• Asia pacific journal of information systems
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• v.20 no.1
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• pp.127-140
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• 2010

The benefit that a consumer derives from the use of a good often depends on the number of other consumers purchasing the same goods or other compatible items. This property, which is known as network externality, is significant in many IT related industries. Over the past few decades, network externalities have been recognized in the context of physical networks such as the telephone and railroad industries. Today, as many products are provided as a form of system that consists of compatible components, the appreciation of network externality is becoming increasingly important. Network externalities have been extensively studied among economists who have been seeking to explain new phenomena resulting from rapid advancements in ICT (Information and Communication Technology). As a result of these efforts, a new body of theories for 'New Economy' has been proposed. The theoretical bottom-line argument of such theories is that technologies subject to network effects exhibit multiple equilibriums and will finally lock into a monopoly with one standard cornering the entire market. They emphasize that such "tippiness" is a typical characteristic in such networked markets, describing that multiple incompatible technologies rarely coexist and that the switch to a single, leading standard occurs suddenly. Moreover, it is argued that this standardization process is path dependent, and the ultimate outcome is unpredictable. With incomplete information about other actors' preferences, there can be excess inertia, as consumers only moderately favor the change, and hence are themselves insufficiently motivated to start the bandwagon rolling, but would get on it once it did start to roll. This startup problem can prevent the adoption of any standard at all, even if it is preferred by everyone. Conversely, excess momentum is another possible outcome, for example, if a sponsoring firm uses low prices during early periods of diffusion. The aim of this paper is to analyze the dynamics of the adoption process in markets exhibiting network effects by focusing on two factors; switching and agent heterogeneity. Switching is an important factor that should be considered in analyzing the adoption process. An agent's switching invokes switching by other adopters, which brings about a positive feedback process that can significantly complicate the adoption process. Agent heterogeneity also plays a important role in shaping the early development of the adoption process, which has a significant impact on the later development of the process. The effects of these two factors are analyzed by developing an agent-based simulation model. ABM is a computer-based simulation methodology that can offer many advantages over traditional analytical approaches. The model is designed such that agents have diverse preferences regarding technology and are allowed to switch their previous choice. The simulation results showed that the adoption processes in a market exhibiting networks effects are significantly affected by the distribution of agents and the occurrence of switching. In particular, it is found that both weak heterogeneity and strong network effects cause agents to start to switch early and this plays a role of expediting the emergence of 'lock-in.' When network effects are strong, agents are easily affected by changes in early market shares. This causes agents to switch earlier and in turn speeds up the market's tipping. The same effect is found in the case of highly homogeneous agents. When agents are highly homogeneous, the market starts to tip toward one technology rapidly, and its choice is not always consistent with the populations' initial inclination. Increased volatility and faster lock-in increase the possibility that the market will reach an unexpected outcome. The primary contribution of this study is the elucidation of the role of parameters characterizing the market in the development of the lock-in process, and identification of conditions where such unexpected outcomes happen.

• Korea journal of population studies
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• v.11 no.1
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• pp.204-229
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• 1988

This paper documents and discusses trends and differentials in youth's participation in the labor force and employment. Youth in this study is defined asthe young aged 15-29. Youth passes through a series of life-course transitions,which include school completion own family formation(marriage and childbirth) .mandatory service in the army (by males) , and their economic activities are affectedby those life-course events. Accordingly we show how and to what extent youth'slabor force participation and employment varies with age and how the age patternhas changed over time.Throughout the 1980's and 1990's, youth's labor force participation showeddifferent trends by age group Labor fDrce participation rate of the 15-19 agedsteeply decreased, while that of the 25-29 steadily increased during the twodecades, the rate fsr the 20-24 aged showing not much variation. The former is dueto the increased rate of school enrollment among the age group, while the lattercould be attributed, in part, to the young women s increased and more steadyparticipation in the labor force over time.While labor force participation could be considered as a result of one's choicesand preferences, employment opportunities are more or less restricted by labormarket structure and institutions . This study documents how the structuralconstraints have interacted with individual and group attributes to differentiateemployment opportunities between individuals (educational background) and groups(especially sex diffrences) . One of the most salient feature of youth's em[ploymentstructure is the recent high unemployment rate of the college graduates. We discusshow that is related to the'credential society'in which one's educational credentials and it's social status play major role in determining who gets what in terms of job opportunities. Also is discussed the discordance between school and labor marketsupply and demand system, which is apparent in the prolonged oversupply of thecollege graduates, which is due to the consistently high rate of college entranceobserved since the early 1980's. Theoretically the job market for college graduates isviewed not as the'neoclassical'wage competition market but as job competition market in which one's (good) job opportunity is determined by one s position in thejob queue, which is in turn heavily dependent on from which college one get shis/her college degree as well as one's sex.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.363-371
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• 2023

To construct a ship, blocks of various sizes must be moved and erected . In this process, lugs are used such that they match the block fastening method and various functions suitable for the characteristics of each shipyard facility. The sizes and shapes of the lugs vary depending on the weight and shape of the block structures. The structure is reinforced by welding the doubling pads to compensate for insufficient rigidity around the holes where the shackle is fastened. As for the method of designing lugs according to lifting loading conditions, a simple calculation based on the beam theory and structural analysis using numerical modeling are performed. In the case of the analytical method, a standardized evaluation method must be established because results may differ depending on the type of element and modeling method. The application of this ambiguous methodology may cause serious safety problems during the process of moving and turning-over blocks. In this study , the effects of various parameters are compared and analyzed through numerical structural analysis to determine the modeling conditions and evaluation method that can evaluate the actual structural response of the lug. The modeling technique that represents the plate part and weld bead around the lug hole provides the most realistic behavior results. The modeling results with the same conditions as those of the actual lug where only the weld bead is connected to the main body of the lug, showed a lower ulimated strength compared with the results obtained by applying the MPC load. The two-dimensional shell element is applied to reduce the modeling and analysis time, and a safety working load was verified to be predicted by reducing the thickness of the doubling pad by 85%. The results of the effects of various parameters reviewed in the study are expected to be used as good reference data for the lug design and safe working load prediction.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1413-1425
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• 2023

The increasing frequency of wildfires due to climate change is causing extreme loss of life and property. They cause loss of vegetation and affect ecosystem changes depending on their intensity and occurrence. Ecosystem changes, in turn, affect wildfire occurrence, causing secondary damage. Thus, accurate estimation of the areas affected by wildfires is fundamental. Satellite remote sensing is used for forest fire detection because it can rapidly acquire topographic and meteorological information about the affected area after forest fires. In addition, deep learning algorithms such as convolutional neural networks (CNN) and transformer models show high performance for more accurate monitoring of fire-burnt regions. To date, the application of deep learning models has been limited, and there is a scarcity of reports providing quantitative performance evaluations for practical field utilization. Hence, this study emphasizes a comparative analysis, exploring performance enhancements achieved through both model selection and data design. This study examined deep learning models for detecting wildfire-damaged areas using Landsat 8 satellite images in California. Also, we conducted a comprehensive comparison and analysis of the detection performance of multiple models, such as U-Net and High-Resolution Network-Object Contextual Representation (HRNet-OCR). Wildfire-related spectral indices such as normalized difference vegetation index (NDVI) and normalized burn ratio (NBR) were used as input channels for the deep learning models to reflect the degree of vegetation cover and surface moisture content. As a result, the mean intersection over union (mIoU) was 0.831 for U-Net and 0.848 for HRNet-OCR, showing high segmentation performance. The inclusion of spectral indices alongside the base wavelength bands resulted in increased metric values for all combinations, affirming that the augmentation of input data with spectral indices contributes to the refinement of pixels. This study can be applied to other satellite images to build a recovery strategy for fire-burnt areas.

• Korean Journal of Heritage: History & Science
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• v.45 no.3
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• pp.60-79
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• 2012

Environment of ancient Chinese Buddhist temple can be classified to three types such as regional society(鄕村), famous mountain(名山), and urban areas(都市). This made differences in environment where a temple existed and in turn, affected development of Buddhism. And this made another type in relationship between Buddhist temple and a society. This study explains influences which regional society gave on not only Buddhist temple and a monk but also existence and development of Buddhism. When temples are placed in different environmental position, that is, urban areas and regional society, among a social structure, they eventually should adapt to a different society externally and internally. As told in above, ancient Chinese Buddhist temple was located in regional society, famous mountain, and urban areas. Since Eastern Jin and Sixteen Kingdoms, as number of temple much increased, and temples and monks were concentrated on famous mountain, temples in famous mountains and urban areas had developed showing similar aspects each other. But because temples in regional society were influenced a little differently, this study focused on the point. There are four kinds of influences between temples and monks in regional areas. Monks in regional areas had a comparatively close relationship with a society because they came from same area or surrounding areas. Therefore,powers of regional areas restrict influences made by monk group in temple. Second, temples in regional areas shared their joys and sorrows depending on regional economy. Temples in regional areas became a public place for the society and often a market place. In fact, construction and existence of a temple originally became a driving force in regional economy. This is because construction of temple needs artisans and materials and some temples had visitors and included market economy like consumption of incense and candles, though the economic size was large or small. And when regional areas experienced natural disaster or man-made disaster or had poor harvest or economy was in depression, monks left temples and then, temples themselves could not exist. Third, the relationship between temples in regional areas and Buddhists was distinguished from the temples in urban areas and famous mountains. This is because temples in China were places where monks practiced and at the same time, places where general Buddhists worshipped. So there were always a number of Buddhists around the temples. Forth, Buddhism in resional areas was connected to regional Folk beliefs. As a result, Buddhism was spread across the nation, worship with local color often was changed to Buddhist belief or was tinged with Buddhism. While temples in regional areas maintained a close relationship with regional society.they were influenced by the region or gave influences. As a representative example, temples in regional areas showed model behaviors instead of roles of facilities related to various cultures with comparatively advanced level - for example, school, hospital etc. The temples highly affected funerary rites in regional areas. Chinese tombs were mainlymade in regional areas. After death,people living in urban areas were buried in hometown or at least, they were buried in suburbs not urban areas. Temples in regional areas generally participated in funerary rites. Above shows that though most of famous Buddhist temples were located in urban areas not in famous mountains,majority of temples were located in vast regional areas. Through mutual interaction between temples and regional society, the temples in the regional areas were related to Chinese people of over 90% and regional areas became the most important foundation for Buddhism in China. Mutual influences between temples in regional areas and the general public in regions were omnidirectional and spreaded to every aspects of social life in small or large degree. Thus Tombs in temple were widely spreaded across regional areas over time and space. This is enough to explain a close relationship between Buddhist temples and rural society in ancient China.

• Journal of dental hygiene science
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• v.11 no.3
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• pp.285-292
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• 2011

The purpose of this study was to analyze and investigate temporomandibular disorders(TMD) and dental clinic outpatients by food intake ability to improve the quality of life. A survey of questionnaires with 208 subjects visiting a dental clinics located in Daejeon city from January to September in 2010 was performed. Analysis were performed with survey results, in which a symptoms of TMD, parafunctional habits and abnormal functions, food intake ability : 1. The main symptoms of TMD showed pain on TMJ(45.7%), pain on joint sound(45.2%), pain during chewing(41.3%), pain during mouth opening(38.0%), pain during non chewing(19.7%) and pain on joint dislocation(13.0%) in turn. 2. The symptoms of TMD by gender showed joint dislocation of 18.0% for male and 8.3% for female(p=0.038); pain on chewing of 49.0% for male and 34.3% for female(p=0.031), which were statistically significant. 3. The parafunctional habits and abnormal functions by gender showed clenching habit of 35.0% for male and 22.0% for female; bruxism of 21.0% for male and 9.3% for female, which were statistically significant. 4. The symptoms of TMD by age showed 52.8% of 27.8% for often and 25.0% for sometimes of 21-30 age in pain on TMJ, which were statistically significant(p=0.001). 5. The parafunctional habits and abnormal functions by age showed over 31 age of 48.3%, which were statistically significant(p=0.003). 6. The food intake ability by symptoms of TMD showed no joint sound(p=0.000), no pain on chewing(p=0.000) and without pain on TMJ(p=0.000), which were statistically significant. 7. The food intake ability by parafunctional habits and abnormal functions showed no clenching habit(p=0.000), no bruxism(p=0.000) and no headache, which were statistically significant. 8. The distribution type of operation by symptoms of TMD showed 30.8% of rest, 24.0% of physical medicine and 16.4% of pharmacotherapy. The pain on chewing showed 36.0% of pharmacotherapy; 52.4% of pain on TMJ for often and 40.5% for sometimes, in which pharmacotherapy and physical medicine were statistically significant(p=0.000). These results showed that management run parallel with survey for multiple factors in TMD we consider aspect of physical, social, physiology to enhance quality of life to increase food intake, construction of program for treatment and prevention because the individual differences need to be multifaceted, further research is suggested to continue.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.263-268
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• 2009

The Yellow Sea is extremely important to the economy and to the health and well-being of surrounding countries, Korea and China. Recently, the Yellow Sea is under constantly increasing threat of degradation due to the increase of environmental pollution and over-fishing. The governments of Korea and China have been aware of the importance of the Yellow Sea and reached an Environmental Agreement between Korea and China at the governmental level(November, 1993) According to this environmental agreement the Yellow Sea Environmental Cooperative Research between Korea and China has been undertaken since 1997. The joint cruise had been conducted once a year at 33 stations in the 4 lines of the Yellow Sea where the 9 stations of the D line was newly added in the 7th cruise in 2003. The samples were analyzed by scientists of both countries at the WSFRI, Korea and the OEMNC of the SEPA, China in turn, the annual report has been published every year during 1998-2008. The scientific efforts to fix the cruise time in October and to extend research frequency, as twice a year, should be considered, and this requires the governmental supports such as research funds and other related administrational assistance on both sides. Finally, scientists should also pay a concentrated attention to standardize the analytical methods including quality control and to improve this Yellow Sea research as one of the most representative international projects in the Yellow Sea where sharing additional informations available, if exist of dumping sites and material content, and of the freshwater quality will be of great help to broaden the output of this joint research project.

• Research in Community and Public Health Nursing
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• v.10 no.1
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• pp.70-79
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• 1999

This study attempts to encourage the development of a rehabilitation delivery system as a substitute service for hospitalization such as a community based intermediate facility or home health care. We need substitute services for hospitalization to curtail the length of stay for inpatients due to car accidents. It focused on developing an estimation for early discharge based on a detailed statement of treatment from medical records of 109 inpatients who were hospitalized at General Hospital in 1997. This study has three specific purposes: First, to find the mean length of stay and mean medical expenditure. Second, to estimate the mean of early discharge from the mean length of stay. Third, to analyize the income effect per bed from early discharge. In order to analyze the length of stay and medical expenditure of inpatients the author conducted a micro and macro-analysis with medical expenditure records. To estimate the early discharge we examined with a group of 4 experts decreases in the amount of treatment after surgery, in treatments, in tests, in drug methods. We also looked their vital signs, the start of ROM exercise, the time removel, a patient's visitations, and possible stable conditions. In addition to identifing the income effect due to an early discharge, the data was analyzed by an SPSS-PC for windows and Excell program with a regression analysis model. The research findings are as follows: First, the mean length of stay was 47.56 days, but the mean length of stay due to early discharge was 32.26 days. The estimation of early discharge days was shown to depend on the length of stay. The longer the length of stay, the longer the length before discharge. For example, if the patient stayed under 14 days the mean length of stay was 7.09 while an early discharge was 6.39, whereas if the mean length of stay was 155.73, the early discharge time was 107.43. The mean medical expenditure per day of car accident patients was found to be 169,085 Won, whereas the mean medical expenditure per day was shown to be in a negative linear form according to the length of stay. That is the mean expenditure for under 14 days of stay was 303,015 Won and the period of the hospitalization of 15 days to 29 days was 170,338 Won and those of 30 days to 59 days was 113,333 Won. The estimation of the income effect due to being discharged 16 days was around 2,350,000 Won with a regression analysis model. However, this does not show the real benefits from an early discharge, but only the income increasing amount without considering prime medical cost at a general hospital. Therefore, we need further analysis on cost containments and benefits incending turn over rates and medical prime costs. From these research findings, the following suggestions have been drawn, we need to develop strategies on a rehabilitation delivery system focused on consumers for the 21st century. Varions intermediate facilities and home health care should be developed in the community as a substitute for shortening the length of stay in hospitals. In home health care cases, patients who want rehabilitation services as a substitute for hospitalization in cooperation with private health insurance companies might be available immediately.

• Journal of Embryo Transfer
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• v.26 no.1
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• pp.65-70
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• 2011

This study was conducted to investigate the survival rate of AndroMed and Tris-egg yolk extender for cryopreservation of Korean Native Bull Semen (Chick Cow). Semen was collected from a Korean Native Bull Semen over 3 year's old. The semen was diluted 1:1 by AndroMed and Tris-egg yolk extender. The pellet was diluted to final sperm concentration of $5{\times}10^7$ cell/ml by doubling in every 10 minutes at $4^{\circ}C$ cold chamber. The semen was equilibrated for 1 hrs at cold chamber and packed to 0.5 ml straw. The semen straws were located above 5 cm of liquid nitrogen for 5 minutes. And then the frozen straw was plunged to LN2. The presented straws were examined the viability and motility after thawed at $37^{\circ}C$ water bath. The survival rates was significantly higher (p<0.05) in Tris-egg yolk extender than AndroMed extender ($89.7{\pm}19.8$ vs. $73.4{\pm}11.2$). However, motility was no significant differences ($78.4{\pm}18.7$ vs. $67.9{\pm}14.6$). Survival rate in time of equilibration between visual and CASA program had higher in 2 h ($86.33{\pm}9.4$ vs. $92.32{\pm}12.4$) than in 5 h ($78.20{\pm}7.8$ vs. $88.28{\pm}13.1$) 15 h ($65.24{\pm}6.6$ vs. $76.48{\pm}17.3$) 20 h ($56.26{\pm}4.6$ vs. $67.73{\pm}18.4$). The development rates to cleavage was higher in Tris-egg yolk extender than AndroMed extender (82.2% vs. 81.7%). Similarly, the development rates to blastocyst was significantly higher (p<0.05) in Tris-egg yolk extender than AndroMed extender (42.3% vs. 29.6%). In conclusion, the obvious impact of this study will be its practical application to improve viability and fertilizing ability of cryopreserved spermatozoa used for in vitro fertilization (IVF) and AI, Which in turn will be beneficial to animal genetic resources conservation.

• Korean Journal of Medicinal Crop Science
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• v.12 no.4
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• pp.328-341
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• 2004

Presowing seed treatments used to enhance the rates of germination and afterward seedling emergence have not occasionally shown the same rate in indoor and field. The treatments considering germination mechanism and factors affecting germination must be totally included in indoor experiments so that the results drawn can be reproduced in the field. Seed germination is controlled by Phytochrome-mediated action changed with composition rates of red and far-red lights. Sunlight can penetrate soil into $6{\sim}9\;mm$ depth, which in turn means that seeds having $2{\sim}3\;mm$ in their width may receive the light if soil was covered 3 times over them. The penetrating light, moreover, turns to more far-red light than red light reverse to the sunlight. For germination tests after the artificial presowing seed treatments, therefore, seeds of smaller than 2 mm (< 2 mm), $2{\sim}3\;mm$, and larger than 3 mm (> 3 mm) must be done with incandescent lamp (IL) having more far-red light, with IL or in darkness, and in darkness, respectively. The 96 papers published in 13 Korean scientific journals up to the end of 2003 were analysed on the basis of the above explanation. 91 species were used 147 times as experimental materials; 101 times for < 2 mm seeds, 24 times for $2{\sim}3\;mm$ seeds and 22 times for > 3 mm seeds. If they were analysed as the light sources used for germination tests, correct applications reached more and less than 60% in both $2{\sim}3\;mm$ and > 3 mm seeds but 23% in < 2 mm seeds, conclusionally meaning that when the experimental results in the scientific papers were applied into farming practices, care was taken of their application because most of medicinal plant seeds were very small.