• 한국자동차공학회논문집
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• 제16권6호
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• pp.1-9
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• 2008

The current test methods are insufficient to evaluate and ensure the safety and reliability of vehicle system for all possible dynamic situation including the worst case such as rollover, spin-out and so on. Although the known NHTSA J-turn and Fish-hook steering maneuvers are applied for the vehicle performance assessment, they aren't enough to estimate other possible worst case scenarios. Therefore, it is crucial for us to verify the various worst cases including the existing severe steering maneuvers. This paper includes the procedure to search for other useful worst case based upon the existing worst case scenarios mentioned above and its application in simulation basis. The only human steering angle is selected as a design parameter here and optimized to maximize the index function to be expressed in terms of either roll angle or yaw rate. The obtained scenarios were enough to generate the worst case to meet NHTSA worst case definition (ex.2-inch wheel lift). Additionally, as an application, the worst case steering maneuver is acquired for the vehicle to operate with a simple ESP system. It has been concluded that the new procedure in this paper is adequate to create other feasible worst case scenarios for a vehicle system both with an intelligent safety control system and without it.

• 치과방사선
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• 제25권2호
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• pp.389-398
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• 1995

The purpose of this study was to compare the diagnostic performance of Waters' and panoramic view; maxillary sinus posteroanterior and lateral scanography of Scanora/sup (R)/ for mucosal thickening of maxillary sinus as well as to identify the utility of Scanora/sup (R)/ for the detection of maxillary sinus disease. The assessment was done at 66 maxillary sinuses in 45 patients and the results were as follows ; 1. Estimation of presence or absence of mucosal thickening. The sensitivity, specificity, and positive and negative predictive value of maxillary sinus posteroanterior and lateral scanography were 0.865, 0.860, 0.921, and 0.805 respectively and slightly higher than those of Waters' and panoramic views, which were 0.832, 0.835, 0.903, and 0.728 respectively. However, paired t-test showed no significant differences in the diagnostic performance of the two pairs of imaging modalities. 2. Estimation of the types of mucosal thickening. The diagnostic accuracy for type I, II, III was 75.3％ on Waters' and panoramic view; 77.9％ on maxillary sinus posteroanterior and lateral scanography. It was higher on the latter ,but showed no significant differences from that on the former. 3. Reliability of interpretation. In itraobserver and interobserver agreement, both overall rates of agreement and kappa-value were slightly higher on maxillary sinus posteroanterior and lateral scanography than on Waters' and panoramic views. There was no significant differences between the two pairs of imaging modalities. These results suggested that scanogram is a useful diagnostic radiography as well as Waters' and panoramic views for detection of maxillary sinusitis.

• 한국건설관리학회논문집
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• 제19권4호
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• pp.82-92
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• 2018

건설사업 초기단계가 환경부하량의 절감 가능성에 큰 영향을 미친다는 것을 감안한다면, 효과적인 의사결정을 지원할 수 있는 시스템을 초기에 구축하고 활용하는 것이 중요하다. 이에 본 연구에서는 기본적인 설계 요인들을 고려하여 초기 설계단계에서 활용될 수 있는 환경부하량 산정 모델을 구축하였다. 이 모델은 인공신경망 기법을 활용하고 설계단계 업무가 진행됨에 따라 얻을 수 있는 가용정보 수준을 고려하여 기획단계 적용 모델(ANN-1)과 기본 설계단계 적용 모델(ANN-2)로 구분하여 환경부하량을 산정하도록 구축되었다. 모델의 실험결과 ANN-1, ANN-2모델의 절대평균오차율과 표준편차는 각각 11.19% / 5.30% 및 9.59% / 3.09%로 높은 신뢰성을 갖는 것으로 나타났다. 본 모델은 프로젝트 초기단계별 기초적인 가용정보만을 활용하여 신속하고 정확하게 환경부하량을 추정하고 합리적인 의사결정을 지원할 수 있을 것으로 기대된다.

• 대한치과기공학회지
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• 제38권4호
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• pp.353-363
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• 2016

Purpose: This study aims to assess clinical practice satisfaction among dental technology students and to identify the factors that may influence their career decision levels. In doing so, the present study provides preliminary data as to ways to improve clinical practice satisfaction levels and career decision levels that would be optimal for one's competence. Methods: he survey was conducted on dental technology students. The collected data was analyzed by the statistical program SPSS 21.0. The results were analyzed by reliability, frequency, multiple-way ANOVA, correlation, multiple regression. To test for significance on each item, p<0.05 has been decided as a standard. Results: Analysis results indicate that the factors influencing clinical practice satisfaction of dental technology students include school year, satisfaction of major, area of clinical practice, and assigned department for clinical practice, while the factors that influence career decision levels include satisfaction of major and clinical practice satisfaction. Conclusion: Results of present study suggest that in order to improve clinical practice satisfaction among dental technology students and thereby career decision levels, one needs to focus on satisfaction of major and quality of clinical practice. Such efforts will enable a more active and effective approach toward clinical practice for the dental technology students, and with appropriate understanding and assessment of the experience, they will be better equipped to make a career decision where they can live up to their competence.

• 한국의류학회지
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• 제25권6호
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• pp.1025-1036
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• 2001

This paper explores the effects of price discount frequency on consumer evaluation of clothing brand equity as well as the impact on consumers who exhibit different consumer characteristics. Following a preliminary investigation, two clothing brand groups were identified according to the frequency of their price discounts, one with a high frequency of price discounts, the other with a low frequency. Each brand group consisted of three women's clothing brands. A questionnaire was developed and administered to 351 females between the ages of nineteen and thirty-four in October 2000. The questionnaire included questions on evaluations on clothing brand equity (i.e., perceived quality, brand image, perceived value, reliability and brand knowledge), on consumer characteristics (i.e., clothing knowledge, clothing evaluative criteria, price perception and demographic characteristics), as well as on price discount frequency. Statistical tests, such as factor analysis. t-test and pearson's correlation, were used to analyze the data. Results of this research showed that price discount frequency negatively impacted consumer perception of clothing brand equity. The negative influence was particularly strong on the perceived quality and brand image dimensions of brand equity. The findings also suggested the effect of price discount frequency on consumer assessment of clothing brand equity was related to consumer characteristics as well. The equity of the clothing brand group with a low frequency of price discounts was positively related to clothing knowledge, price-quality inference, price-prestige inference, sale prone-ness. price mavenism, valuing the fashionable and symbolic uses of clothing and family income. On the other hand, it was negatively related to low price consciousness. The equity of the clothing brand group with a high frequency of price discounts was positively related to utilitarian economic aspects of clothing values as well as to low price consciousness. To establish and maintain high brand equity, marketers must pay attention to the frequency of price discount as it may have a negative impact on clothing brand equity.

• 대한산업공학회지
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• 제39권6호
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• pp.486-497
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• 2013

In this paper, we first present an in-depth survey of the research on Verification, Validation and Accreditation (VV&A) applied in various areas. Then we introduce the characteristics of the military and defense Modeling and Simulation (M&S) and propose the direction of method for VV&A with the identified characteristics. The M&S has been widely used in many different applications in the military and defense area including training, analysis, and acquisition. Methods and processes of VV&A have been proposed by researchers and M&S practitioners to guarantee the correctness of the M&S. The idea of applying the formal credibility assessment in VV&A is originated from the Software Engineering Reliability Test and Systems Engineering Development Process. However, the current VV&A techniques and processes proposed in the research community have not utilized the military-and-defense specific characteristics. We identify the characteristics and issues that can be found in the military and defense M&S. Then propose the direction of techniques and methods for VV&A considering the characteristics and issues. Also, possible research direction on the development of VV&A is proposed.

• 드라이브 ㆍ 컨트롤
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• 제13권2호
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• pp.19-25
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• 2016

Recently, drivers have begun to regard comfort in the cabin as one of the most important factors in construction equipment like forklifts. Accordingly, it has become more important to design a forklift cabin with a better sound quality as well as lower sound level, which can make a driver more comfortable. In this paper, the correlation between subjective evaluation and Zwicker's sound quality index was analyzed through a blind test by a few workers in forklifts and other construction equipment in several countries. Correlation analysis showed that Loudness and Sharpness were ranked in sequence, and tendencies were different from country to country. Also, contribution analysis for Loudness and Sharpness using operational transfer path analysis (OTPA), which is widely used in the field of noise, vibration, and harshness (NVH), was performed. However, Loudness and Sharpness cannot be used with OTPA directly because there are no linear relationships between the sources and receivers. In this paper, both are calculated by applying the DIN 45631 method with a contribution rate (%) of 1/3 Octave Sound Pressure Level by OTPA method in addition to considering spectral masking.

• 대한물리의학회지
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• 제14권2호
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• pp.125-135
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• 2019

PURPOSE: This study examined the effects of low frequency neuromuscular electrical stimulation (NMES) training on abdominal obesity in middle-aged women through electromyography and ultrasound. METHODS: Twenty-two middle aged women with abdominal obesity participated in the study. A low-frequency NMES device was used on the abdomen and waist of each subject for 20 minutes each (a total of 40 minutes) three times a week for eight weeks. The waist-hip ratio (WHR), weight and BMI (Body Mass Index) were measured. Electromyography (EMG) and ultrasound measurements were performed three times in total (pre-intervention, four weeks into the intervention, and eight weeks post-intervention) to examine the effects of low-frequency NMES on the abdominal muscle activity, muscle thickness, and subcutaneous fat. RESULTS: The results indicated a difference in the WHR and waist circumference before and after intervention (p<.05). The external oblique muscle (EO) showed a significant increase in muscle activity during all measurements taken post-intervention (p<.05). The abdominal subcutaneous fat thickness also showed a significant decrease between each measurement (p<.05). The test results showed that the abdominal subcutaneous fat thickness values taken eight weeks post-intervention were significantly lower than those taken pre-intervention and four weeks into the intervention (p<.05). CONCLUSION: These findings show that low-frequency NMES device training can be applied to middle-aged women with abdominal obesity to improve their body shape and exercise performance.

• 대기
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• 제32권4호
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• pp.367-379
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• 2022

In this paper, the evaluation of the performance of Korea Meteorological Administratio (KMA) Global Seasonal forecasting system version 6 (GloSea6) is presented by assessing the effects of larger ensemble size and carrying out the test using different initial conditions for hindcast in sub-seasonal to seasonal scales. The number of ensemble members increases from 3 to 7. The Ratio of Predictable Components (RPC) approaches the appropriate signal magnitude with increase of ensemble size. The improvement of annual variability is shown for all basic variables mainly in mid-high latitude. Over the East Asia region, there are enhancements especially in 500 hPa geopotential height and 850 hPa wind fields. It reveals possibility to improve the performance of East Asian monsoon. Also, the reliability tends to become better as the ensemble size increases in summer than winter. To assess the effects of using different initial conditions, the area-mean values of normalized bias and correlation coefficients are compared for each basic variable for hindcast according to the four initial dates. The results have better performance when the initial date closest to the forecasting time is used in summer. On the seasonal scale, it is better to use four initial dates, where the maximum size of the ensemble increases to 672, mainly in winter. As the use of larger ensemble size, therefore, it is most efficient to use two initial dates for 60-days prediction and four initial dates for 6-months prediction, similar to the current Time-Lagged ensemble method.

• 대기
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• 제32권4호
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• pp.277-295
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• 2022

The global weather prediction model, Korean Integrated Model (KIM), has been in operation since April 2020 by the Korea Meteorological Administration. This study assessed the performance of heat waves (HWs) in Korea in 2020. Case experiments during 2018-2020 were conducted to support the reliability of assessment, and the factors which affect predictability of the HWs were analyzed. Simulated expansion and retreat of the Tibetan High and North Pacific High during the 2020 HW had a good agreement with the analysis. However, the model showed significant cold biases in the maximum surface temperature. It was found that the temperature bias was highly related to underestimation of downward shortwave radiation at surface, which was linked to cloudiness. KIM tended to overestimate nighttime clouds that delayed the dissipation of cloud in the morning, which affected the shortage of downward solar radiation. The vertical profiles of temperature and moisture showed that cold bias and trapped moisture in the lower atmosphere produce favorable conditions for cloud formation over the Yellow Sea, which affected overestimation of cloud in downwind land. Sensitivity test was performed to reduce model bias, which was done by modulating moisture mixing parameter in the boundary layer scheme. Results indicated that the daytime temperature errors were reduced by increase in surface solar irradiance with enhanced cloud dissipation. This study suggested that not only the synoptic features but also the accuracy of low-level temperature and moisture condition played an important role in predicting the maximum temperature during the HWs in medium-range forecasts.