• 한국공작기계학회논문집
• /
• 제16권4호
• /
• pp.101-107
• /
• 2007

The objective of this research work is to investigate into effects of an auto tracking of the focal distance on the quality of the cut part in the cutting of a low carbon sheet using a high-power CW Nd:YAG laser. An auto-tracking system with a capacitance based distance control loop has been employed to perform a real control of the focal distance. In order to examine the influence of the auto-tracking of a focal distance on the optimum focal distance, the kerfwidth, surface roughness and the formation of the cut section, several linear cutting tests have been carried out using the auto-tracking system. The results of experiments have been shown that the optimum focal distance is 0.9mm. In addition, it has been shown that the variation of kerfwidth and the surface roughness of the cut part with control of the focal distance are reduced 40-80% and 30-55% in comparison with those of the cut part without tracking of the focal distance. From the results of the experiments, it has been found that the real time tracking of the focal distance can improve the part quality.

• 한국수학교육학회지시리즈D:수학교육연구
• /
• 제6권2호
• /
• pp.145-158
• /
• 2002

Recently a new type of educational method through the internet, distance education, has been developed with technology development. To find out any complement between distance education and traditional in-class education, a series of study with junior high school mathematics were conducted. Both distance education and in-class education have merits and shortcomings. Some advantages with distance education shown from the study can be used for complement to in-class education depending on the contents and subjects. Distance education in mathematics education can be a good turning point for future education.

• 유통과학연구
• /
• 제18권3호
• /
• pp.99-106
• /
• 2020

Purpose: The purpose of this study is to investigate the influence of perceived risk and psychological distance on purchase intention when purchasing a gift. It focuses on social distances and temporal distances, and aims to identify the interactions between these psychological distances and perceived risk. Data were collected through experiments. Research design, data and methodology: The experiment was carried out through the design of 2 (perceived risk: high/low) × 2 (social distance: far / near) × 2 (temporal distance: far / near) between-subjects design. Participants were 241 undergraduates from two universities in Chungnam and Gangwon, and randomly assigned to one of eight groups. Results: It was confirmed that there is a difference in purchase intention according to the risk perceived by consumers when purchasing a gift. In particular, the difference in purchase intention based on the risk perceived by the buyer was found to be greater as the social distance between the gift giver and the recipient is shorter. In addition, it was confirmed that the intention to purchase a gift was simultaneously influenced by three factors: social distance, perceived risk, and time remaining to purchase a gift. In other words, when both temporal distance and social distance were short, the difference in purchase intention according to perceived risk was greatest. Conclusions: The purpose of this study was to examine how the relationship between perceived risk and purchase intention when purchasing a gift varies with psychological distance. This study found that the closer the relationship between the gift purchaser and the beneficiary and the shorter the time remaining before the gift purchase, the greater the difference in the willingness to purchase due to the perceptual risk. In practice, the results of this study can be used to establish sales promotion strategies for various gift products. Above all, the closer the relationship between the gift buyer and the person receiving the gift, the more differentially there should be a guarantee program that can reduce or eliminate the risk perceived by the buyer. There is also a need to use step-by-step product recommendation programs that can reduce perceptual risk depending on the time remaining until a particular season, such as graduation or Christmas.

• 한국광학회지
• /
• 제17권6호
• /
• pp.537-543
• /
• 2006

단일 줌 카메라를 사용한 거리추정 방법은 시야 범위가 광 축으로 제한되기 때문에 거리 추정에는 한계가 있다. 본 논문에서는 넓은 범위에서 거리추정을 위한 수평이동 방식의 줌 렌즈를 이용한 입체영상에서의 물체의 거리 추정 방법을 제안한다. 거리 추정을 위하여 줌렌즈를 이용한 수평이동방식 카메라를 구현하였다. 제안한 방법으로 또한 편광 입체영상 모니터를 사용하여 카메라의 좌, 우 영상 정보를 획득하였다. 인간이 볼 수 있는 시야 범위를 추정하기 위해 좌, 우로 $0mm{\sim}500mm$ 범위에서 실 거리와 추정 거리를 구하였고 이의 오차는 10mm 미만이었다. 입체 카메라의 주시각 제어에 줌 기능을 사용하여 제어의 오차를 줄였기 때문에 주시각에 의한 거리 추정에서 보다 더욱 정확한 거리를 추정 할 수 있었다. 또한 교차방식과 수평이동방식의 거리 추정의 오차를 비교하여 수평이동 방식이 교차방식보다 더욱 정확한 거리 정보를 추정을 확인하였다.

• 한국전문물리치료학회지
• /
• 제17권1호
• /
• pp.36-42
• /
• 2010

The aim of this study was to investigate effects of reaching distance on movement time and trunk kinematics in hemiplegic patients. Eight hemiplegic patients participated in this study. The independent variables were side (sound side vs. affected side) and target distance (70%, 90%, 110%, and 130% of upper limb). The dependent variables were movement time measured by pressure switch and trunk kinematics measured by motion analysis device. Two-way analysis of variance with repeated measures was used with Bonferroni post-hoc test. (1) There were significant main effects in side and reaching distance for movement time (p=.01, p=.02). Post-hoc test revealed that there was a significant difference between 110% and 130% of reaching distance (p=.01). (2) There was a significant main effect in side and reaching distance for trunk flexion (p=.01, p=.00). Post-hoc test revealed that there were significant differences in all pair-wise reaching distance comparison. (3) There was a significant side by target distance interaction for trunk rotation (p=.04). There was a significant main effect in target distance (p=.00). Post-hoc test revealed that there were significant differences between 70% and 110%, 70% and 130%, 90% and 110%, 90% and 130% of target distance. It was known that trunk flexion is used more than trunk rotation during reaching task in hemiplegic patients from the findings of this study. It is also recommended that reaching training is performed with limiting trunk movement within 90% of target distance whereas reaching training is performed incorporating with trunk movement beyond 90% of target distance in patients with hemiplegia.

• 아태비즈니스연구
• /
• 제15권3호
• /
• pp.495-507
• /
• 2024

Purpose - The purpose of this study was to analyze the impact of cultural distance, economic distance, and geographic distance on the export of Korean broadcasting programs by using data from 2013 to 2022 between Korea and nine regions in the Asia-Pacific. Design/methodology/approach - This study conducted a panel regression analysis using pooled cross-sectional time series data extracted from a ten-year dataset of nine Asia-Pacific regions: Japan, China, Taiwan, Singapore, Hong Kong, Vietnam, the Philippines, Indonesia, and Thailand, which are the main export destinations for Korea broadcasting programs. Findings - Firstly, economic and geographic distance, key determinants in the traditional gravity model, were found to significantly influence the export of Korean broadcasting programs. Secondly, while cultural distance showed a positive correlation with the export value of Korean broadcasting programs, an non-linear inverted U-shape relationship was observed when considering the squared term of cultural distance. Research implications or Originality - The findings of this study contribute to the existing literature by providing empirical evidence that the factors influencing the traditional gravity model remain significant determinants of Korean broadcasting program exports. While previous studies have primarily emphasized economic variables, this study underscores the importance of cultural factors in explaining the export of Korean broadcasting programs.

• 대한전기학회논문지:전력기술부문A
• /
• 제50권9호
• /
• pp.411-416
• /
• 2001

Distance relay is the most widely used in transmission line protection because it is applicable not only as main protection but also as back-up protection. However, the protection range of the distance relay is always fixed in the unchangeable operating range while the power system varies, and therefore the distance relay is the device that is the highly influenced by the power system changes. In this regard, this paper describes an approach to minimize the mal-operation of the distance relay due to the power system changes through changing protection range of the distance relay into optimal condition in response to the load variation and power system condition. Also mal-function of the distance repay in case of high resistance ground faults could be minimized through modeling the protection range into quadratic function.

• 한국컴퓨터산업학회논문지
• /
• 제8권3호
• /
• pp.155-166
• /
• 2007

본 연구에서는 얼굴 영상을 캡쳐하여 전 처리한 후 얼굴영역을 분리하고, 분리된 얼굴 영역에서 미분 연산자와 최소 형태를 세선화하여 특징을 추출하였다. Hough Transform은 $r-\theta$ 평면에서 직선의 기울기와 절편으로 변환되며, 반면 Housdorff distance는 세선화된 영상에서 선분을 추출하여 길이, 회전, 천이 특징을 추출하였다. 사람마다 다른 특징들을 추출하여 Housdorff distance과 Hough Transform에 관하여 비교분석 결과 Hough변환의 복잡도가 더 적은 것으로 판단되었다. 인식율은 Housdorff Distance를 이용한 인식율이 Hough Transformation에 비해 조금 높게 나타났다.

• Educational Technology International
• /
• 제17권1호
• /
• pp.59-85
• /
• 2016

The purpose of the study is to report differences in the effects of learner characteristics on the self-regulated learning (SRL) abilities between Chinese and Korean distance learners by using a structured SRL scale. A standardized 54-item self-regulated learning scale (SRAS) was used. The reliability was tested both in China and Korea which showed the scale had good reliability. The comparative study were conducted by administering the SRAS on 1999 Chinese distance learners from the Open Distance Education Center of Beijing Normal University and 1941 Korean distance learners from H Cyber University. Data on four dimensions of SRL - planning, control, regulating, and evaluation - were analyzed using 't-test' and 'ANOVA' with regards to the learner characteristics such as gender, age, prior education level, semesters, location and major. Results indicated that the average participant had an above medium level of SRL ability in all of the four dimensions. There were significant differences in the self-regulated learning ability between Chinese and Korean distance learners. Chinese distance learners scored higher in SRAS than Korean distance learners. The effects of learner characteristics on the SRL ability showed different patterns in the two countries. As for gender, male learners scored better in SRL than female learners in China, whereas it was just the opposite in Korea. No age differences were found in China, but Korean data exhibited a consistent age effect in all dimensions. In Korea, the age group older than 46 scored the highest, followed by the group between 35 to 45 years old, the group between 26 to 35 years old and the group younger than 25. As for location, Korean distance students from metropolitan were better than those from other regions, whereas it was on the contrary in China, albeit the location effect was not statistically significant. Prior education level had a clear and consistent effect on the SRL ability in both countries: the distance learners from junior colleges had better planning, regulating and evaluating abilities than those who came from senior high schools. These results have been discussed in various contexts of distance/online education as well as in relation to different culture between China and Korea. The results will also have implications for designing distance and online learning generally.

• 치위생과학회지
• /
• 제23권2호
• /
• pp.123-131
• /
• 2023

Background: As a restorative material used to treat dental caries, the light-curing type resin is widely used, but it has the disadvantage of polymerization shrinkage. The Bulk-Fill composite resin was developed to solve these shortcomings, but the existing research mainly focused on comparing the physical properties of a composite resin and a Bulk-Fill resin. A study on the light curing time and distance of the Bulk-Fill resin itself tend to be lacking. Methods: This study compares the surface microhardness of specimens prepared by varying the light curing time and distance of smart dentin replacement (SDR) as a flowable Bulk-Fill resin and Tetric N-ceram as a packable Bulk-Fill resin, and confirms the polymerization time and distance that becomes the optimum hardness. To determine the hardness of the specimen, it was measured using the Vickers Hardness Number (Matsuzawa MMT-X, Japan). Results: In SDR, the surface microhardness decreased as the distance increased in all time groups in the change distance from the curing tip. In the change of light curing time with respect to the distance from curing tip, the surface microhardness increased as the time increased. In Tetric N-ceram, the surface microharness showed no significant difference in the change of the distance of curing tip in the group of 20 and 60 second. But in the group of 10 and 40 seconds, decreased as the distance increased. The surface microharness increased as the light curing time increased in all distance groups. Conclusion: When using SDR and Tetric N-ceram in clinical practice, it is considered that as the distance from the polymerization reactor tip increases, a longer light curing time than the polymerization time recommended by the manufacturer is required.