• 유통과학연구
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• 제13권8호
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• pp.97-104
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• 2015

Purpose - This study examines the positive impact of the social distance between producers and users of online content, investigating and analyzing the most popular Web content. In addition, it tries to elicit the matching effect that appears when the individuals'cultural background is consistent with social distance. Research design, data, and methodology - We collected and analyzed actual data about 4,981 videos clips on YouTube, looking at six countries in order to verify the content of this study. Based on the results of the data analysis, the study conducted behavioral measurements on popularity, social distance, culture, and user engagement. The unit of analysis was the content and we collected information about the content producers and the content records. We controlled the views, comments, likes, calendar dates, and ages in the empirical models. The data was collected in 2011, with the records coming from South Korea, Japan, China, U.S., German, and France. A total of 4,980 elements were analyzed in the model. The empirical model estimated is the bivariate negative binomial distribution (NBD) model. Results - It turns out that there is a possibility that the matching effect can be diminished by variables that reflect the psychological involvement of user engagement. This study proposes academic and practical implications based on these research results. This research shows the positive effect of social distance between users and producers on the increased performance of the online content. We find the effect of social distance to be a stronger tendency in collectivism. The collectivists follow their sense of friendship and intimacy in their culture and, the social congruence effect can be found there as well. The effect, however, could erode in a social case where users are motivated by strong intrinsic and psychological factors. In addition, user engagement complicates the process of user decision making regarding the information. Conclusions - This study examines how the differential effects of social distance caused by culture could disappear through user commitment as a complicated user motivation. Some potential implications are as follows. First, a firm in the collectivism culture has to communicate based on the social distance. In fact, most online channels do not have a function that indicates the social distance as measured by favorites or subscribers. This function could help increase the performance of the content in online channels, but this increasing effect can only be found in a collectivist culture. Based on this, the firms have to communicate and announce to users the actual social distance between users and producers. Second, firms should develop a system that discovers the social distance and culture and shows these measures to users and producers, since the congruence effect between social distance and culture is found only for low user engagement. The firms can take the advantage of the congruence effect only for the development of the social distance and culture visualized system.

• 대한교통학회지
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• 제10권1호
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• pp.41-54
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• 1992

The purpose of this thesis is to construct a model to estimate the delay that vehicles arriving randomly will be experienced at an isolated singalized intersection. To do this the following objectives are set in this study: (i) An what distance a random arrival pattern occurs after a platoon of vehicles are dis-charged from the stop line; (ii) A model which estimates the average delay per through-vehicle with respect to the de-gree of saturation; and (iii) The relation between the stepped delay and average approach delay per vehicle. The following are the findings of this study: (i) A random arrival pattern on the first second and third lanes occur 300,400 and 300m downstream from stop line rdspectively. A random arrival pattern on lane group occurs 500m downstream from the stop line ; (ii) A model for the estimation of approach delay has been developed in such a way that up to x=0.7 the delay increases linearly and beyond 0.7 the delay increases rapidly in a form of second order polynomial due to high degree of saturation : and (iii) Approach delay equals approximately 1.21 times of stopped delay.

• Environmental Engineering Research
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• 제13권3호
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• pp.141-146
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• 2008

Transport of Escherichia coli ATCC 11105 through porous media was investigated in this study using two sets of column experiments to quantify the attachment-related parameters (sticking efficiency, attachment rate coefficient and filter factor). The first set of experiments was performed in quartz sand under different ionic strength conditions (1, 20, 100, 200 mM) while the second experiments were carried out in quartz sand mixed with metal oxyhydroxide-coated sand (0, 5, 10, 25%). The breakthrough curves of bacteria were obtained by monitoring effluent, and then bacterial mass recovery and attachment-related parameters were quantified from these curves. The first experiments showed that the mass recoveries were in the range of 13.3 to 64.7%, decreasing with increasing ionic strength. In the second experiments, the mass recoveries were in the range of 15.0 to 43.4%, decreasing with increasing coated sand content. The analysis indicated that the sticking efficiency, attachment rate coefficient and filter factor increased with increasing ionic strength and coated sand content. The value of filter factor in the first experiments ranged from 1.45 e-2 to 6.72 e-2 1/cm while in the second experiments it ranged from 2.78 e-2 to 6.32 e-2 1/cm. Our filter factor values are one order of magnitude lower than those from other studies. This discrepancy can be attributed to the size of sand used in the experiment. The analysis demonstrated that the travel distance of bacteria estimated using the filter factor can be varied greatly depending on the solution chemistry and charge heterogeneity of porous media.

• 한국입자에어로졸학회지
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• 제17권3호
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• pp.43-54
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• 2021

Size distributions of atmospheric particulate matter (PM) and its water-soluble organic and inorganic components were measured between January and February 2021 at an urban site in Gwangju in order to identify the major factors that determine their size distributions. Their size distributions during the study period were mainly divided into two groups. In the first group, PM, NO₃^-, SO₄^2-, NH₄⁺ and water-soluble organic carbon (WSOC) exhibited bi-modal size distributions with a dominant condensation mode at a particle size of 0.32 ㎛. This group was dominated by local production of secondary water-soluble components under atmospheric stagnation and low relative humidity (RH) conditions, rather than long-range transportation of aerosol particles from China. On the other hand, in the second group, they showed tri-modal size distributions with a very pronounced droplet mode at a diameter of 1.0 ㎛. These size distributions were attributable to the local generation and accumulation of secondary aerosol particles under atmospheric conditions such as atmospheric stagnation and high RH, and an increase in the influx of atmospheric aerosol particles by long-distance transportation abroad. Contributions of droplet mode NO₃^-, SO₄^2-, NH₄⁺ and WSOC to fine particles in the second group were significantly higher than those in the first group period. However, their condensation mode contributions were about two-fold higher in the first group than in the second group. The significant difference in the size distribution of the accumulation mode of the WSOC and secondary ionic components between the two groups was due to the influx of aerosol particles with a long residence time by long-distance transport from China and local weather conditions (e.g., RH).

• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 1998년도 The 12th Asia Quality Management Symposium* Total Quality Management for Restoring Competitiveness
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• pp.580-593
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• 1998

2차 반응표면분석을 위한 부분합성계획은 실험 비용이 많이 들거나, 실험 자체가 어려워서 시간의 소비가 많은 경우, 실험오차의 독립추정이 가능할 때 효과적이다. 반응표면분석에서는 회전성과 기울기 회전성을 만족하는 것이 중요하다. 따라서 본 논문에서는 회전성과 기울기 회전성의 관점에서 부분합성계획을 살펴보고 또한 인자의 수와 중심점의 수가 변함에 따라서 어떤 a(중심에서 축점까지의 거리)의 값이 최적의 실험계획이 되도록 하는지를 연구하였다.

• 한국국방경영분석학회지
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• 제33권1호
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• pp.59-74
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• 2007

컴퓨터 시뮬레이션 모델은 일반적으로 복잡할 뿐더러 운용 시 많은 시간이 소요된다. 따라서 분석의 편의를 위해 좀 더 간단한 메타모델을 수립할 필요가 있다. 본 논문에서는 워게임 모델 JANUS를 사용하여 전차 전투 상황을 묘사하고 이에 대한 메타모델을 수립하였다. 메타모델을 수립하기 위해, 데이터 수집방법으로는 8가지의 실험계획법을, 모델링 방법으로는 2차 반응표면분석과 인공신경망을 고려하였다. 수립된 메타모델의 상대적 성능은 예측치의 평균제곱오차를 기준으로 비교하였다. 본 논문에서 고려한 전투상황에 대해서는 대체적으로 2차 반응표면 모형이 인공신경망 모형보다 더 높은 정확도를 보였으며, 실험계획법으로는 직교배열이나 최대최소거리 기준을 적용한 라틴 하이퍼큐브 계획법이 우수한 성능을 보였다.

• 대한임베디드공학회논문지
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• 제18권3호
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• pp.117-124
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• 2023

In the machine vision inspection equipment, diameter measurement is important process in inspection of cylindrical object. However, machine vision inspection equipment requires complex algorithm processing such as camera distortion correction and perspective distortion correction, and the increase in processing time and cost required for precise diameter measurement. In this paper, we proposed the algorithm for diameter measurement of cylindrical object using the laser displacement sensor. In order to fit circle for given four input outer points, grid search algorithms using root-mean-square error and mean-absolute error are applied and compared. To solve the limitations of the grid search algorithm, we finally apply the singular-value-decomposition based circle fitting algorithm. In order to compare the performance of the algorithms, we generated the pseudo data of the outer points of the cylindrical object and applied each algorithm. As a result of the experiment, the grid search using root-mean-square error confirmed stable measurement results, but it was confirmed that real-time processing was difficult as the execution time was 10.8059 second. The execution time of mean-absolute error algorithm was greatly improved as 0.3639 second, but there was no weight according to the distance, so the result of algorithm is abnormal. On the other hand, the singular-value-decomposition method was not affected by the grid and could not only obtain precise detection results, but also confirmed a very good execution time of 0.6 millisecond.

• 대한디지털의료영상학회논문지
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• 제11권1호
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• pp.5-13
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• 2009

There are several reasons to take X-ray in case of inpatients. Some of them who cannot ambulate or have any risk if move are taken portable X-ray at their wards. Usually, in this case, many other people-patients unneeded X-ray test, family, hospital workers etc-are indirectly exposed to X-ray by scatter ray. For that reason I try to be aware of free space scatter dose accurately and make the point at issue of portable X-ray better in this study. kVp dose meter is used for efficiency management of portable X-ray equipment. Mobile X-ray equipment, ionization chamber, electrometer, solid water phantom are used for measuring of free space scatter dose. First of all the same surroundings condition is made as taken real portable X-ray, inquired amount of X-ray both chest AP and abdomen AP most frequently examined and measured scatter ray distribution of two tests individually changing distance. In the result of measuring horizontal distribution with condition of chest AP it is found that the mAs is decreased as law of distance reverse square but no showed mAs change according to direction. Vertical distribution showed the mAs slightly higher than horizontal distribution but it isnt found out statistical characteristic. In abdomen AP, compare with chest AP, free space scatter dose is as higher as five-hundred times and horizontal, vertical distribution are quite similar to chest AP in result. In portable X-ray test, in order to reduce the secondary exposure by free space scatter dose first, cut down unnecessary portable order the second, set up the specific area at individual ward for the test the third, when moving to a ward for the X-ray test prepare a portable shielding screen. The last, expose about 2m apart from patients if unable to do above three ways.

• Journal of Electrical Engineering and Technology
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• 제2권4호
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• pp.434-440
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• 2007

This paper proposes a fault location algorithm for double-circuit transmission lines in the case of single line-to-ground fault. The proposed algorithm requires the voltage and current from the sending end of the transmission line. The fault distance is simply determined by solving a second order polynomial equation which is achieved directly by the analysis of the circuit. In order to testify the performance of the proposed algorithm, several other conventional approaches have been taken out to compare with it. The test results corroborate its superior effectiveness.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.991-997
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• 2003

A flow field around a disc in an optical disc drive is invested using numerical methods. The high-speed rotating disc induces a strong flow field around the disc, which causes the pressure distribution on the surfaces of the disc. The pressure difference between the upper and the lower surfaces causes the deformation of the disc. In the first part of this study, flow fields around a rotating disc and a stationary wall are investigated using a similarity solution method, in order to identify the effect of the distance between the disc and the wall on the pressure distribution on the surfaces of the disc. In the second part, flow field in a slim-type optical disc drive is studied using a commercial code in order to consider the effect of the vortices generated by the local geometry of the drive.