• Journal of fish pathology
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• v.14 no.2
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• pp.97-102
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• 2001

Olive flounder, Paralichthys olivaceus known as an one of the major aquacultured species in Korea were exposed to cadmium(Cd) with different protocols and analyzed the effects of exposure on the immune response. Antibody levels in sera of the group exposed to Cd(20ppb) by immersion method from 2 weeks before immuniztion with formalinised Edwardsiella tarda(E. tarda) KFE entigen to the end of experiment reached to peak level faster than that of the non-exposed group. After this peaking time the levels decreased much at a faster rate compared to the non-exposed group. This tendency was also appeared in the numbers of specific antibody secreting cells(SASC) analyzed with the enzyme-linked immunospot (ELISPOT)-assay technique in the splenocytes of the experimental groups exposed to Cd with different ways. Interestingly, the group exposed to Cd for 2 weeks before immunization also showed increased numbers of SASC unlikely the antibody production and suggested a more critical influence of cadmium exposure in early stage of immune reaction. Artificial infection with live E. tarda KFE induces 100% mortality in the flounder exposed to cadmium throughout the experimental period from two weeks before the immunization. It may imply that some other factors related to specific immunity are involving in the defence system of flounder exposed to Cd. Taked together. Cd exposure may induce temporaily stimulatory or indhibitory effects on the immune reaction, but suppress the physiological systems for the resistant against the infective agents with other toxic effects.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.144-151
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• 2005

Erosion is believed to be the predominant cause of teeth wear in children and young adults, although there will at ways be a contribution from attrition and abrasion. The pH of cola is known to be low and have, therefore, been implicated in the increasing incidence of erosion. The aim of present study was to evaluate the effect of cola on the progression of erosive demineralization in human enamel using demineralization model in vitro. Six groups of human enamel slap were immersed(5 min each bath) in fresh cola, with immersions taking place with or without agitation, and under 3 regimes of frequency intake(low intake, 1 immersion/day; medium, 5/day; high, 10/day). Quantitative assessments of surface erosion were done over an 8-day interval using surface microhardness testing. 1. The average pH of cola was 2.5, which was acidic enough to cause tooth erosion. 2. All the enamel specimen exposed to cola showed erosion like lesions and surface hardness decreased in proportion to the length of immersion (p<0.05). 3. The surface hardness of enamel decreased in proportion to the frequency of immersion (p<0.05). 4. Increased degassing from the drink by gitation accelerated the enamel softening compared with those without agitation.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.322-328
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• 2007

The first molar is important for mastication and also it plays roles to formation of vertical occlusion and growth of jaw bone after mixed dentition. Impaction of mandibular first molar can result in a short lower facial height, formation of a follicular cyst, pericoronal inflammation, resorption of the roots of neighboring teeth and malocclusion. The options of treatment plans are as follows; observation, surgical exposure, orthodontic traction, surgical relocation and extraction. Surgical exposure could be considered as a basic treatment plan. For surgical exposure it is important to maintain patent channel between the crown and the normal eruptive path into the oral cavity, many techniques including cementation of a celluloid crown, packing with zinc oxide-eugenol surgical pack are used. In these cases, we could observe spontaneous eruption of mandibular first molar using surgical exposure with or without removal of odontoma. Also we could obtain the main patency effectively and conveniently by using surgical pack and translucent retainer.

• Journal of dental hygiene science
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• v.8 no.4
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• pp.255-260
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• 2008

The purposes of this study were to examine the effect of 35% hydrogen peroxide (HP) bleaching agent on the changes in physical and chemical characteristics of tooth. The bleached teeth showed an apparent color changes. The whiteness increased linearly within the tested period as the period of bleaching increased. The microhardness between bleached groups after bleaching showed any statistically significant difference according to the paried t-test. The bleached enamel surface showed any apparent morphological changes compared to the enamel which was stored in distilled water only. The difference of the total mineral contents for the distilled water and hydrogen peroxide did not show statistical significance. These results demonstrated that bleaching using 35% hydrogen peroxide were adversely affects application time of experimental group and may confirm the safety of using these agents for a short time in dentist-monitored bleaching.

• The Journal of the Convergence on Culture Technology
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• v.7 no.2
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• pp.35-48
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• 2021

This study is an attempt to establish a model and identify the relationship between the individual characteristics of college students, Internet usage characteristics, exposure to pornography, and anti-social sexual perception. The subjects of the study were 360 college students aged 18 or older in B city, and the collected data were analyzed using the IBM SPSS 21.0 and AMOS 22.0 programs. The goodness-of-fit index of the modified model met the acceptance criteria (𝛘²/df=2.786, GFI=.95, AGFI=.92, SRMR=.06, RMSEA=.07, NFI=.89, CFI=.93, TLI=.90). According to the results of path analysis, the variables that directly affect anti-social sexual perceptions of college students were personal characteristics and exposure to pornography, and the variable with indirect effect was the Internet usage characteristics. The biggest direct effect on anti-social sexual perception was exposure to pornography, and it was confirmed that exposure to pornography was directly affected by personal characteristics and Internet usage characteristics. Therefore, in order to reduce anti-social sexual perceptions among college students, measures should be taken to control personal characteristics and Internet usage characteristics that directly affect the level of exposure to pornography.

• Korean Journal of Culture and Social Issue
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• v.27 no.3
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• pp.237-258
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• 2021

The purpose of this research was to empirically explore the association between exposure to news of the nth Room Case, indirect trauma, and beliefs about the world among adults in their 20s. A total of 228 adults in their 20s participated in an online survey designed to study the association above. Analysis using SPSS 25.0 showed that participants who were exposed to more related news immediately after the nth Room case was revealed experienced a higher level of indirect trauma. Furthermore, indirect trauma fully mediated the relationship between exposure to the news of the nth Room Case and beliefs about the world. This study empirically demonstrated the impact of news exposure on beliefs about the world through indirect trauma, suggesting that, like disasters, sex crimes can cause indirect trauma to third parties through the news. However, this study was limited to adults in their 20s, and most of the participants were women; therefore, future studies using samples representing demographically more diverse groups are needed. Future research could also examine the possibility of emotional contagion mediating or moderating the relationship between news exposure and indirect trauma.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.5
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• pp.20-29
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• 2024

The chloride diffusion coefficient is a critical indicator for assessing the durability of concrete marine substructures. This study develops a prediction model for the chloride diffusion coefficient using data from concrete bridges located in marine exposure zones (atmospheric, splash, tidal), an aspect that has not been considered in previous studies. Chloride profile data obtained from these bridge substructures were utilized. After data preprocessing, machine learning models, including Random Forest (RF), Gradient Boosting Machine (GBM), and K-Nearest Neighbors (KNN), were optimized through hyperparameter tuning. The performance of these models was developed and compared under three different variable sets. The first model uses six variables: water-to-binder (W/B) ratio, cement type, coarse aggregate volume ratio, service life, strength, and exposure environment. The second model excludes the exposure environment, using only the remaining five variables. The third model relies on just three variables: service life, strength, and exposure environment factors that can be obtained from precision safety diagnostics. The results indicate that including the exposure environment significantly enhances model performance for predicting the chloride diffusion coefficient in concrete bridges in marine environments. Additionally, the three variable model demonstrates that effective predictions can be made using only data from precision safety diagnostics.

• Journal of Service Research and Studies
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• v.14 no.2
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• pp.1-17
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• 2024

One of the most important decisions for managers in the online banner advertising industry, is to choose the best banner alternative for exposure to customers. Since it is difficult to know the click probability of each banner alternative in advance, managers must experiment with multiple alternatives, estimate the click probability of each alternative based on customer clicks, and find the optimal alternative. In this reinforcement learning process, the main decision problem is to find the optimal balance between the level of exploitation strategy that utilizes the accumulated estimated click probability information and exploration strategy that tries new alternatives to find potentially better options. In this study we analyze the impact of word-of-mouth effects and the number of alternatives on the optimal exploration-exploitation strategies. More specifically, we focus on the word-of-mouth effect, where the click-through rate of the banner increases as customers promote the related product to those around them after clicking the exposed banner, and add it to the overall reinforcement learning process. We analyze our problem by employing the Multi-Armed Bandit model, and the analysis results show that the larger the word-of-mouth effect and the fewer the number of banner alternatives, the higher the optimal exploration level of advertising reinforcement learning. We find that as the probability of customers clicking on the banner increases due to the word-of-mouth effect, the value of the previously accumulated estimated click-through rate knowledge decreases, and therefore the value of exploring new alternatives increases. Additionally, when the number of advertising alternatives is small, a larger increase in the optimal exploration level was observed as the magnitude of the word-of-mouth effect increased. This study provides meaningful academic and managerial implications at a time when online word-of-mouth and its impact on society and business is becoming more important.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.407-408
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• 2003

다중입력조건에 따른 단일 출력퍼지시스템인 인구밀도와 도로조건에 따른 소개속도의 모델링시스템에서는 인구밀도와 도로조건의 퍼지멤버쉽에 대한 소개속도의 상승작용을 확인할 수 있었다. 그러나 도로조건을 평가하는 방법을 포장과 비포장으로만 구분함으로 인해 발생하는 퍼지추론과정에서 비탄력성은 향후 도로조건에 대한 세밀한 조사를 통하여 퍼지멤버쉽함수의 형태를 재고해야 할 것으로 판단된다. 실제 원자력시설에서 발생할 수 있는 사고의 경우 방사능에 노출될 수 있는 일반대중은 방사능에 대한 깊은 지식을 가지지 못하는 경우가 대부분이다. 따라서 차폐효과 혹은 소개속도를 정량적으로 파악하기 힘든 경우가 많다. 따라서, 이러한 퍼지시스템은 방사선 비상대응 시스템을 개발하는 의사결정자나 비상시 방사능에 노출되는 사람들의 대응 방식을 모델링하는데 유용할 것으로 판단된다.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.220-222
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• 2007

자연재해 및 전력 시스템의 복잡성, 외부 노출 등으로 인해 전력 설비는 언제나 고장에 노출되어 있다. 전력회사는 전력의 안정성과 신뢰도 확보를 위해 끊임없이 노력하고 있지만 전력설비의 자그마한 이상에도 그 파급효과는 상당히 클 수 있다. 이에 선진 국가와 기업에서는 전력설비의 예방진단에 대한 많은 관심과 기술 개발이 이루어지고 있으며, 제품화되어 출시되고 있는 실정이다. (주)효성에서는 변압기 진단을 위한 센서 및 IED가 포함된 지능형 변압기(Intelligent Power Transformer)용 Local Unit을 개발하였다.