to-noise ratio estimator using pilot and data symbols for linearly modulated signals

Chee-Hyun Park,Soojeong Lee,Joon-Hyuk Chang IET 2015 IET COMMUNICATIONS Vol.9 No.11

<P>In diverse engineering problems including wireless communications, the estimate of the signal-to-noise ratio (SNR) is required. In this study, the authors develop a shrinkage-based SNR estimator in the data-aided and non-data-aided schemes for higher <I>M</I>-ary phase-shift-keying (<I>M</I> ≥ 8) and quadrature amplitude modulations. The observed Cramér-Rao lower bound is used as the variance of the expectation maximisation estimator to determine the optimal shrinkage factor. Simulation results show that the normalised mean-squared error of the proposed method is lower than that of the expectation maximisation method for low and moderate SNR conditions.</P>

Control of Three-Phase Inverter for AC Motor Drive With Small DC-Link Capacitor Fed by Single-Phase AC Source

Hyun-Sam Jung,Seung-Jun Chee,Seung-Ki Sul,Young-Jae Park,Hyun-Soo Park,Woo-Kyu Kim IEEE 2014 IEEE transactions on industry applications Vol.50 No.2

<P>If a small dc-link capacitor is used in the dc link fed by a single-phase ac source, then the dc-link voltage severely fluctuates at twice of the source frequency. To handle this fluctuation, the concept of “average voltage constraint” is proposed in this study. On the basis of this concept, a flux-weakening scheme, generating the d-axis current reference (i<SUB>ds</SUB><SUP>r</SUP>*) for the interior permanent-magnet synchronous machine, is devised. The q-axis current reference (i<SUB>qs</SUB><SUP>r</SUP>*) is modified for the unity power factor operation in the viewpoint of an ac source without an additional sensor. The proposed scheme has been applied to the inverter-driven 1-kW compressor of an air conditioner. From the experimental results, it has been verified that the compressor operates well at the required operating condition, regardless of the severe fluctuation of dc-link voltage, because of the reduced dc-link capacitance. The frequency spectrum of the ac source current reveals that the harmonics of the source current meet the regulation of IEC 61000-3-2 Class A and that the overall power factor is above 96% without any additional circuit, such as an input filter and a power factor correction circuit.</P>

Molecular Vibration-Activity Relationship in the Agonism of Adenosine Receptors

Chee, Hyun Keun,Oh, S. June Korea Genome Organization 2013 Genomics & informatics Vol.11 No.4

The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands.