• 한국공작기계학회논문집
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• 제11권5호
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• pp.7-14
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• 2002

In order to achieve high precision machine tools, the research for performance enhancement of feed drive systems is required. Development of the high speed feed drive system has been a major issue for the past few decades in machine tool indestries. Because table levitation system decrease the table weight, an effect of reaction by weight is minimized and lost motion can be removed at maximum. In case fled system is designed with drive motor, ball screw and support bearing load capacity selection, an effect of decrease of the table weight exist. So, the table weight through an effect of decrease call it into the realization of cost down. Stick-slip friction has a great influence on the contouring accuracy of CNC machine tools. In this paper table levitation system has been developed for the stick-slip in a fled drive systems.

• 한국군사과학기술학회지
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• 제16권5호
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• pp.646-652
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• 2013

PRA(Position Reporting Accuracy) for EO/IR(Electro-Optic/Infrared) airborne camera is an important factor in geo-pointing accuracy. Generally, rate table is used to measure PRA of gimbal actuated camera like EO/IR. However, it is not always possible to fix an EUT(Equipment for Under Test) to rate table due to capacity limit of the table on the size and weight of the object(EUT). Our EO/IR is too big and heavy to emplace on it. Therefore, we propose a new verification method of PRA for airborne camera and assess the validity of our proposition. In this method we use collimator, angle measuring instrument, 6 dof motion simulator, optical surface plate, leveling laser, inclinometer and poster(for alignment).

• 한국기계가공학회지
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• 제17권6호
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• pp.130-135
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• 2018

Currently the automobile market is developing eco-friendly vehicles in order to cope with fuel efficiency regulations. Many studies have been conducted to improve travel performance and fuel economy of the environment-friendly vehicles, and vehicle manufacturers study how to manufacture light-weight vehicles for improving fuel economy for both existing vehicles and environment-friendly vehicles. Exemplary light-weight vehicle technologies include optimal design of vehicle body structure which is a light-weight vehicle method by changing component shapes or layout to optimize the vehicle body structure and the new process technology for using new light-weight and very strong materials Various studies.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1659-1662
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• 2003

The mass measurement of solid density standards using weight exchanger is described. KRISS(Korea Research Institute od Standards and Science) has several solid density standards. Their mass have been measured manually only using a mass comparator(Mettler, 1kg - 0.01mg). However, the uncertaity of the manual mass measurement is up to 300 microgarm much more than 32 microgram of advanced NMIS(National Metrology Institutes) for 1 kg silicon sphere which is primary density standards due to an eccentric error and buoyancy correction error. The new system with a weight exchanger is designed and built to improve the measurement accuracy. It comprises a weight exchager, a mass comparator, air density instruments, and application program for automatic measurement. It is evaluated by measuring several elements in an air tight chamber to verify the performance of it.

• 수산해양기술연구
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• 제59권1호
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• pp.28-34
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• 2023

In the anchovy boat seine fishing boat, it is necessary to select other aquatic organisms other than live anchovies, which are the target species of catch. By making a rotating roller sorter using hydraulic pressure, the anchovy sorting amount was compared and the sorting accuracy of the rotary roller sorter, and the discharge speed of butter fish and jerry fish according to the number of roller revolutions were analyzed. The rotating roller sorter increases the weight of the sorted raw anchovy by 54%, 74% and 91.5% compared to the round bar fixed type, so it can reduce the required time by an average of 73.2%. As a result of converting the sorting accuracy to the weight of pure anchovies excluding the catch weight, the round bar fixed type was 89%; however, the average of the rotating roller sorter was 97.7%. Thus, the sorting accuracy of the rotary roller sorter was further improved by about 8.7%. The roller speed moved 7% at 300 rpm, 7.5% at 600 rpm, and 16% at 900 rpm, so butter fish were discharged overboard 10% faster than jelly fish on average. In addition, the average feed speed of butter fish and jelly fish is 1,400 mm/s when the roller rotation speed is 300 rpm, 1,480 mm/s at 600 rpm, and 1,850 mm/s at 900 rpm. A Φ58 mm roller rotates once it moved about 1.23 mm. In the future, a follow-up study of quantitative evaluation is needed targeting more non-target fish species of anchovy boat seine.

• 인터넷정보학회논문지
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• 제12권5호
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• pp.11-19
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• 2011

본 논문에서는 계층적 QoS 라우팅을 위해 소스 라우팅 방식을 채택하고 있는 전달망에서 집단화된 링크 상태 정보의 정확성을 높이기 위한 서비스경계라인 근사법을 제안한다. 이 방법은 기존 집단화 과정에서 몇몇 경로 가중치들의 소멸로 높아지는 정보 왜곡을 줄이기 위해 주요 경로 가중치를 선정한 후 집단화 정보와 함께 외부망에 전달하는 것으로 지연과 대역폭을 동시에 QoS 파라미터로 갖는 집단화에 유용하다. 본 논문에서는 주요 경로 가중치를 가외치(outlier)로 정의한다. 제안 방법은 링크 당 집단화된 상태 정보를 저장하기 위해서 2k+5개의 파라미터를 갖는다. k는 가외치 개수로 가외치 선정 방법에 따라 달라진다. 모의 실험 결과 제안 방법이 가외치 선정이란 특수성 때문에 기존 방법들에 비해 1.5~2배 이상의 저장 공간을 갖지만 저장 공간과 정보 정확성 증가 비율로 고려한다면 제안 방법이 정보 정확성이 높음을 알 수 있었다.

• 대한지역사회영양학회지
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• 제13권1호
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• pp.13-23
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• 2008

This study investigated the association between the weight status of middle school students and the various weight-related characteristics including desired weight, weight perception, weight-related practice, physical activity, and overeating behavior. Questionnaires were administered to 473 middle school students (178 boys and 295 girls) in Daejeon. Boys and girls were divided into three groups respectively; (1) underweight (BMI<$5^{th}$ percentile) (2) normal weight ($5^{th}$ percentile$\leq$BMI<$85^{th}$ percentile) (3) overweight (BMI$\leq85^{th}$ percentile). Using BMI calculated from measured height and weight, 14.0% of boys and 6.8% of girls were underweight, and 16.3% of boys and 14.2% of girls were overweight. However, among this sample of students, 38.4% of boys and 13.6% of girls perceived themselves as underweight and 29.4% of boys and 44.9% of girls perceived themselves as overweight. We found that overweight students reported their body weights lower and their heights higher compared to non-overweight students, resulting in an underestimation of BMI. Based on desired BMI, 79.9% of the girls desired to be underweight and 73.0% of the boys desired to be normal weight. Overweight or normal weight students were less satisfied with their body weights than underweight students. Girls had more weight control experience and concern compared to boys. Overweight girls spent longer times in watching TV compared to non-overweight girls (p < 0.001) and had more overeating behaviors (p < 0.05). Overweight students reported that they ate snacks less frequently than non-overweight students, which may be due to their tendency to report less eating. In conclusion, significant gender differences and weight status differences existed in weight perception, weight satisfaction, and weight control experience and concern. Because perception of overweight is likely to lead to unhealthy eating behaviors and weight control, efforts for adolescents to improve accuracy of weight perceptions and to understand the benefits of being healthier are needed.

• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.640-643
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• 1995

The internal standard method, which is widely used in chromatographic techniques, is applied to the size exclusion chromatography for the on-line determination of dn/dc value of the sample. This method is found to provide the dn/dc value with suitable accuracy in determining the absolute molecular weight and the molecular weight distribution of the polymers when a light scattering detector is used.

• 농업과학연구
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• 제48권4호
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• pp.681-691
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• 2021

The estimated breeding value (EBV) and accuracy of Hanwoo steer (Korean cattle) is an indicator that can predict the slaughter time in the future and carcass performance outcomes. Recently, studies using pedigrees and genotypes are being actively conducted to improve the accuracy of the EBV. In this study, the pedigree and genotype of 46 steers obtained from livestock farm A in Gyeongnam were used for a pedigree best linear unbiased prediction (PBLUP) and a genomic best linear unbiased prediction (GBLUP) to estimate and analyze the breeding value and accuracy of the carcass weight (CWT), eye muscle area (EMA), back-fat thickness (BFT), and marbling score (MS). PBLUP estimated the EBV and accuracy by constructing a numeric relationship matrix (NRM) from the 46 steers and reference population I (545,483 heads) with the pedigree and phenotype. GBLUP estimated genomic EBV (GEBV) and accuracy by constructing a genomic relationship matrix (GRM) from the 46 steers and reference population II (16,972 heads) with the genotype and phenotype. As a result, in the order of CWT, EMA, BFT, and MS, the accuracy levels of PBLUP were 0.531, 0.519, 0.524 and 0.530, while the accuracy outcomes of GBLUP were 0.799, 0.779, 0.768, and 0.810. The accuracy estimated by GBLUP was 50.1 - 53.1% higher than that estimated by PBLUP. GEBV estimated with the genotype is expected to show higher accuracy than the EBV calculated using only the pedigree and is thus expected to be used as basic data for genomic selection in the future.

• 통합자연과학논문집
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• 제4권1호
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• pp.31-37
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• 2011

Various algorithms and system development are being required to support the advanced decision making of navigation information support system because of a serious loss of lives and property accidents by officer's error like as carelessness and decision faults. Much of researchers have introduced the techniques about the systems, but they hardly consider environmental factors. In this paper, We collect the context information in order to assess the risk, which is considered the various factor of the sailing ship, then extract the features of knowledge context, which is to apply the weight of correlation coefficients among data in context information. We decide the risk after the extract features through the classification and prediction of context information, and compare the value accuracy of proposed method in order to compare efficiency of the weighted value with the non-weighted value. As a result of experience, we know that the method of weight properties effectively reflect the marine environment because the weight accurate better than the non-weighted.