• 제목/요약/키워드: Fitting status

검색결과 58건 처리시간 0.032초

계류중인 선박의 프로펠러 추력 추정에 관한 연구 (A Study on the Propeller Thrust for a Moored Ship)

  • 하문근;송인행;김도정;위기섭;김성환
    • 대한조선학회논문집
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    • 제34권1호
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    • pp.50-59
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    • 1997
  • 선박의 시운전 수행 이전에 엔진 및 프로펠러의 작동상태를 체크하기 위하여 때때로 안벽계류 중에서 주기 및 발전기의 성능시험을 수행하는 데, 이때 주기관을 100% 작동시키는 것은 계류용 로프 및 안벽 비트의 강도 문제등의 여러가지 위험 부담을 갖게 된다. 본 연구는 이러한 시험에 대한 안전성 검토를 위해 필요한 프로펠러의 추력의 추정을 목적으로 하고 있다. 대상선은 최근에 건조한 대형 컨테이너선이며, 실선시험은 안벽계류 상태에서 수행되었기 때문에 프로펠러는 수면위로 노출되어 있는 상태에서 작동되었다. 이러한 낮은 프로펠러 축 몰수 수심에서 작동하는 안벽계류 상태에서의 프로펠러의 특성을 조사하기 위해 모형시험을 수행하였으며, 이들 시험결과로부터 안벽계류 시험중의 프로펠러의 추력에 관한 약산식이 도출되었다. 그 결과 프로펠러의 특성은 축 수심에 따라 크게 달라지는 것을 알 수 있으며, 특히 축 수심이 작아 프로펠러가 수면위에 노출되어 있는 경우에는, 같은 축 수성에서도 프로펠러 회전수에 지배되는 특성이 파악되었다. 한편 심수 중에서 작동하는 프로펠러에 대해서도 추력에 대한 추정식을 도출하여 실선 시험 담당자가 사용하기 쉽게 하였으며, bollard pull에서의 FPSO(Floating Production Storage and Offloading tanker based system) 의 프로펠러의 추력 계측값과 비교 검토 하였다.

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Determination of Critical Nitrogen Concentration and Dilution Curve for Rice Growth

  • Lee, Byun-Woo;Cui, Ri-Xian;Kim, Min-Ho;Kim, Jun-Hwan;Nam, Hong-Shik
    • 한국작물학회지
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    • 제47권2호
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    • pp.127-131
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    • 2002
  • Critical nitrogen concentration (Nc), which is defined as the minimum % N in shoots required to maintain the maximum growth rate of top dry weight (W) at any time, was determined for rice plant. Using two rice varietal groups, japonica varieties and an indica $\times$ japonica "Dasanbyeo", 18 data points fulfilling the statistical criteria for determining Nc were obtained through eight N-fertilization experiments over two years at Suwon (37$^{\circ}$16'N), Korea. Nc dilution curve for each variety was obtained by fitting the Nc-W relationship to power function. However, The critical nitrogen curves for the two variety groups were not different statistically. Thus, a Nc dilution curve was fitted for the Nc data points pooled over the two variety groups and proposed in rice as: Nc=4.08, where W<1.73 t h $a^{-1}$ , Nc=5.197 $W^{0.425}$3/ ($R^2$=0.964), where 1.73 t h $a^{-1}$ <W<12 t h $a^{-l}$. The Nc for W<1.73 t h $a^{-l}$ were estimated as a constant value of 4.08%, the mean value of the maximum N concentration for N-limiting condition and the minimum N concentration for N non-limiting condition. The model for Nc is applicable to diagnosing the nitrogen nutrition status during the rice growth period from emergence to heading stage. The Nc curve well discriminated the 144 data points between the N limiting and the N non-limiting groups regardless of varieties, cultural methods, and years.-limiting groups regardless of varieties, cultural methods, and years.

Numerical Model for Cerebrovascular Hemodynamics with Indocyanine Green Fluorescence Videoangiography

  • Hwayeong Cheon;Young-Je Son;Sung Bae Park;Pyoung-Seop Shim;Joo-Hiuk Son;Hee-Jin Yang
    • Journal of Korean Neurosurgical Society
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    • 제66권4호
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    • pp.382-392
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    • 2023
  • Objective : The use of indocyanine green videoangiography (ICG-VA) to assess blood flow in the brain during cerebrovascular surgery has been increasing. Clinical studies on ICG-VA have predominantly focused on qualitative analysis. However, quantitative analysis numerical modelling for time profiling enables a more accurate evaluation of blood flow kinetics. In this study, we established a multiple exponential modified Gaussian (multi-EMG) model for quantitative ICG-VA to understand accurately the status of cerebral hemodynamics. Methods : We obtained clinical data of cerebral blood flow acquired the quantitative analysis ICG-VA during cerebrovascular surgery. Varied asymmetric peak functions were compared to find the most matching function form with clinical data by using a nonlinear regression algorithm. To verify the result of the nonlinear regression, the mode function was applied to various types of data. Results : The proposed multi-EMG model is well fitted to the clinical data. Because the primary parameters-growth and decay rates, and peak center and heights-of the model are characteristics of model function, they provide accurate reference values for assessing cerebral hemodynamics in various conditions. In addition, the primary parameters can be estimated on the curves with partially missed data. The accuracy of the model estimation was verified by a repeated curve fitting method using manipulation of missing data. Conclusion : The multi-EMG model can possibly serve as a universal model for cerebral hemodynamics in a comparison with other asymmetric peak functions. According to the results, the model can be helpful for clinical research assessment of cerebrovascular hemodynamics in a clinical setting.

의복 종류별 수선 실태조사와 수선방법에 관한 분석 (A Study on the Actual Condition of Repair by Clothing Types and an Analysis of Repair Methods)

  • 김연희;박미경;송정아
    • 한국의류산업학회지
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    • 제25권3호
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    • pp.324-332
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    • 2023
  • Consumers are addressing the issue of dimensional dissatisfaction by repairing clothes, experimenting with style changes, and looking for cost-effective solutions that result in better-fitting garments. This study investigated the repair status by type of clothing, analyzed the method and frequency of repair by type of clothing category and season, and analyzed consumer redesign activities. The findings revealed that upper garments, such as T-shirts, jumpers, jackets, dress shirts, and dresses, were frequently repaired. The common modifications to upper garments included(in order of frequency) shortening sleeve length, shortening overall length, reducing garment width, zipper repair, and adjusting sleeve width. Lower garments, such as pants, jeans, skirts, and training pants, followed in terms of repair frequency. The modifications to lower garments included(in order of frequency) shortening length, reducing width, adjusting waist width (both narrowing and widening), replacing elastic bands, zipper repair, and lengthening. Repairs were more frequently conducted in the order of autumn, winter, spring, and summer. Repair methods varied depending on the clothing type and alterations involved to the length and width of garments and the replacement or removal of old sections. Redesigning clothing as a recycling method was found to enhance the cost-effectiveness of the collection. The study further confirmed the sustainability aspect of redesigning and reusing clothing.

다양한 다분류 SVM을 적용한 기업채권평가 (Corporate Bond Rating Using Various Multiclass Support Vector Machines)

  • 안현철;김경재
    • Asia pacific journal of information systems
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    • 제19권2호
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    • pp.157-178
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    • 2009
  • Corporate credit rating is a very important factor in the market for corporate debt. Information concerning corporate operations is often disseminated to market participants through the changes in credit ratings that are published by professional rating agencies, such as Standard and Poor's (S&P) and Moody's Investor Service. Since these agencies generally require a large fee for the service, and the periodically provided ratings sometimes do not reflect the default risk of the company at the time, it may be advantageous for bond-market participants to be able to classify credit ratings before the agencies actually publish them. As a result, it is very important for companies (especially, financial companies) to develop a proper model of credit rating. From a technical perspective, the credit rating constitutes a typical, multiclass, classification problem because rating agencies generally have ten or more categories of ratings. For example, S&P's ratings range from AAA for the highest-quality bonds to D for the lowest-quality bonds. The professional rating agencies emphasize the importance of analysts' subjective judgments in the determination of credit ratings. However, in practice, a mathematical model that uses the financial variables of companies plays an important role in determining credit ratings, since it is convenient to apply and cost efficient. These financial variables include the ratios that represent a company's leverage status, liquidity status, and profitability status. Several statistical and artificial intelligence (AI) techniques have been applied as tools for predicting credit ratings. Among them, artificial neural networks are most prevalent in the area of finance because of their broad applicability to many business problems and their preeminent ability to adapt. However, artificial neural networks also have many defects, including the difficulty in determining the values of the control parameters and the number of processing elements in the layer as well as the risk of over-fitting. Of late, because of their robustness and high accuracy, support vector machines (SVMs) have become popular as a solution for problems with generating accurate prediction. An SVM's solution may be globally optimal because SVMs seek to minimize structural risk. On the other hand, artificial neural network models may tend to find locally optimal solutions because they seek to minimize empirical risk. In addition, no parameters need to be tuned in SVMs, barring the upper bound for non-separable cases in linear SVMs. Since SVMs were originally devised for binary classification, however they are not intrinsically geared for multiclass classifications as in credit ratings. Thus, researchers have tried to extend the original SVM to multiclass classification. Hitherto, a variety of techniques to extend standard SVMs to multiclass SVMs (MSVMs) has been proposed in the literature Only a few types of MSVM are, however, tested using prior studies that apply MSVMs to credit ratings studies. In this study, we examined six different techniques of MSVMs: (1) One-Against-One, (2) One-Against-AIL (3) DAGSVM, (4) ECOC, (5) Method of Weston and Watkins, and (6) Method of Crammer and Singer. In addition, we examined the prediction accuracy of some modified version of conventional MSVM techniques. To find the most appropriate technique of MSVMs for corporate bond rating, we applied all the techniques of MSVMs to a real-world case of credit rating in Korea. The best application is in corporate bond rating, which is the most frequently studied area of credit rating for specific debt issues or other financial obligations. For our study the research data were collected from National Information and Credit Evaluation, Inc., a major bond-rating company in Korea. The data set is comprised of the bond-ratings for the year 2002 and various financial variables for 1,295 companies from the manufacturing industry in Korea. We compared the results of these techniques with one another, and with those of traditional methods for credit ratings, such as multiple discriminant analysis (MDA), multinomial logistic regression (MLOGIT), and artificial neural networks (ANNs). As a result, we found that DAGSVM with an ordered list was the best approach for the prediction of bond rating. In addition, we found that the modified version of ECOC approach can yield higher prediction accuracy for the cases showing clear patterns.

Use of Unmanned Aerial Vehicle for Multi-temporal Monitoring of Soybean Vegetation Fraction

  • Yun, Hee Sup;Park, Soo Hyun;Kim, Hak-Jin;Lee, Wonsuk Daniel;Lee, Kyung Do;Hong, Suk Young;Jung, Gun Ho
    • Journal of Biosystems Engineering
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    • 제41권2호
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    • pp.126-137
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    • 2016
  • Purpose: The overall objective of this study was to evaluate the vegetation fraction of soybeans, grown under different cropping conditions using an unmanned aerial vehicle (UAV) equipped with a red, green, and blue (RGB) camera. Methods: Test plots were prepared based on different cropping treatments, i.e., soybean single-cropping, with and without herbicide application and soybean and barley-cover cropping, with and without herbicide application. The UAV flights were manually controlled using a remote flight controller on the ground, with 2.4 GHz radio frequency communication. For image pre-processing, the acquired images were pre-treated and georeferenced using a fisheye distortion removal function, and ground control points were collected using Google Maps. Tarpaulin panels of different colors were used to calibrate the multi-temporal images by converting the RGB digital number values into the RGB reflectance spectrum, utilizing a linear regression method. Excess Green (ExG) vegetation indices for each of the test plots were compared with the M-statistic method in order to quantitatively evaluate the greenness of soybean fields under different cropping systems. Results: The reflectance calibration methods used in the study showed high coefficients of determination, ranging from 0.8 to 0.9, indicating the feasibility of a linear regression fitting method for monitoring multi-temporal RGB images of soybean fields. As expected, the ExG vegetation indices changed according to different soybean growth stages, showing clear differences among the test plots with different cropping treatments in the early season of < 60 days after sowing (DAS). With the M-statistic method, the test plots under different treatments could be discriminated in the early seasons of <41 DAS, showing a value of M > 1. Conclusion: Therefore, multi-temporal images obtained with an UAV and a RGB camera could be applied for quantifying overall vegetation fractions and crop growth status, and this information could contribute to determine proper treatments for the vegetation fraction.

Spatial and Temporal Analyses of Cervical Cancer Patients in Upper Northern Thailand

  • Thongsak, Natthapat;Chitapanarux, Imjai;Suprasert, Prapaporn;Prasitwattanaseree, Sukon;Bunyatisai, Walaithip;Sripan, Patumrat;Traisathit, Patrinee
    • Asian Pacific Journal of Cancer Prevention
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    • 제17권11호
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    • pp.5011-5017
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    • 2016
  • Background: Cervical cancer is a major public health problem worldwide. There have been several studies indicating that risk is associated with geographic location and that the incidence of cervical cancer has changed over time. In Thailand, incidence rates have also been found to be different in each region. Methods: Participants were women living or having lived in upper Northern Thailand and subjected to cervical screening at Maharaj Nakorn Chiang Mai Hospital between January 2010 and December 2014. Generalized additive models with Loess smooth curve fitting were applied to estimate the risk of cervical cancer. For the spatial analysis, Google Maps were employed to find the geographical locations of the participants' addresses. The Quantum Geographic Information System was used to make a map of cervical cancer risk. Two univariate smooths: x equal to the residency duration was used in the temporal analysis of residency duration, and x equal to the calendar year that participants moved to upper Northern Thailand or birth year for participants already living there, were used in the temporal analysis of the earliest year. The spatial-temporal analysis was conducted in the same way as the spatial analysis except that the data were split into overlapping calendar years. Results: In the spatial analysis, the risk of cervical cancer was shown to be highest in the Eastern sector of upper Northern Thailand (p-value <0.001). In the temporal analysis of residency duration, the risk was shown to be steadily increasing (p-value =0.008), and in the temporal analysis of the earliest year, the risk was observed to be steadily decreasing (p-value=0.016). In the spatial-temporal analysis, the risk was stably higher in Chiang Rai and Nan provinces compared to Chiang Mai province. According to the display movement over time, the odds of developing cervical cancer declined in all provinces. Conclusions: The risk of cervical cancer has decreased over time but, in some areas, there is a higher risk than in the major province of Chiang Mai. Therefore, we should promote cervical cancer screening coverage in all areas, especially where access is difficult and/or to women of lower socioeconomic status.

호텔 객실 판매촉진운영 개선방안에 관한 연구 (A Study On The Methods Of Managerial Improvement Of The Hotel s Room Sales Promotion)

  • 신형섭
    • 한국관광식음료학회지:관광식음료경영연구
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    • 제8권
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    • pp.123-144
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    • 1997
  • This study, by setting the systems of room sale promotion, analyzing the actual status and the present working state with its center on the 'RHotel' that is a special grade-two hotel and the sales promotion activities of each type, intends to understand the presentstatus of the hotel and present its problems and the method for improvement. The strategy of salespromotion and the ineffectivenessof the system organization were found to be imminent in the sales promotion activities as its problems, and the importanceis being not attached to the actual substance rather than to the actualresults, such as the advertisement and publicity strategies, the irrationality of sales personnel controland its evaluation method, and therefore, the goal-oriented control is not being takenad its problems are emerging. Therefore, as an improvement plan, we ought to put the plan of the hotel merchandising into action for customers to buy what they want, the establishment of the customer-oriented sales promotionservice and the communication channel using the brand-new managerial skills, systemaizesales promotion method sand strategies, develop the organizational and systematic strategies develop the organizatinal and systemactic strategies and goods for the sake of the image-making and room sales promotion of hotels, develop the activation ways of flexible operation, and also need to develop the skills of sales promotion. Accordingly, by doing irrationalsales activities in the system and the promotion with its center on the sales promotion department, and it sis urgently required that we streng then the comodity developments fitting the hotel's traits, such as uniformpolicy of cost, mass-communicationactivities for sales promotion, the improvement of non-effectiveness, and advertisement of hotel items, and the publishing of public relation books. Therefore, the best weapon for hotels before other purchaseis to be discriminatized from other competitive hotel with theunderstanding of the psychology and activities of customers, and the communicatin with customers, and to set up organicprograms of sales promotionstrategies. Also we must promote our sales in accordance with the desire of new customers, gater the market information of customers, all the time, and systematize the facility improvement, managerial policy, business strategiescorresponding with the desire of customers. By doing so, we are able to seek, at the same time, both the satis faction of customers and the sales maximization of the hotels that will perfrom the activities of sales promotion and management.

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대구 , 경북지역 여자대학생의 체중조절 방법과 생활 태도에 관한 조사 (A Survey on Weight Control Diets Practiced by College Women in Taegu and Kyung Buk)

  • 박명희;최영선
    • 대한영양사협회학술지
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    • 제4권2호
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    • pp.200-211
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    • 1998
  • Most of college women are interested in their appearances, and those whose body weights are normal or even underweight try to lose weight. Many methods for weight control diets practiced by college women are unsound and irrational so that some side-effects should be watched out. The present study was aimed to investigate methods of diets, food habits, behaviors, and side effects of weight control and to suggest sound weight loss schemes for college women. The subjects were 353 college women living in Taegu and Kyung Buk area, comprising 178 women who have tried weight control diets and 175 women who have not tried diets. The items included in questionnaires were food habits, food behavoirs, food frequency, physical activity status, 24-hour daily activity record, height, weight, etc., and the survey was conducted in September 1997. There was no difference in body mass index between college women who have tried diets(20.1$\pm$2.26) and women who have not tried diets(19.3$\pm$1.58), and 24.2% of those who have tried diets had body mass index under 19. The leading reason for diets was to make better fitting for costumes(67%). While women who have tried diets also tried to exercise more, they tended to overeat than women who have not tried diets. Mean of food habit scores(9.33 vs 9.32) which corresponded to "poor" habit and food frequencies were not different with or without experiences of diets. This indicated that diets were not related to actual changes of food habits and food intakes. Diet methods used frequently by college women were relying on special diet foods(25.4%), fasting(24.9%) and exercise(22.6%). Trying both exercise and diet was practiced by only 5.1% of the subjects who have tried diets. The duration time of diets was mostly in the range of 1 week to 1 month, and the longer diet period was, the more weight loss was. The frequent side effects due to diets were anemia(41.8%) and enervation(23.7%). Activity coefficients were lower in those who have tried diets(1.38$\pm$0.13) than those who have not tried diets(1.41$\pm$0.19). Women who have tried diets spent more time on reading newspapers and magazines and on watching TV. This study indicates that college women who have tried diets practiced irrational diets for weight reduction and experienced undesirable side-effects. Therefore scientific and systematic weight reduction programs accompanying balanced diets and proper exercise with behavior changes should be developed.

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TIMSS 2015 상위국 8학년 과학성취에 미치는 교육맥락변인의 영향력 분석 (Effect Analysis of Educational Context Variables on 8th Grade Science Achievement Among Top-performing Countries in TIMSS 2015)

  • 곽영순;박상욱
    • 과학교육연구지
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    • 제42권1호
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    • pp.66-79
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    • 2018
  • 본 연구의 목적은 TIMSS 2015 결과에서 상위 성취를 보인 5개국(대한민국, 싱가포르, 대만, 홍콩, 일본)에서 8학년 과학성취에 미치는 교육맥락변인의 영향을 비교 분석하고, 이를 통해 우리나라 과학교육 개선을 위한 시사점을 도출하는 것이다. 과학성취에 미치는 교육맥락변인의 영향력을 비교하기 위해 위계선형모형에 의한 분석을 실시하였다. 연구결과에 따르면 우리나라는 학생수준 변인에서 가정의 학습자원, 과학학습에 대한 흥미, 과학에 대한 가치 인식, 학생의 교육기대 수준이 8학년 학생들의 과학성취도에 유의하게 정적인 영향을 미치는 것으로 나타났다. 학교수준 변인에서는 재학생의 경제적 배경, 학교의 학업적 성공 강조가 과학성취도에 유의하게 정적 영향을 미치는 것으로 나타났다. 상위 5개국 결과를 비교하면 가정의 학습자원, 과학학습에 대한 흥미, 학생의 교육기대 수준이 모든 국가에서 과학성취도에 정적으로 유의한 영향을 미치는 것으로 나타났다. 학교변인에서 재학생의 경제적 배경은 일본을 제외한 모든 나라에서 정적으로 유의한 것으로 나타났으며, 학생 특성에 의한 수업 제한은 우리나라를 제외한 모든 나라에서 정적으로 유의한 것으로 나타났으며, 실험보조 인력은 일본과 대만에서 정적으로 유의한 것으로 나타났다. 연구결과를 토대로 우리나라 중학교 과학과 교수학습에 주는 시사점을 학생과 학교의 사회경제적 지위에 따른 교육격차를 완화, 역량교육을 위한 과학 수업혁신, 과학수업에서 탐구실험 활동 내실화 등의 측면에서 제안하였다.