• The Journal of Advanced Prosthodontics
• /
• v.11 no.4
• /
• pp.202-208
• /
• 2019

PURPOSE. Fabrication of zirconia restorations with ideal mechanical properties in a short period is a great challenge for clinicians. The purpose of the study was to investigate the effect of heating rate on the mechanical and microstructural properties of monolithic zirconia. MATERIALS AND METHODS. Forty monolithic zirconia specimens were prepared from presintered monolithic zirconia blanks. All specimens were then assigned to 4 groups according to heating rate as Control, Group $15^{\circ}C$, Group $20^{\circ}C$, and Group $40^{\circ}C$. All groups were sintered according to heating rates with the sintering temperature of $1500^{\circ}C$, a holding time of 90 minutes and natural cooling. The phase composition was examined by XRD analysis, three-point bending test was conducted to examine the flexural strength, and Weibull analysis was conducted to determine weibull modulus and characteristic strength. Average grain sizes were determined by SEM analysis. One-way ANOVA test was performed at a significance level of 0.05. RESULTS. Only tetragonal phase characteristic peaks were determined on the surface of analyzed specimens. Differences among the average grain sizes of the groups were not statistically significant. The results of the three-point bending test revealed no significant differences among the flexural strength of the groups (P>.05). Weibull modulus of groups was ranging from 3.50 to 4.74. The highest and the lowest characteristic strength values were obtained in Group $20^{\circ}C$ and Control Group, respectively. CONCLUSION. Heating rate has no significant effect on the flexural strength of monolithic zirconia. Monolithic zirconia restorations can be produced in shorter sintering periods without affecting the flexural strength by modifying the heating rate.

• The Journal of the Acoustical Society of Korea
• /
• v.42 no.6
• /
• pp.511-518
• /
• 2023

Accurate ranging is one of the key factors in the test and evaluation process of underwater vehicles. In particular, when estimating range using Time of Arrival (ToA) values, signals such as Linear Frequency Modulation (LFM), a chirp signal, are highly applicable due to their correlated nature. However, in a Doppler shift environment with mobility, measurement errors may occur due to the range-Doppler coupling effect. In this paper, we propose a signal that compensates for the distance-Doppler coupling effect to reduce the measurement error of the arrival time value. The proposed signal is constructed by superimposing two types of LFM signals, and the range-Doppler coupling effect can be minimized. Through simulations, it is confirmed that the proposed signal is a way to compensate for the distance-Doppler coupling effect in the distance estimation of underwater mobile bodies, reducing the measurement error of the arrival time value.

• Journal of agriculture & life science
• /
• v.50 no.3
• /
• pp.1-11
• /
• 2016

With increasing interest, there have been studies on LiDAR(Light Detection And Ranging)-based DEM(Digital Elevation Model) to acquire three dimensional topographic information. For producing LiDAR DEM with better accuracy, Filtering process is crucial, where only surface reflected LiDAR points are left to construct DEM while non-surface reflected LiDAR points need to be removed from the raw LiDAR data. In particular, the changes of input values for filtering algorithm-constructing parameters are supposed to produce different products. Therefore, this study is aimed to contribute to better understanding the effects of the changes of the levels of GroundFilter Algrothm's Mean parameter(GFmn) embedded in FUSION software on the accuracy of the LiDAR DEM products, using LiDAR data collected for Hwacheon, Yangju, Gyeongsan and Jangheung watershed experimental area. The effect of GFmn level changes on the products' accuracy is estimated by measuring and comparing the residuals between the elevations at the same locations of a field and different GFmn level-produced LiDAR DEM sample points. In order to test whether there are any differences among the five GFmn levels; 1, 3, 5, 7 and 9, One-way ANOVA is conducted. In result of One-way ANOVA test, it is found that the change in GFmn level significantly affects the accuracy (F-value: 4.915, p<0.01). After finding significance of the GFmn level effect, Tukey HSD test is also conducted as a Post hoc test for grouping levels by the significant differences. In result, GFmn levels are divided into two subsets ('7, 5, 9, 3' vs. '1'). From the observation of the residuals of each individual level, it is possible to say that LiDAR DEM is generated most accurately when GFmn is given as 7. Through this study, the most desirable parameter value can be suggested to produce filtered LiDAR DEM data which can provide the most accurate elevation information.

• Journal of Food Hygiene and Safety
• /
• v.27 no.1
• /
• pp.74-80
• /
• 2012

Fish contain both the neurotoxin methyl mercury (MeHg) and nutrients important for brain development. The developing brain appears to be most sensitive to MeHg toxicity and mothers who consume fish during pregnancy expose their fetus prenatally. Although brain development is most dramatic during fetal life, it continues for years postnatally and additional exposure can occur when a mother breast feeds or the child consumes fish. This raises the possibility that MeHg might influence brain. We evaluated the relationship between fish consumption and mercury exposure levels in umbilical cord blood of the pregnant women of the city of Tongyeong city, Korea. A total of 159 pregnant women residing in the city of Tongyeong, Korea were recruited for the study between October 2010 and March 2011. Fish consumption was evaluated using food frequency questionnaires including detailed questions on fish consumption. We used ANOVA to estimated the particular relevance between the frequency of fish consumption and the umbilical cord blood mercury concentration, and other various factors. The average mean concentration of mercury levels in umbilical cord blood of pregnant women who participated in our study were $2.69{\pm}2.50ppb$, ranging from 0.01 to 14.80 ppb. The mean concentration of umbilical cord blood mercury exposure was lower than the level recommended by WHO (5.0 ppb), but the mercury exposure level exceeded the WHO recommended in 17 (10.7%) cases of umbilical cord blood. Mercury levels in cord blood of pregnant women were $2.04{\pm}2.00ppb$, ranging from 0 to 8.00 ppb in below 29 years old and $3.18{\pm}2.74ppb$, ranging from 0.01 to 14.80 ppb in more 30 years old. In this study, there was a significant difference for the frequency of eating fish between the groups (p < 0.01). The level of the groups that ate fish 3 to more times per week ($4.15{\pm}4.02ppb$) was significant higher as compared with the level of other groups that ate fish 1 to times per week ($2.63{\pm}2.22ppb$) and none per week ($1.06{\pm}1.44ppb$), respectively. We found that the mercury concentration of umbilical cord blood associate with fish consumption and this was statistically significant and this fact revels that fish consumption is positively related to mercury levels in the umbilical cord blood. We need systematic and periodic research on the general population to prevent mercury poisoning, which can be cause by low-level mercury exposure from dietary intake such as chronic fish consumption.

• Journal of Music and Human Behavior
• /
• v.2 no.1
• /
• pp.67-85
• /
• 2005

The purpose of this study was to investigate the effect of music listening, autogenic training, and music-assisted autogenic training on the quality of life, physiological and psychological relaxation responses, and daily living in a population of migraine patients. Forty migraine patients, ranging 20 to 60 years, were referred to the researcher by their physicians and participated in the study. A convenience control-group pretest-posttest design was employed. The participants were randomly assigned to one of four groups: music listening (ML), autogenic training (AT), music-assisted autogenic training (MAT), or a control group participants, with n = 10 participants per group. The participants in experimental groups received four 30-minute sessions with an assigned treatment, once a week during a 4-week experiment period. The participants in the control group continued their regular medical treatment as prescribed by the doctor without receiving any other relaxation treatment. However, they were still aware of the research and their responsibilities for the study. The Migraine Assessment (MIDAS) and Migraine-Specific Quality of Life (MSQOL) questionnaire were used to investigate a migraine patients' quality of life collected before and after the 4-week experiment for all subjects. The physiological and psychological relaxation responses of migraine patients were measured by relaxation levels and forehead temperature recorded before and after each treatment session for the participants in three treatment conditions. The effect of the relaxation treatments on daily living of migraine patients was examined through the frequency and intensity of migraine headaches, and the amount of medication taken for migraine headaches during the 4-week experiment as recorded in participants' diary for all participants. The results found significant differences from pre- to posttest on the MIDAS, MSQOL, and relaxation levels while no significant was found among the groups. The analysis of forehead temperature showed no significant difference from pre- to posttest and among the groups. A one-way ANOVA was performed on the frequency, intensity, and amount of medication taken for migraine headaches during the 4-week experiment period. While results yielded no significant difference among the groups, the data indicate that the participants in the three treatment groups reported fewer migraine headaches, lower degrees of headache intensity, and less medication taken for migraine headaches than participants in the control group. A conclusion drawn from this study is that music listening itself as a relaxation treatment, or as an adjunct to other relaxation techniques can be effective in the treatment of migraine headaches.

• The Journal of Fisheries Business Administration
• /
• v.14 no.2
• /
• pp.15-68
• /
• 1983

From the economic point of view the fishing port is the complex of installations on land, organized to serve the fishing fleet and its cargo, and is the main link in the production chain of all components of the fishing industry, with the aim of achieving the planned targets with the minimum cost. Fishing port investment decisions have had significant impact on the development aims of Korean fisheries. Fishing port investments in Korea are made mostly by public or semipublic port authorities. Such investments should be judged not purely on the basis of financial profitability but rather on the extent to which they serve the development aims of the fishing industry. This makes the economic appraisal process more complex and presents certain problems in correctly quantifying the economic costs and benefits of the fishing port projects. This study concentrates more on the theoretical economic appraisal models than on the purely financial aspects of fishing port investments and points out the difference between the two approaches. In the result, there is clearly an element of judgment as to whether or not a shadow price needs to be used in estimating economic benefits and costs. From this viewpoint, some attempts are made to provide definitions of the possible economic benefits and costs, and methods for estimating and evaluating them in Part III and IV. Especially queueing theory is applied in the calculation of economic benefits. When a project is contemplated and analysis shows it to Lave a positive NPV, one question that arises is whether it should be implemented now or delayed. In this paper, the first year rate of return method is regarded as a more concise way of solving the timing of investment, At the end of Part IV, risk analysis of fishing port investments is considered. It can be handled in a number of ways, ranging from informal judgment to complex statistical analyses involving large-scale computer models, This paper recommends that evaluators of fishing port investments use the sensitivity analysis indicating exactly how much NPV will change in response to a given change in an input variable, other things held constant. Decisions regarding the amount of capacity to provide must be made in fishing port investments. Providing too much service would involve excessive capital costs. On the other hand, not providing enough service capacity would cause the waiting line of fishing vessels to become excessively long at times. Therefore, in Part V, the optimal number of berths and berth productivity in fishing port are defined as follows: Minimize E(TC) ＝ E(WC)＋E(SC) The minimum of this function is the solution and that is the optimal number of berth and berth productivity in fishing port.

• World Technopolis Review
• /
• v.4 no.1
• /
• pp.11-22
• /
• 2015

Globalization, increasing technological advancements and dynamic knowledge diffusion are moving our world closer together at a unique scale and pace. At the same time, our rapidly changing society is confronted with major challenges ranging from demographic to economic ones; challenges that necessitate highly innovative solutions, forcing us to reconsider the way that we actually innovate and create shared value. As such the linear, centralized innovation models of the past need to be replaced with new approaches; approaches that are based upon an open and collaborative, global network perspective where all innovation actors strategically network and collaborate, openly distribute their ideas and co-innovate/co-create in a global context utilizing our society's full innovation potential (Innovation 4.0 - Open Innovation 2.0). These emerging innovation paradigms create "an opportunity for a new entrepreneurial renaissance which can drive a Cambrian like explosion of sustainable wealth creation" (Curley 2013). Thus, in order to materialize this entrepreneurial renaissance, it is critical not only to value but also to actively employ this new innovation paradigms so as to derive community-driven shared value that stems from global innovation networks. This paper argues that there is a gap in existing business incubation model that needs to be filled, in that the innovation and entrepreneurship community cannot afford to ignore the emerging innovation paradigms and rely upon closed incubation models but has to adopt an "open incubation" (Ziouvelou 2013). The open incubation model is based on the principles of open innovation, crowdsourcing and co-creation of shared value and enables individual users and innovation stakeholders to strategically network, find collaborators and partners, co-create ideas and prototypes, share their ideas/prototypes and utilize the wisdom of the crowd to assess the value of these project ideas/prototypes, while at the same time find connections/partners, business and technical information, knowledge on start-up related topics, online tools, online content, open data and open educational material and most importantly access to capital and crowd-funding. By introducing a new incubation phase, namely the "interest phase", open incubation bridges the gap between entrepreneurial need and action and addresses the wantpreneurial needs during the innovation conception phase. In this context one such ecosystem that aligns fully with the open incubation model and theoretical approach, is the VOICE ecosystem. VOICE is an international, community-driven innovation and entrepreneurship ecosystem based on open innovation, crowdsourcing and co-creation principles that has no physical location as opposed to traditional business incubators. VOICE aims to tap into the collective intelligence of the crowd and turn their entrepreneurial interest or need into a collaborative project that will result into a prototype and to a successful "crowd-venture".

• The Journal of Advanced Prosthodontics
• /
• v.9 no.5
• /
• pp.321-327
• /
• 2017

PURPOSE. The aim of this study was to investigate dental arch dimensions and to classify arch shape in Korean young adults. MATERIALS AND METHODS. The sample included 50 Koreans with age ranging from 24 to 32 years. Maxillary and mandibular casts were fabricated using irreversible hydrocolloid and type III dental stones. Incisor-canine distance, $incisor-1^{st}$ molar distance, $incisor-2^{nd}$ molar distance, intercanine distance, $inter-1^{st}$ molar distance, and $inter-2^{nd}$ molar distance in both the maxillary and mandibular arch were measured using a three-dimensional measuring device. The dental arch was classified into three groups using five ratios from the measured values by the K-means clustering method. The data were analyzed with one-way analysis of variance. RESULTS. Arch lengths (IM2D, $incisal-2^{nd}$ molar distance) were 44.13 mm in the maxilla and 40.40 mm in the mandible. Arch widths (M2W, inter $2^{nd}$ molar width) were 64.12 mm in the maxilla and 56.37 mm in the mandible. Distribution of the dental arch form was mostly ovoid shape (maxilla 52% and mandible 56%), followed by the V-shape and the U-shape. The arch width for the U-shape was broader than for the other forms. CONCLUSION. This study establishes new reference data for dental arch dimensions for young Korean adults. The most common arch form is the ovoid type in the maxilla and mandible of Koreans. Clinicians should be aware of these references and classify arch type before and during their dental treatment for effective and harmonized results in Koreans.

• Culinary science and hospitality research
• /
• v.18 no.3
• /
• pp.90-107
• /
• 2012

This research has been conducted to discover the consumer's behavior in the purchase and consumption of korean alcoholic beverages. The intent of these works are to contribute to the growth of the traditional alcoholic beverages markets by giving necessary data for the marketing strategies and the development of favorite beverage to meet the consumer's tastes. The surveys have been conducted against a group of people ranging from their 20's to 60's randomly picked from seoul. The duration of the surveys was from August 1st to September 30th, 2010. We also examined the relationship between the selection attributes of traditional liquor and purchase satisfaction by consumer's life-styles. SPSS 18.0 statistical package was used to process data. Frequency analysis, factor analysis, a reliability test, K-means cluster analysis, one-way ANOVA and multiple regression were executed. As a result, through factor analysis and cluster analysis, authors identified 6 factors in the selection attributes of traditional liquor(characteristics, taste & fragrance, popularity, design, harmony, interest), 4 consumer groups(expert, fan, beginner, indifference), 4 consuming lifestyles(social oriented consuming style, maniac consuming style, pursuit of knowledge consuming style, outsider consuming style). Among the selection attributes of traditional liquor, taste & fragrance and popularity had effects on purchase satisfaction.

• Child Health Nursing Research
• /
• v.6 no.2
• /
• pp.212-223
• /
• 2000

The purposes of this research were to add to the developing knowledge base about the burden and social support of grandmothers involved with caring grandchildren, and to examine whether a significant relationship exists between their burden and social support perceived by the grandmothers. A convenience sample of 102 grandmothers was recruited from five collective apartment areas at a small city in Korea. The criteria of selection of sample were that the grandmothers were raising their grandchildren under the age of 36 months for 3 months or longer at own or gandchildren's home. The instruments used were a 15-item multidemensional burden scale and a 8-item social support scale. Both scales were self report, five point Likert type scales. The higher the score, the higher the degree of burden and social support. Data was collected by two prepared research assistants visiting subjects' home from December 10, 1998 to March 20, 1999. The collected data were analysed using mean, t-test, one-way ANOVA, and Pearson's correlation coefficient computed by SPSS software. The results were as follows. 1. In the age distribution of grandmothers, the over half of subjects(58.8%) were under 60 years old. The majority(69.6%) of subjects were married at time of data collection. 79(77.5%) of the sample reported that their perceived health status was good or over. 2. The burden of the grandmothers was not scored high, and the item means on burden scale were ranged from 2.26 to 4.19 out of 5. 'Short of private time'(4.19) had the highest score, followed by 'fatigue'(3.92), 'short of rest'(3.75), and 'short of contact with friends and neighbors'(3.62). The lowest item was 'family doesn't help me'(2.26), and followed by 'family doesn't understand me'(2.33), 'angry with family' (2.43), and 'angry while caring for grandchild'(2.60). 3. There were significant relationships between the burden and present health status(p<.01), childcaring confidence(p<.01), and motive of caring(p<.01). 4. The score of social support, was ranging from 3.61 to 4.01 out of 5. 5. The relationship between burden and social support was found to be correlated negatively. The relationship was statistically significant(γ= - .2833, p<.001). In conclusion, it was found that the burden was not high and burden of grandmothers caring grandchildren was correlated negatively to social support. Therefore, these results provide a basis for developing a nursing intervention to reduce the burden of grandmothers.