• Journal of Chest Surgery
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• v.36 no.1
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• pp.15-20
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• 2003

Myasthenia gravis is a rare autoimmune disease involving acetylcholine receptor and its autoantibody on neuromuscular junction. The methods of treatment are medical treatment and surgical thymectomy. In this paper we analyzed the result of thymectomy and the factors affecting the postoperative symptom improvement. Material and method : This study obtained medical records of 37 patients who received the thymectomy for myasthenia gravis from March 1986 to December 1998. Result Out of 37 cases, 21 cases(57%) showed improvement, of which 8 cases (50%) in the group of thymoma(n=16), and 13 cases (62%) in the group of thymic hyperplasia(n=21) showed the improvement of symptoms. Postoperative complications were respiratory insufficiency due to aggravation of symptoms after operation, including tracheal intubation for ventilator support in 9 cases, pneumonia in 3 cases, pneumothorax in 2 cases and left vocal cord palsy in 1 case. There was one postoperative mortality. The relation between postoperative improvement and sex(P=0.3222), age(P=0.7642), thymic pathologic variants,(P=0.4335) and classification of thymoma(P=0.20) showed no statistically significant correlation. However, the lower grade of preoperative symptoms can predict the lower grade of postoperative symptoms significantly(P=0.0032). Follow up study to 36 postoperative survivors was performed in October 2002 based on the out-patient records and call with patients. Out of 36 cases, 33 cases(91.7%) could be investigated and 3 cases could not. Mean follow up period was 83.2 months. Out of 33 cases, 25 cases(75.8%) showed symptomatic improvement, of which 8 cases(53.3%) in the group of thymoma(n=15) and 17 cases(94.4%) in the group of thymic hyperplasia(n=18) showed the improvement of$\boxUl$ symptoms. Conclusion : In myasthenia gravis, thymectomy showed the good improvement, and more important factor affecting the improvement of symptoms was the grdae of preoperative symptoms. Also midterm and long term follow up results showed good symptomatic improvement.

• The Journal of Internal Korean Medicine
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• v.15 no.1
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• pp.152-164
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• 1994

In Nai-Gyung(內經), it is said that In-Yeong(人迎) means In- Yeong Maek(人迎脈), Gi-Gu m- eans Tson-Gu(寸口) or Maek- Gu(脈口), In-yeong, artery in the side of neck, is located before Yeong-Geun(瓔筋), called as Jok-Yang-Myung-Maek(足陽明脈),so the part of In-Yeong-Maek means In-Yeong-Hyul(人迎穴) of Jok-Yang-Myung- Wi-Gyung(足陽明胃經) showing the artery in the side of neck. The part of Tson-Gu-Maek is that of artery in Yo-Gol(橈骨), beating source of Soo-Tae-Eum-Maek (手太陰脈) Of In-Yeong-Gi-Gu-Maek, In-Yeong-Maek mainly consists of Yang(陽), Gi-Gu-Maek of Eum(陰), so In-Yeung means physical disease, short of extra Eum component. They said that if In-Yeong-Maek was more than Gi-Gu-Maek, it meant physical injury, while Gi-Gu-Maek was more than In- Yeo-ng-Maek, it meant internal injury. In-Yeong-Gi-Gu-Maek is the one to distinguish the external and internal, the inside and outside, Eum and Yang, but there is no definite classification method to distinguish it, also it is difficult to grasp the comparison of 1sung(1盛), 2sung(2盛), 3sung(3盛), interrelation with 12-Gyung-Rak(l2經絡), change of maek phases, so necessary to set up the clear definition for In-Yeong-Gi-Gu-Maek. For the two theories as to In-Yeong-Gi-Gu-Maek according to Nai-Gyung, the one is to diagnose the maek by comparing the In-Yeong-Hyul with Tson-Gu of Soo-Tae-Eum-Maek as Gi-Gu in the both sides of neck part, he other is to divide the left and right of Gi-Gu-Maek in to In-Yeong and Gi-Gu afterwards, but today it is difficult to compare and explain the medical theory afterwards owing to insufficient consideration of In-Yeong-Gi-Gu-Maek at Nai-Gyung. The diagnosis of In-Yeong-Gi-Gu-Maek at Nai-Gyung to distinguish the surplus and shortage of Eum and Yang up to now since Nai-Gyung has so important and diagnostic value as to grasp the exact meaning. Herewith, this researcher com-pared Nai-Gyung and medical theory afterwards, reported it to consider the fixed position and changing process of viscera and entrails arrangement of literatures introducing In-Yeong-Gi-Gu-Maek, examining the change of maek phases for normal maek and a-bnormal maek of In-Yeong-Gi-Gu-Maek, considering the 1 sung, 2 sung, 3 sung maek phases in In-Yeong-Gi- Gu-Maek. According to the above results, the conclusion was reached as follows. 1. In-Yeong as the outside indicates external disease(外感), showing the surplus and shortage of Yang symptom by having Boo-Maek(浮脈) as Py-ung-Maek(平脈), Gi-Gu as the inside indicates internal disease(內傷), showing the surplus and shortage of Eum symptom by having Chim-Maek(沈脈) as P-yung-Maek(平脈). 2. In Pyung-Maek of In- Yeong-Maek as Boo-Maek, g-radual sinking of more floated changing maek because of disease means the improvement of di-sease, in Pyung-Maek of Gi- Gu-Maek as Chim- Maek, gradual floating of more sunken changing maek because of disease means the improvement of disease. 3. They said that disease of Jok-Gyung-Rak(足經絡) is cha-nged to that of Soo-Kyung-Rak(手經絡) when Jo-Maek(躁脈) appears whether In-Yeong-Maek or Gi-Gu-Maek 4. With the exemples of 1 sung 2 sung 3 sung it was porned with the relation of Pyo-Ri-Soo-Jok(表裏手足). Therfore I can guess that this fact is a moment explained the Bu-You-Sa-Kyung(部有四經) mentioned in Nan-Gyung-18-Nan(難經 第18難). 5. I think that In-Yeong and Gi-Gu, as a diagnosis method which distinguish between the inside indicates internal disease and the outside indicates external disease, is required to study further researches.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.1
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• pp.1-10
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• 1982

Degree of grain shattering which is of varietal character is an important determinant for the magnitude of field loss of grains during harvest and threshing. Seven Indica \times Japonica progeny varieties and four Japonica varieties were subjected to measurements of tensile strength of grains, degree of grain shattering when panicles were dropped at 1.5m above concrete floor, and moisture content of grains (wet basis) during a period 35 to 63 days after heading. In addition, two varieties were tested for the relation of tensile strength of grains to the magnitude of field loss of grains in actual binder harvest. The 11 varieties differed conspicuously in tensile strength of grains and the degree of grain shattering: the weakest average tensile strength of grains of a variety was about 90g and the strongest about 250g with varying standard deviation of 30 to 60g. Three Indica \times Japonica varieties and one Japonica variety shattered I to 30% of the grains under the falling test. The threshold tensile strength of grains allowing grain shattering was estimated to be 180g on average for a sampling unit of 10 panicles, but only the grains having tensile strength weaker than 98g within the samples shattered. A decrease in average tensile strength by 10g below the threshold value corresponded to an increase of 3 to 5% in grain shattering. Most varieties did not change appreciably the tensile strength of grains and degree of grain shattering with delay in time of harvest and showed a negative correlation between the tensile strength and the moisture content of grains. The average tensile strength of grains was negatively correlated linearly with field loss in binder harvest. The average tensile strength for zero field loss in binder harvest was estimated to be 174g and a decrease in the average tensile strength by 10g corresponded to an increase of 40kg per hectare in field loss of grains. Instead of the average tensile strength of grains, the percentage of grains having tensile strength weaker than 100g is recommended as a criterion for the estimation of field loss of grains during harvesting operations as well as a basis of variety classification for grain shattering, since the standard deviation of tensile strength of grains varies much with variety and time of harvest, and individual grains having tensile strength stronger than 98 did not shatter practically.

• Journal of the Korean Chemical Society
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• v.53 no.5
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• pp.570-584
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• 2009

The purpose of this study was to find out high school students' perception on psychologicallearning environment generated by science teachers and their attitude change related to science. The subjectsconsisted of 539 freshmen in a boys' high school pre-applied of common school group in S city. This study wasconducted with students' perception survey and classification of teachers' features according to it. The surveyabout science-related attitude was also made in early 1st semester and 2nd semester, and the students showingthe great attitude change related to science were interviewed. The results of this study revealed that statistically,students had a more positive perception on female teachers than on male ones and that according to their teachers,there were clear different in the psychological learning environment perceived by students. As for the relation of teachers' features and students' attitude change, it showed the negative effect only when the teacher was incharge of only one class, but in most of the cases, there was no meaningful correlation. The semi-structuredinterview with students with great attitude change related to science indicated that the main cause of the changewas the achievement they made in class. The interview showed that the change related to science happenedunder the indirect influence of teachers rather than direct influence. Furthermore, students wanted scienceteachers to meet the science class possessing various instruction behaviors and support behaviors. Therefore,science teachers playing an important role in students' choice of career should make efforts to realize thelearner-centered curriculum and change students' science-related attitude into a positive direction.

• Journal of the Korean Geographical Society
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• v.47 no.1
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• pp.60-78
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• 2012

The main objective of this study is to conduct subnational population projections of Korea based on a Myriad Things" (萬物門), which is part of Seongho's representative work entitled $Miscellaneous$ $Explanations$ $of$ $Seongho$ (星湖僿說), has been in this paper in order to understand Seongho's "thinking on geography". To do so, contents related to geography were selected and these were discussed and interpreted in terms of the classification system of today's geographical knowledge. Following is the result of this research. First, information on astronomical geography and natural geography such as uplift, tornado, structure of soil, and the $yut$ board as well as humangeographical topics such as wild $ginseng$, cigarettes, hot pepper, traditional fruits and nuts (chestnuts, jujubes, and persimmons), Goryeo paper (Korean paper), mulberry trees, cotton plants, natural dye, policy about horses, magnetic compass needles, and farming implements for rice transplantation are mentioned in "Myriad Things" in relation to geography. Second, the depth of information described varies from topic to topic, but the topics on tornado and magnetic compass needles, horses, wild ginseng, traditional fruits and nuts, and $yut$ board are described in depth and in detail. Third, authenticity of the contents on these topics are "true" insofar as bibliographical information and citations are provided for support. Fourth, these topics reflect the interests and circumstances that are related to the "economic improvement of common people's livelihood" in those days, such as agriculture, crops, and transportation of goods. Fifth, the bibliography and citations explaining all instances reveal that China (Qing) is a great civilization of the advanced world and that the scholarship of Joseon relied on and accepted it. Sixth, except for horse raising and management, farming implements for rice transplantation, sericulture, and natural dying of cloth, most of the topics are useful even today. In short, theres is a profound aspect to the content that makes it possible to estimate the "geographical thinking". In general, the focus of the content of this book directly linked to the practical agricultural economy of the common people.

• Journal of Intelligence and Information Systems
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• v.22 no.4
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• pp.177-192
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• 2016

Machine learning is a field of artificial intelligence. It refers to an area of computer science related to providing machines the ability to perform their own data analysis, decision making and forecasting. For example, one of the representative machine learning models is artificial neural network, which is a statistical learning algorithm inspired by the neural network structure of biology. In addition, there are other machine learning models such as decision tree model, naive bayes model and SVM(support vector machine) model. Among the machine learning models, we use SVM model in this study because it is mainly used for classification and regression analysis that fits well to our study. The core principle of SVM is to find a reasonable hyperplane that distinguishes different group in the data space. Given information about the data in any two groups, the SVM model judges to which group the new data belongs based on the hyperplane obtained from the given data set. Thus, the more the amount of meaningful data, the better the machine learning ability. In recent years, many financial experts have focused on machine learning, seeing the possibility of combining with machine learning and the financial field where vast amounts of financial data exist. Machine learning techniques have been proved to be powerful in describing the non-stationary and chaotic stock price dynamics. A lot of researches have been successfully conducted on forecasting of stock prices using machine learning algorithms. Recently, financial companies have begun to provide Robo-Advisor service, a compound word of Robot and Advisor, which can perform various financial tasks through advanced algorithms using rapidly changing huge amount of data. Robo-Adviser's main task is to advise the investors about the investor's personal investment propensity and to provide the service to manage the portfolio automatically. In this study, we propose a method of forecasting the Korean volatility index, VKOSPI, using the SVM model, which is one of the machine learning methods, and applying it to real option trading to increase the trading performance. VKOSPI is a measure of the future volatility of the KOSPI 200 index based on KOSPI 200 index option prices. VKOSPI is similar to the VIX index, which is based on S&P 500 option price in the United States. The Korea Exchange(KRX) calculates and announce the real-time VKOSPI index. VKOSPI is the same as the usual volatility and affects the option prices. The direction of VKOSPI and option prices show positive relation regardless of the option type (call and put options with various striking prices). If the volatility increases, all of the call and put option premium increases because the probability of the option's exercise possibility increases. The investor can know the rising value of the option price with respect to the volatility rising value in real time through Vega, a Black-Scholes's measurement index of an option's sensitivity to changes in the volatility. Therefore, accurate forecasting of VKOSPI movements is one of the important factors that can generate profit in option trading. In this study, we verified through real option data that the accurate forecast of VKOSPI is able to make a big profit in real option trading. To the best of our knowledge, there have been no studies on the idea of predicting the direction of VKOSPI based on machine learning and introducing the idea of applying it to actual option trading. In this study predicted daily VKOSPI changes through SVM model and then made intraday option strangle position, which gives profit as option prices reduce, only when VKOSPI is expected to decline during daytime. We analyzed the results and tested whether it is applicable to real option trading based on SVM's prediction. The results showed the prediction accuracy of VKOSPI was 57.83% on average, and the number of position entry times was 43.2 times, which is less than half of the benchmark (100 times). A small number of trading is an indicator of trading efficiency. In addition, the experiment proved that the trading performance was significantly higher than the benchmark.

• Journal of the Daesoon Academy of Sciences
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• v.43
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• pp.31-66
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• 2022

In Korea, the concept of publicness, although conceptually unclear, is being used as a medium between religious groups and other areas of society. In this situation, it is necessary to discuss the concept and agenda of publicness related to religions. For this purpose, we reviewed the relationship and agenda between publicness and faith, and then analyzed the cases of creating sacred objects and holy sites in connection with the concept of publicness. Specifically, according to Chapter II, Publicness and Faith, theologians and sociologists interested in publicness generally presuppose or aim for social participation and change. In this context, the agenda related to religious publicness can include the ground of non-Christian publicness, interreligious equality in the public spheres, the status of religious bodies, and the participation of researchers in the public spheres. In Chapter III, Sacred Objects and Publicness, we divided religious publicness into 'publicness within religion' and 'publicness outside of religion.' According to this classification, rituals are a key factor in creating publicness within religion. Publicness outside of religion is not intrinsic, but is constructed through various external debates. In Chapter IV, Sacred Holy Sites and Publicness, we reviewed cases of the construction of Catholic holy sites and analyzed oppositional logic provided by other religious groups in relation to the publicness outside of religion. Those cases internally created publicness within religion but lead to evaluation and debate about publicness outside of religion in public spheres in which various religions participate. Those who opposed the creation of Catholic holy sites used the logic that Catholicism was eliminating the heritage and values of other religions, and responded by expanding this to include the logic that the Catholics were weakening publicness or creating religious bias.

• (The) Research of the performance art and culture
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• no.19
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• pp.379-418
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• 2009

This study is a link in a chain which grope for the description of puppet performance history. This study imply my intention which is not a description of puppet performance 'history' but a description of 'puppet performance' history. Object materials of this study is materials connected with puppet performance from ancient times to Chosun dynasty. Object materials of this study include not only records but also remains and pictures. Discussion start with regulation of puppet performance materials and establishment of a classification criterion. As a result of that discussion, the age of puppet performance is as follows: 'the age of diverse use of puppet', 'the age of ritual puppet performance of worship', 'the age of play puppet performance of handling', 'the age of ritual puppet performance of display', 'the age of ritual puppet performance of expulsion', 'the age of ritual puppet performance of handling', 'the age of play puppet performance of display', 'the age of play puppet performance of handling and voice-acting'. According to the internal division of age, the description of puppet performance history which is spread chronologically is attempted. As a result of the description, I confirm that puppet performance reveal a one's unfolding process. And a distinct aspect from the general cultu! re history is found. The development process which is a changeover that is 'from ritual puppet performance to play puppet performance' is amended by a circulation of ritual puppet performance and play puppet performance'. And the development process which is a changeover 'from static puppet to dynamic puppet' is amended by a circulation of static puppet and dynamic puppet'. Like this the thing which is laid in the inside which is not a one sided changeover but is a circulation is said that from one age of puppet performance to other age of puppet performance is not a close of former puppet performance tradition. Unfolding from one age to other age, on the other hand former puppet performance reveal aspect which is a continuance and change with a one's vitality. And a relation of mutual influence is exist between the ritual puppet performance and the play puppet performance on a large scale, among the puppet performance types on a small scale. this also don't overlook in cas! e of a groping of puppet performance history.

• Journal of Preventive Medicine and Public Health
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• v.7 no.1
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• pp.1-28
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• 1974

The writers have conducted the investigation to assess the nutritional status of young rural Korean children aged from 0 to 4 years old in August 1971. The survey areas were Kaejong-myon. Daeya-myon, Okku-gun, Jeonra-bukdo, Korea. These survey areas were typical agricultural plain areas. The total numbers of children examined were 2,706 comprising 1,394 male and 1,312 female. The weight, height, and chest circumference of children were measured and means and standard deviations. were calculated for each measurement. In addition, the nutritional status of each child was classified by the four levels of malnutrition and the Gomez classification, The examination of red blood cell count, haematocrit value, and intestinal parasite infection were carried out at the same time. In general, recent work tend to suggest that environmental influences, especially nutrition, are of great importance than genetic background or other biological factors for physical growth and development. Certainly the physical dimensions of the body are much influenced by nutrition, particularly in the rapidly growing period of early childhood. Selected body measurements can therefore give valuable information concerning protein-calory malnutrition. Growth can also be affected by bacterial, viral, and parasitic infection. For the field workers in a developing country, therefore, nutritional anthropometry appears to be of greatest value in the assessment of growth failure and undernutrition, principally from lack of protein and calories. In order to compare and evaluate the data obtained, the optimal data of growth from the off-spring of the true well-fed, medically and socially protected are needed. So-called 'Standards' that have been compiled for preschool children in Korea, however, are based on measurement of children from middle or lower socio-economic groups, who are, in fact, usually undernourished from six months of age onwards and continuously exposed to a succession of infective and parasitic diseases. So that, the Harvard Standards which is one of the international reference standards was used as the reference standards in this study. Findings of the survey were as follows: A. Anthropometric data: 1) Comparing the mean values for body weight obtained with the Korean standard weight of the same age, the rural Korean children were slightly haevier than the Korean standard values in both sexes. Comparing with the Japanese children values, the rural Korean children were slightly haevier in male and in the infant period of female but lighter in female of the period of 1 to 4 years old than Japanese children. 2) Comparing the mean values for height obtained with the Korean standard height of the same age, the rural Korean children were taller than the Korean standard values except the second half of infatn period in both sexes. Comparing with the Japanese children, the rural Korean children were slightly smaller than Japanese children except the first half of infant peroid in both sexes. 3) Mear values of chest circumference of rural Korean children obtained were less than the Korean standard values of the same ages in both sexes. B. Prevalence of Protein-Calory Malnutrition: Children examined were devided into two groups, i. e., infant(up to the first birthday) and toddler (1 to 4 fears old). 1) Percentages of four levels of malnutrition: a) When the nutrtional status of each child was classified (1) by body weight value, the percentages for male and female of children attained standard growth were 52.8%(infant 83.3%, toddler 44.4%) and 39.7% (infant 74.5%. toddler 30.5%), the first level of malnutrition were 31.9%(infant 13.7%, toddler 36.9%) and 31.7%(infant 15.3%, toddler 36,0%), the second level of malnutrition were 12.3%(infant 1.7%, toddler 15.3%) and 23.3% (infant 7.7%, fodder 27.5%), the third level of malnutrition were 2.7%(infant 0.7%, toddler 3.2%) and 4.6%(infant 1.8%, toddler 5.3%) the fourth level of malnutrition were 0.3% (infant 0.7%, toddler 0.2%) and 0.7% (0.7% for infant and toddler) respectively. (2) by height value, the percentages for male and female of children attained standard growth were 80.3% (infant 97.3%, toddler 75.6%) and 75.1% (infant 96.4%, toddler 69.5), the first level of malnutrition were 17.9% (infant 2.0%, toddler 22.3%) and 23.6% (infants 3.6%, toddler 28.8%), the second level of malnutrition were 1.2% (infant 0.3%, toddler 1.5%) and 1.1% (infant 0%, toddler 1.4%), the third level of malnutrition were 0.4%(infant 0.3%, toddler 0.5%) and 0.2%(infant 0%, toddler 0.3%), the fourth level of malnutrition were 0.1%(infant 0%, toddler 0.1%) and 0% respectively. (3) by body weight in relation to height, the percentages for male and female of children attained standard growth were 87.9% (infant 77.6%, toddler 87.9%) and 78.2% (infant 77.4%, toddler 78.2%), the first level of malnutrition were 12.2% (infant 18.4%, toddler 10.6%) and 18.2% (infant 17.9%, toddler 18.3%), the second level of malnutrition were 1.9%(infant 3.3%, toddler 1.5%) and 3.0%(infant 3.3%, toddler 2.9%), the third level of malnutrition were 0.1%(infant 0%. toddler 0.1%) and 0.5% (infant 0%, toddler 0.6%), the fourth level of malnutrition were 0.1%(infant 0.7%, toddler 0%) and 0.3% (infant 1.5%, toddler 0%) respectively. b) When the nutritional status of each child according to the mother's age at perturition, i. e., young aged mother (up to 30 years old), middle aged mother (31 to 40 years old) and old aged mother (41 years or above) was classified (1) by body weight, among infants and toddlers, at each year of age, with increasing the mother's age, there was an increase in percentage of subjects underweight. This tendency of increasing percentage of underweight was more significant in the infant period than the toddler period. (2) by height value, no significant differences between each mother's age group were found. c) When the nutritional status of each child according to the birth rank, i. e., lower birth rank (first to third) and higher birth rank (fourth or above) was classified (1) by weight value, children of higher birth rank were slightly more often underweight than those of lower birth rank, but not significant. (2) by height value, no differences were found between children of lower and higher birth rank. 2) Gomez Classification: When the nutritional status of each child was classified a) by body weight value, the percentages for male and female of children. attained standard growth were 53.1% (infant 82.6%, toddler 44.9%) and 39.2% (infant 73.4%, toddler 30.1%), the first degree of malnutrition were 39.4% (infant 14.7%, toddler 46.2%) and 47.1% (infant 21.9%, toddler 53.8%), the second degree of malnutrition were 7.3%(infant 2.3%, toddler 8.6%) and 12.9% (infant 4.0%, toddler 15.2%). and the third degree of malnutrition were 0.2%. (infant 0.3%, toddler 0.2%) and 0.8% (infant 0.7%, toddler 0.9%) respectively. b) by height value, the percentages for male and female of children attained standard growth were 80.8% (infant 97.0%, toddler 76.3%) and 73.8%(infant 95.6%, toddler 68.0%), the first degree of malnutrition were 18.5% (infant 2.7%, toddler 22.9%) and 24.6% (infant 4.4%, toddler 30.0%), the second degree of malnutrition were 0.6%(infant 0.3%, toddler 0.7%) and 0.5% (infant 0.1%, toddler 0.7%), and the third degree of malnutrition were 0.1%(infant 0%, toddler 0.1%) and 1.1% (infant 0%, toddler 1.3%) respectively. C. Results of clinical laboratory examination: 1) Red blood cells: The ranges of mean red blood cell counts for male and female were $3,538,000/mm^3\;to\;4,403,000/mm^3\;and\;3,576,000/mm^3\;to\;4,483,000/mm^3$ respectively. The lowest red cell counts were seen at the age of 0-3 months for male and 1-2 months for female. 2) Haematocrit value : The ranges of haematocrit value of male and female were 35.1% to 38.8% and 34.7% to 38.8% respectively. The lowest haematocrit values were seen at the age of 2-3 months for male and 1-2, months for female. 3) The prevalence rates of intestinal parasites for male and female children with Ascaris lumbricoides were 34.1% (infant 18.8%, toddler 38.1%) and 36.0%(infant 18.4%, toddler 40.7%), with Trichocephalus trichiuris were 6.8% (infant 2.9%, toddler 7.9%) and 9.0% (infant 3.0%, toddler 10.6%), with Hookworm were 0.3% (infant 0.5%, toddler 0.2%) and 0.3% (infant 0.5%, toddler 0.3%), with Clonorchis sinensis were 0.4%(infant 0%, toddler 0.5%) and 0.1%(infant 0%, toddler 0.1%) respectively.

• Journal of Intelligence and Information Systems
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• v.18 no.4
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• pp.117-127
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• 2012

Due to the recent expansion of the Web 2.0 -based services, along with the widespread of smartphones, online social network services are being popularized among users. Online social network services are the online community services which enable users to communicate each other, share information and expand human relationships. In the social network services, each relation between users is represented by a graph consisting of nodes and links. As the users of online social network services are increasing rapidly, the SNS are actively utilized in enterprise marketing, analysis of social phenomenon and so on. Social Network Analysis (SNA) is the systematic way to analyze social relationships among the members of the social network using the network theory. In general social network theory consists of nodes and arcs, and it is often depicted in a social network diagram. In a social network diagram, nodes represent individual actors within the network and arcs represent relationships between the nodes. With SNA, we can measure relationships among the people such as degree of intimacy, intensity of connection and classification of the groups. Ever since Social Networking Services (SNS) have drawn increasing attention from millions of users, numerous researches have made to analyze their user relationships and messages. There are typical representative SNA methods: degree centrality, betweenness centrality and closeness centrality. In the degree of centrality analysis, the shortest path between nodes is not considered. However, it is used as a crucial factor in betweenness centrality, closeness centrality and other SNA methods. In previous researches in SNA, the computation time was not too expensive since the size of social network was small. Unfortunately, most SNA methods require significant time to process relevant data, and it makes difficult to apply the ever increasing SNS data in social network studies. For instance, if the number of nodes in online social network is n, the maximum number of link in social network is n(n-1)/2. It means that it is too expensive to analyze the social network, for example, if the number of nodes is 10,000 the number of links is 49,995,000. Therefore, we propose a heuristic-based method for finding the shortest path among users in the SNS user graph. Through the shortest path finding method, we will show how efficient our proposed approach may be by conducting betweenness centrality analysis and closeness centrality analysis, both of which are widely used in social network studies. Moreover, we devised an enhanced method with addition of best-first-search method and preprocessing step for the reduction of computation time and rapid search of the shortest paths in a huge size of online social network. Best-first-search method finds the shortest path heuristically, which generalizes human experiences. As large number of links is shared by only a few nodes in online social networks, most nods have relatively few connections. As a result, a node with multiple connections functions as a hub node. When searching for a particular node, looking for users with numerous links instead of searching all users indiscriminately has a better chance of finding the desired node more quickly. In this paper, we employ the degree of user node vn as heuristic evaluation function in a graph G = (N, E), where N is a set of vertices, and E is a set of links between two different nodes. As the heuristic evaluation function is used, the worst case could happen when the target node is situated in the bottom of skewed tree. In order to remove such a target node, the preprocessing step is conducted. Next, we find the shortest path between two nodes in social network efficiently and then analyze the social network. For the verification of the proposed method, we crawled 160,000 people from online and then constructed social network. Then we compared with previous methods, which are best-first-search and breath-first-search, in time for searching and analyzing. The suggested method takes 240 seconds to search nodes where breath-first-search based method takes 1,781 seconds (7.4 times faster). Moreover, for social network analysis, the suggested method is 6.8 times and 1.8 times faster than betweenness centrality analysis and closeness centrality analysis, respectively. The proposed method in this paper shows the possibility to analyze a large size of social network with the better performance in time. As a result, our method would improve the efficiency of social network analysis, making it particularly useful in studying social trends or phenomena.