• 제목/요약/키워드: Power lack ratio

검색결과 39건 처리시간 0.028초

트랙터 부착형 양파수확기의 작업 속도에 따른 견인 부하와 구조 안정성에 관한 실험적 연구 (Experimental Study on the Drawbar Pull and Structural Safety of an Onion Harvester Attached to a Tractor)

  • 신창섭;김준희;하유신;박두산
    • 한국기계가공학회지
    • /
    • 제18권4호
    • /
    • pp.16-25
    • /
    • 2019
  • Recently, due to labor shortages in rural areas within South Korea, the demand for upland-field machinery is growing. In addition, there is a lack of development of systematic performance testing of upland-field machinery. Thus, this study examined structural safety and drawbar pull based on soil properties, as a first step for systematic performance testing on the test bed. First, the properties of soil samples from 10 spots within the experimental site were examined. Second, the strain was measured and converted into stress on 8 points of an onion harvester that are likely to fail. More specifically, the chosen parts are linked to the power, along with the drawbar pull, using a 6-component load cell equipped between the tractor and the onion harvester. The water content of the soil ranged between 5.7%-7.5%, and the strength between 250-1171 kPa. The test soil was subsequently classified into loam soil based on the size distribution ratio of the sieved soil. The onion harvester can be considered as structurally safe based on the derived safety factor and the drawbar pull of 115-1194 kgf, according to the working speed based on agricultural fieldwork.

Minimally Invasive Procedure versus Conventional Redo Sternotomy for Mitral Valve Surgery in Patients with Previous Cardiac Surgery: A Systematic Review and Meta-Analysis

  • Muhammad Ali Tariq;Minhail Khalid Malik;Qazi Shurjeel Uddin;Zahabia Altaf;Mariam Zafar
    • Journal of Chest Surgery
    • /
    • 제56권6호
    • /
    • pp.374-386
    • /
    • 2023
  • Background: The heightened morbidity and mortality associated with repeat cardiac surgery are well documented. Redo median sternotomy (MS) and minimally invasive valve surgery are options for patients with prior cardiac surgery who require mitral valve surgery (MVS). We conducted a systematic review and meta-analysis comparing the outcomes of redo MS and minimally invasive MVS (MIMVS) in this population. Methods: We searched PubMed, EMBASE, and Scopus for studies comparing outcomes of redo MS and MIMVS for MVS. To calculate risk ratios (RRs) for binary outcomes and weighted mean differences (MDs) for continuous data, we employed a random-effects model. Results: We included 12 retrospective observational studies, comprising 4157 participants (675 for MIMVS; 3482 for redo MS). Reductions in mortality (RR, 0.54; 95% confidence interval [CI], 0.37-0.80), length of hospital stay (MD, -4.23; 95% CI, -5.77 to -2.68), length of intensive care unit (ICU) stay (MD, -2.02; 95% CI, -3.17 to -0.88), and new-onset acute kidney injury (AKI) risk (odds ratio, 0.34; 95% CI, 0.19 to 0.61) were statistically significant and favored MIMVS (p<0.05). No significant differences were observed in aortic cross-clamp time, cardiopulmonary bypass time, or risk of perioperative stroke, new-onset atrial fibrillation, surgical site infection, or reoperation for bleeding (p>0.05). Conclusion: The current literature, which primarily consists of retrospective comparisons, underscores certain benefits of MIMVS over redo MS. These include decreased mortality, shorter hospital and ICU stays, and reduced AKI risk. Given the lack of high-quality evidence, prospective randomized control trials with adequate power are necessary to investigate long-term outcomes.

Ultrasonographic Indeterminate Lymph Nodes in Preoperative Thyroid Cancer Patients: Malignancy Risk and Ultrasonographic Findings Predictive of Malignancy

  • Roh-Eul Yoo;Ji-hoon Kim;Jeong Mo Bae;Inpyeong Hwang;Koung Mi Kang;Tae Jin Yun;Seung Hong Choi;Chul-Ho Sohn;Jung Hyo Rhim;Sun-Won Park
    • Korean Journal of Radiology
    • /
    • 제21권5호
    • /
    • pp.598-604
    • /
    • 2020
  • Objective: Proper management of lymph nodes (LNs) with ultrasonographic (US) indeterminate features in thyroid cancer patients remains elusive. We aimed to evaluate the malignancy risk and US findings predictive of malignancy for US indeterminate LNs in preoperative thyroid cancer patients through node-by-node correlation. Materials and Methods: A total of 348 LNs in 284 thyroid cancer patients, who underwent fine-needle aspiration or core-needle biopsy between December 2006 and June 2015, were included. We determined the malignancy risks for US probably benign, indeterminate, and suspicious categories. For US indeterminate LNs, which had neither echogenic hilum nor hilar vascularity in the absence of any suspicious finding, US findings were compared between benign and metastatic LNs using Mann-Whitney U test and Fisher's exact test. Results: US imaging diagnoses were probably benign in 20.7% (n = 72) cases, indeterminate in 23.6% (n = 82), and suspicious in 55.7% (n = 194). Malignancy risk of US indeterminate LNs (19.5% [16/82]) differed from those of the US probably benign (2.8% [2/72]) (p = 0.002) and US suspicious LNs (78.4% [152/194]) (p < 0.001). Among US indeterminate LNs, there were no significant differences in short, long, and long-to-short diameter (L/S) ratios between benign and metastatic LNs (3.9 vs. 3.8 mm, p = 0.619; 7.3 vs. 7.3 mm, p = 0.590; 1.9 vs. 1.9, p = 0.652). Conclusion: US indeterminate LNs were frequently encountered during preoperative evaluation and had intermediate malignancy risk. Given the lack of discriminative power of size criteria and L/S ratio, clinical factors such as surgical strategy and node size should be considered for proper triage of US indeterminate LNs in thyroid cancer.

콘크리트용 골재로서의 Bottom Ash 활용성 평가 (Evaluation of Bottom Ash on the Application for the Aggregate of Concrete)

  • 김상철
    • 한국건설순환자원학회논문집
    • /
    • 제5권2호
    • /
    • pp.105-115
    • /
    • 2010
  • 산업의 발전과 함께 산업폐기물의 증가와 그에 따른 처리할 회사장 부족, 유해한 성분 함유로 인한 환경상의 문제 등에 대한 해결 방안의 일환으로, 본 연구에서는 석탄 화력발전소에서 발생되는 석탄회 중에서 bottom ash를 대상으로 콘크리트용 골재로서의 유용성 여부를 평가하고자 하였다. 먼저 잔골재와 굵은 골재의 대체재로서의 적절성 평가를 위해 경도시험, 입도분포시험, 흡수량시험, S.E.M 분석시험 등의 물리적 시험을 수행하였고, 화학적 시험으로는 강열감량시험, X-ray를 통한 분석시험을 수행하였다. 콘크리트에 적용하였을 때 미치는 영향은 대체재로서의 비율을 달리하여 작업성 확보차원에서 슬럼프의 변화를 측정하였고, 굳은 콘크리트에서는 강도확보, 내투수성, 동결융해 저항성, 내황산성, 탄산화 저항성에 대해 평가하였다. 실험결과, 미립분의 부족과 일부 bottom ash에서 결속력 상의 문제가 존재하였으나 천연골재와 혼합하여 사용하고 배출시 공정 개선을 한다면 골재로써 충분히 사용성이 있는 것으로 평가되었다. 또한, 다공성을 갖고 있어 작업성 확보를 위해서는 단위수량이나 감수제의 증가가 요구되지만 일반강도 한도 내에서는 일정 비율로 천연골재와 혼합하여 사용하면 강도 확보에 문제가 없고 오히려 내구성 확보에 있어서는 유리한 것으로 나타났다.

  • PDF

심박변동 신호의 시-주파수 분석을 이용한 스트레스 분석에 관한 연구 (The Analysis of Mental Stress using Time-Frequency Analysis of Heart Rate Variability Signal)

  • 성홍모;이주성;김원식;이현숙;윤영로;신태민
    • 대한의용생체공학회:의공학회지
    • /
    • 제25권6호
    • /
    • pp.581-587
    • /
    • 2004
  • FFT 나 AR 방법에 기초해서 파워스펙트럼을 구하는 방법은 생체신호와 같이 시간에 따라 그 특성이 빠르게 변화하는 신호에는 적합하지 않다. 반면, 시-주파수 방법은 시간에 따라 특성이 변하는 신호를 분석하기에 유용한 장점을 지니고 있다. 본 논문에서는 시-주파수 분석방법을 이용하여 시-주파수 영역에서 심박변동신호를 분석하는 방법을 연구하였다. 여러 종류의 시-주파수 커널 함수들 중에서 심박변동 신호에 적합한 방법을 찾기 위해서 모의 HRV 신호를 이용하였다. HRV 모의신호를 이용하여 커널 함수들의 시간-주파수 분해 능력과 교차성분제거 능력에 대한 평가를 하였고 시-주파수 영역에서 심박변동신호의 주파수 성분들을 추출해 내는 방법들을 제시하였다. 17명의 피험자들을 대상으로 동전쌓기 실험을 3분씩 시행하여 심전도 실험을 측정한 다음 이를 심박변동 신호로 재구성하여 분석하였다. 실험결과 피험자들에게 가해진 정신적 스트레스는 교감신경을 활성화 시켜 LF/HF 증가의 원인이 되는 것으로 나타났다. 실험수행능력에 따라 두 그룹으로 나누어 관찰하였는데 스트레스를 많이 받는 그룹이 그렇지 않은 경우에 비해 작업능력이 떨어짐을 알 수 있었다.

딥러닝 시계열 알고리즘 적용한 기업부도예측모형 유용성 검증 (Corporate Default Prediction Model Using Deep Learning Time Series Algorithm, RNN and LSTM)

  • 차성재;강정석
    • 지능정보연구
    • /
    • 제24권4호
    • /
    • pp.1-32
    • /
    • 2018
  • 본 연구는 경제적으로 국내에 큰 영향을 주었던 글로벌 금융위기를 기반으로 총 10년의 연간 기업데이터를 이용한다. 먼저 시대 변화 흐름에 일관성있는 부도 모형을 구축하는 것을 목표로 금융위기 이전(2000~2006년)의 데이터를 학습한다. 이후 매개 변수 튜닝을 통해 금융위기 기간이 포함(2007~2008년)된 유효성 검증 데이터가 학습데이터의 결과와 비슷한 양상을 보이고, 우수한 예측력을 가지도록 조정한다. 이후 학습 및 유효성 검증 데이터를 통합(2000~2008년)하여 유효성 검증 때와 같은 매개변수를 적용하여 모형을 재구축하고, 결과적으로 최종 학습된 모형을 기반으로 시험 데이터(2009년) 결과를 바탕으로 딥러닝 시계열 알고리즘 기반의 기업부도예측 모형이 유용함을 검증한다. 부도에 대한 정의는 Lee(2015) 연구와 동일하게 기업의 상장폐지 사유들 중 실적이 부진했던 경우를 부도로 선정한다. 독립변수의 경우, 기존 선행연구에서 이용되었던 재무비율 변수를 비롯한 기타 재무정보를 포함한다. 이후 최적의 변수군을 선별하는 방식으로 다변량 판별분석, 로짓 모형, 그리고 Lasso 회귀분석 모형을 이용한다. 기업부도예측 모형 방법론으로는 Altman(1968)이 제시했던 다중판별분석 모형, Ohlson(1980)이 제시한 로짓모형, 그리고 비시계열 기계학습 기반 부도예측모형과 딥러닝 시계열 알고리즘을 이용한다. 기업 데이터의 경우, '비선형적인 변수들', 변수들의 '다중 공선성 문제', 그리고 '데이터 수 부족'이란 한계점이 존재한다. 이에 로짓 모형은 '비선형성'을, Lasso 회귀분석 모형은 '다중 공선성 문제'를 해결하고, 가변적인 데이터 생성 방식을 이용하는 딥러닝 시계열 알고리즘을 접목함으로서 데이터 수가 부족한 점을 보완하여 연구를 진행한다. 현 정부를 비롯한 해외 정부에서는 4차 산업혁명을 통해 국가 및 사회의 시스템, 일상생활 전반을 아우르기 위해 힘쓰고 있다. 즉, 현재는 다양한 산업에 이르러 빅데이터를 이용한 딥러닝 연구가 활발히 진행되고 있지만, 금융 산업을 위한 연구분야는 아직도 미비하다. 따라서 이 연구는 기업 부도에 관하여 딥러닝 시계열 알고리즘 분석을 진행한 초기 논문으로서, 금융 데이터와 딥러닝 시계열 알고리즘을 접목한 연구를 시작하는 비 전공자에게 비교분석 자료로 쓰이기를 바란다.

병원 간호행정 개선을 위한 연구 (A Study for Improvement of Nursing Service Administration)

  • 박정호
    • 대한간호학회지
    • /
    • 제3권1호
    • /
    • pp.13-40
    • /
    • 1972
  • Much has teed changed in the field of hospital administration in the It wake of the rapid development of sciences, techniques ana systematic hospital management. However, we still have a long way to go in organization, in the quality of hospital employees and hospital equipment and facilities, and in financial support in order to achieve proper hospital management. The above factors greatly effect the ability of hospitals to fulfill their obligation in patient care and nursing services. The purpose of this study is to determine the optimal methods of standardization and quality nursing so as to improve present nursing services through investigations and analyses of various problems concerning nursing administration. This study has been undertaken during the six month period from October 1971 to March 1972. The 41 comprehensive hospitals have been selected iron amongst the 139 in the whole country. These have been categorized according-to the specific purposes of their establishment, such as 7 university hospitals, 18 national or public hospitals, 12 religious hospitals and 4 enterprise ones. The following conclusions have been acquired thus far from information obtained through interviews with nursing directors who are in charge of the nursing administration in each hospital, and further investigations concerning the purposes of establishment, the organization, personnel arrangements, working conditions, practices of service, and budgets of the nursing service department. 1. The nursing administration along with its activities in this country has been uncritical1y adopted from that of the developed countries. It is necessary for us to re-establish a new medical and nursing system which is adequate for our social environments through continuous study and research. 2. The survey shows that the 7 university hospitals were chiefly concerned with education, medical care and research; the 18 national or public hospitals with medical care, public health and charity work; the 2 religious hospitals with medical care, charity and missionary works; and the 4 enterprise hospitals with public health, medical care and charity works. In general, the main purposes of the hospitals were those of charity organizations in the pursuit of medical care, education and public benefits. 3. The survey shows that in general hospital facilities rate 64 per cent and medical care 60 per-cent against a 100 per cent optimum basis in accordance with the medical treatment law and approved criteria for training hospitals. In these respects, university hospitals have achieved the highest standards, followed by religious ones, enterprise ones, and national or public ones in that order. 4. The ages of nursing directors range from 30 to 50. The level of education achieved by most of the directors is that of graduation from a nursing technical high school and a three year nursing junior college; a very few have graduated from college or have taken graduate courses. 5. As for the career tenure of nurses in the hospitals: one-third of the nurses, or 38 per cent, have worked less than one year; those in the category of one year to two represent 24 pet cent. This means that a total of 62 per cent of the career nurses have been practicing their profession for less than two years. Career nurses with over 5 years experience number only 16 per cent: therefore the efficiency of nursing services has been rated very low. 6. As for the standard of education of the nurses: 62 per cent of them have taken a three year course of nursing in junior colleges, and 22 per cent in nursing technical high schools. College graduate nurses come up to only 15 per cent; and those with graduate course only 0.4 per cent. This indicates that most of the nurses are front nursing technical high schools and three year nursing junior colleges. Accordingly, it is advisable that nursing services be divided according to their functions, such as professional, technical nurses and nurse's aides. 7. The survey also shows that the purpose of nursing service administration in the hospitals has been regulated in writing in 74 per cent of the hospitals and not regulated in writing in 26 per cent of the hospitals. The general purposes of nursing are as follows: patient care, assistance in medical care and education. The main purpose of these nursing services is to establish proper operational and personnel management which focus on in-service education. 8. The nursing service departments belong to the medical departments in almost 60 per cent of the hospitals. Even though the nursing service department is formally separated, about 24 per cent of the hospitals regard it as a functional unit in the medical department. Only 5 per cent of the hospitals keep the department as a separate one. To the contrary, approximately 12 per cent of the hospitals have not established a nursing service department at all but surbodinate it to the other department. In this respect, it is required that a new hospital organization be made to acknowledge the independent function of the nursing department. In 76 per cent of the hospitals they have advisory committees under the nursing department, such as a dormitory self·regulating committee, an in-service education committee and a nursing procedure and policy committee. 9. Personnel arrangement and working conditions of nurses 1) The ratio of nurses to patients is as follows: In university hospitals, 1 to 2.9 for hospitalized patients and 1 to 4.0 for out-patients; in religious hospitals, 1 to 2.3 for hospitalized patients and 1 to 5.4 for out-patients. Grouped together this indicates that one nurse covers 2.2 hospitalized patients and 4.3 out-patients on a daily basis. The current medical treatment law stipulates that one nurse should care for 2.5 hospitalized patients or 30.0 out-patients. Therefore the statistics indicate that nursing services are being peformed with an insufficient number of nurses to cover out-patients. The current law concerns the minimum number of nurses and disregards the required number of nurses for operation rooms, recovery rooms, delivery rooms, new-born baby rooms, central supply rooms and emergency rooms. Accordingly, tile medical treatment law has been requested to be amended. 2) The ratio of doctors to nurses: In university hospitals, the ratio is 1 to 1.1; in national of public hospitals, 1 to 0.8; in religious hospitals 1 to 0.5; and in private hospitals 1 to 0.7. The average ratio is 1 to 0.8; generally the ideal ratio is 3 to 1. Since the number of doctors working in hospitals has been recently increasing, the nursing services have consequently teen overloaded, sacrificing the services to the patients. 3) The ratio of nurses to clerical staff is 1 to 0.4. However, the ideal ratio is 5 to 1, that is, 1 to 0.2. This means that clerical personnel far outnumber the nursing staff. 4) The ratio of nurses to nurse's-aides; The average 2.5 to 1 indicates that most of the nursing service are delegated to nurse's-aides owing to the shortage of registered nurses. This is the main cause of the deterioration in the quality of nursing services. It is a real problem in the guest for better nursing services that certain hospitals employ a disproportionate number of nurse's-aides in order to meet financial requirements. 5) As for the working conditions, most of hospitals employ a three-shift day with 8 hours of duty each. However, certain hospitals still use two shifts a day. 6) As for the working environment, most of the hospitals lack welfare and hygienic facilities. 7) The salary basis is the highest in the private university hospitals, with enterprise hospitals next and religious hospitals and national or public ones lowest. 8) Method of employment is made through paper screening, and further that the appointment of nurses is conditional upon the favorable opinion of the nursing directors. 9) The unemployment ratio for one year in 1971 averaged 29 per cent. The reasons for unemployment indicate that the highest is because of marriage up to 40 per cent, and next is because of overseas employment. This high unemployment ratio further causes the deterioration of efficiency in nursing services and supplementary activities. The hospital authorities concerned should take this matter into a jeep consideration in order to reduce unemployment. 10) The importance of in-service education is well recognized and established. 1% has been noted that on the-job nurses. training has been most active, with nursing directors taking charge of the orientation programs of newly employed nurses. However, it is most necessary that a comprehensive study be made of instructors, contents and methods of education with a separate section for in-service education. 10. Nursing services'activities 1) Division of services and job descriptions are urgently required. 81 per rent of the hospitals keep written regulations of services in accordance with nursing service manuals. 19 per cent of the hospitals do not keep written regulations. Most of hospitals delegate to the nursing directors or certain supervisors the power of stipulating service regulations. In 21 per cent of the total hospitals they have policy committees, standardization committees and advisory committees to proceed with the stipulation of regulations. 2) Approximately 81 per cent of the hospitals have service channels in which directors, supervisors, head nurses and staff nurses perform their appropriate services according to the service plans and make up the service reports. In approximately 19 per cent of the hospitals the staff perform their nursing services without utilizing the above channels. 3) In the performance of nursing services, a ward manual is considered the most important one to be utilized in about 32 percent of hospitals. 25 per cent of hospitals indicate they use a kardex; 17 per cent use ward-rounding, and others take advantage of work sheets or coordination with other departments through conferences. 4) In about 78 per cent of hospitals they have records which indicate the status of personnel, and in 22 per cent they have not. 5) It has been advised that morale among nurses may be increased, ensuring more efficient services, by their being able to exchange opinions and views with each other. 6) The satisfactory performance of nursing services rely on the following factors to the degree indicated: approximately 32 per cent to the systematic nursing activities and services; 27 per cent to the head nurses ability for nursing diagnosis; 22 per cent to an effective supervisory system; 16 per cent to the hospital facilities and proper supply, and 3 per cent to effective in·service education. This means that nurses, supervisors, head nurses and directors play the most important roles in the performance of nursing services. 11. About 87 per cent of the hospitals do not have separate budgets for their nursing departments, and only 13 per cent of the hospitals have separate budgets. It is recommended that the planning and execution of the nursing administration be delegated to the pertinent administrators in order to bring about improved proved performances and activities in nursing services.

  • PDF

동질도 평가를 통한 실버세대 세분군 분류 및 평가 (Mature Market Sub-segmentation and Its Evaluation by the Degree of Homogeneity)

  • 배재호
    • 유통과학연구
    • /
    • 제8권3호
    • /
    • pp.27-35
    • /
    • 2010
  • 실버세대의 중요성은 인구 증가뿐만 아니라 구매력의 향상 및 의사 표현의 강도가 증가하면서 더욱 커지고 있다. 이에 따라 과거 실버세대 전체를 대상으로 접근하던 마케팅 전략은 실버세대의 특성에 따라 적절히 분류하여 접근하는 방식으로 수정되는 것이 적절하다. 또한 세분군 분류 결과에 따라 고객 접근 전략이 결정되므로, 세분군이 얼마나 동일한 특성을 보유하고 있는 지는 마케팅 계획 수립에 매우 중요한 요소가 된다. 따라서 이론적으로 동일 세분군에 속해 있는 고객의 니즈는 대체로 일치해야 한다. 본 연구에서는 실버세대의 생활 행태와 생애 단계를 감안하여, 실버 세대 대상의 마케팅을 위한 세분군 (細分群) 분류를 수행하였으며, 분류된 세분군의 니즈가 얼마나 일치하고 있는지를 측정하기 위하여 동질도 (DoH: Degrees of Homogeneity)를 측정하였다. 동질도는 각 세분군을 대상으로 수행된 설문조사의 객관식 문항 별로 최다 응답자가 선택한 보기 문항이 다른 문항에 비하여 유의미하게 많다고 판단되는 문항의 수를 전체 문항의 수로 나눈 것으로 정의하였다. 본 연구는 동질도를 활용한 세분군 분류 결과의 적절성 평가 방법을 제시하였다는데 의의가 있으며, 다양한 분야에서 응용될 수 있을 것으로 판단된다. 또한 본 연구에서 제시한 실버세대 세분군 분류 결과는 점차 증가하고 있는 실버세대를 위한 마케팅 방안 수립의 기본 자료로 활용될 수 있을 것으로 판단된다.

  • PDF

인터넷쇼핑몰의 VMD 구성요인에 대한 탐색적 연구 (An Exploratory Study on the Components of Visual Merchandising of Internet Shopping Mall)

  • 김광석;신종국;구동모
    • 마케팅과학연구
    • /
    • 제18권2호
    • /
    • pp.19-45
    • /
    • 2008
  • 본 연구는 인터넷쇼핑몰 비주얼 머천다이징의 주요차원을 고객이 쇼핑몰에 진입한 후 정보탐색과 대안평가를 거치는 등의 쇼핑과정을 토대로 AIDA모형 관점에서 점포, 제품, 촉진에 초점을 맞추었다. VMD의 주요차원(primary dimensions)으로는 점포디자인, 머천다이징, 그리고 머천다이징단서로 구분하였다. 선행연구 결과를 토대로 점포다자인의 하위차원으로는 차별성, 간결성, 위치확인성을, 머천다이즈의 하위차원으로는 제품구색, 명성, 정보성을, 그리고 머천다이징단서의 하위차원으로는 제품추천 및 링크를 설정하여 VMD태도와의 관계를 탐색적으로 조사하였다. 연구결과 이들 세 차원은 종속변수에 유의한 정의 영향을 미치는 것으로 나타났다.

  • PDF