• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.38-48
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• 2006

For extending of hot-spot of WLAN, (2) proposes internetworking scheme between wireless LAN (WLAN) and mobile ad-hoc network (MANET), which employ the same layer-2 protocol with different mode. Compared to internetworking schemes between UMTS (Universal Mobile Telecommunications Systems) and WLAN (3-4), the scheme from (2) has relatively low overhead and latencies because WLAN and MANET are physically and logically similar to each other. However, the mode switching algorithm proposed in r2] for internetworking between WLAN and MANET only considers signal strength and determines handoff, and mobile nodes following a zigzag course in pollution area may perform handoff at short intervals. Furthermore, (2) employs mobile IPv6 (MIPv6) at base, which brings still high delay on handoff and overhead due to signal message exchange. In this paper, we present optimized internetworking scheme between WLAN and MANET, modified from (2). To settle ping-pong handoff from (2), we propose adaptive mode switching algorithm. HMIPv6 is employed for IP connectivity and mobility service in WLAN, which solves some shortcomings, such as high handoff overhead and vulnerable security. For routing in MANET, OLSR is employed, which is a proactive Protocol and has optimally reduced signal broadcasting overhead. OLSR operates with current P protocol compatibly with no change or modification. The proposed internetworking scheme based on adaptive mode switching algorithm shows better performance than scheme from (2).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.422-429
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• 2007

Location awareness is one of the key functionalities to build an U-city. Recently, many of works of the location-aware systems are emerging to commercially apply to on-going large-scale apartment complex based on U-city. As dwellers or cars being attached with active tags are moving in the U-city complex, the active tags periodically broadcast their own identifiers and receivers fixed along the street or in building use those information to calculate location of them. There are several issues to be considered for such an environment. The first is that the number of active tags operating in the same region are large as much as tens of thousands, and the second is that the active tags should be alive without change of batteries more than a year, hence low power consumption is very important. In this paper we propose i) a new architecture for location-aware system considering such issues, ii) technical issues to implement it using active tags, and iii) a mathematical analytic model to investigate overall performance and verify it by comparing with actual experimental results. Through the analysis we can show the theoretical boundary of the lowest packet loss rate and the maximum number of tags with acceptable performance for the systems based on active tags. The results can be applied to practical design of location-based systems of U-City projects.

• Journal of The Korean Ophthalmological Society
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• v.59 no.12
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• pp.1173-1180
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• 2018

Purpose: We evaluated the postoperative accuracy of intraocular lens power prediction for patients undergoing phacotrabeculectomy and identified preoperative factors associated with refractive outcome in those with primary open-angle glaucoma (POAG). Methods: We retrospectively reviewed the medical records of 27 patients who underwent phacotrabeculectomy to treat POAG. We recorded all discrepancies between predicted and actual postoperative refractions. We compared the data to those of an age- and sex-matched control group that underwent uncomplicated cataract surgery during the same time period. Preoperative factors associated with the mean absolute error (MAE) were identified via multivariate regression analyses. Results: The mean refractive error of the 27 eyes that underwent phacotrabeculectomy was comparable to that of the 27 eyes treated via phacoemulsification (+0.02 vs. -0.01 D, p = 0.802). The phacotrabeculectomy group exhibited a significantly higher MAE (0.65 vs. 0.35 D, p = 0.035) and more postoperative astigmatism (-1.07 vs. -0.66 D, p = 0.020) than the phacoemulsification group. The preoperative anterior chamber depth (ACD) and the changes in the postoperative intraocular pressure (IOP) were significantly associated with a greater MAE after phacotrabeculectomy. Conclusions: POAG treatment via combined phacoemulsification/trabeculectomy was associated with greater error in terms of final refraction prediction, and more postoperative astigmatism. As both a shallow preoperative ACD and a greater postoperative change in IOP appear to increase the predictive error, these two factors should be considered when planning phacotrabeculectomy.

• Korean Journal of Social Welfare Studies
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• v.40 no.3
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• pp.181-211
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• 2009

Asian Americans are one of the fastest growing minority groups in the United States. One of the stereotypes associated with Asians is that they are more likely to choose careers in science, medicine, and engineering rather than social science, inclusive of social work, mass communication, or humanities (Leong & Serafica, 1995; Tang et al., 1999). This occupational stereotyping of Asians is not just a myth in that only a few Asians choose social work as a career (Lennon, 2005; NASW, 2006). Few studies exist on Asian Americans who do not choose Asian stereotypical career choices, such as social work. Acknowledging this lack of research, the present study was developed to explore the relationships between factors that may influence Asian Americans who choose social work as their career. Based on Social Cognitive Career Theory (Lent, Brown, & Hackett, 1994), it was hypothesized that acculturation and family immigration status influenced parental involvement, disapproval by significant others as a perceived career barrier among Asian American social workers. A cross-sectional survey design was used in this study. The sample was derived from the members'database of the National Association of Social Workers (NASW). A total of 900 were randomly chosen among 1,802 of Asian American social workers in the NASW database, and 370 Asian American social workers participated in this study with 41 percent of a return rate. Quantitative data were collected through standardized measurements: Suinn-Lew Asian Self-Identity Acculturation Scale (Suinn, Rickard-Figueroa, Lew, & Vigil, 1987); Career Barriers Inventory Revised (Swanson, et al., 1996); and eight items from Tang et al.'s (1999) Asian American Career Development Questionnaire. The data were collected through a combined method of an online survey with option of a paper mail-return questionnaire. Results of the study found significant group differences among family immigration status groups on parental involvement, and perceived likelihood and hindrance of disapproval by significant others. The group of the 2nd generation reported the highest scores of parental involvement among the family immigration status groups. Also, Asian American social workers who represented the 3rd and higher generation of immigration reported lowest perceived likelihood and hindrance scores of disapproval by significant others. However, there was no significant multivariate effect of acculturation on parental involvement, and perceived likelihood and hindrance of disapproval by significant others. Implications and limitations of this study, as well as suggestions for future research, are discussed.

• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.77-86
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• 2021

This study explored the role of perceived stress in Korean high school students' suicidal thought. In so doing, we also investigated the mediating role of high school students' internet use time and amount of drinking alcohol. For this, 2019 Korean adolescent health behavior survey was used. Complex design multivariage logistic regression analysis revealed that high school students' perceived stresss(OR:5.607, 95%CI:5.077-6.191) and amount of drinking(ranging from OR:1.412, 95%CI:1.159-1.720 to OR:2.325, 95%CI:1.928-2.803) played a significant role in their suicidal thoughts. Internet use time and amount of alcohol consumed were found to play a mediating role. Implications of the results are discussed. Therefore, since internet use mediated suicidal thinking among adolescents, it is necessary to develop a intervention program or message for them.

• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.19-29
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• 2011

In order to assess the influences of bottom sediment on water quality, following measurement were made. (1) Estimations of pollutant loads from the bottom sediment based on mass balance concept, (2) measurements of pollutant concentrations in the sediment to assess the pollution level and influence potential, (3) in situ and laboratory measurements of Sediment Oxygen Demants (SOD) and pollutant load (sediment release) from bottom sediment. Analyses of inflow and outflow loadings using simple mass balance show that there are some variations found according to the pollutants. However, there is no consistent evidence that the sediment can be a source of pollutants. Pollutant concentrations in the sediment range 16~724.8 mg/kg (COD), 1.68 ~12.64 mg/kg (T-P), 5.6~76.8 mg/kg (T-N), 0.32~21.6 mg/kg ($NH_3$-N), 0.092~0.544 mg/kg ($NO_2$-N), 4.8~18.4 mg/kg ($NO_3$-N), and 1.59~11.23 mg/kg ($PO_4$-P). Measured SOD ranges $0.190{\sim}0.802g{\cdot}m^{-2}{\cdot}d^{-1}$ and measured release rate ranges $-1618.42{\sim}10mg/m^2{\cdot}d$(COD), $-12{\sim}16mg/m^2{\cdot}d$(T-P), $-197.37{\sim}140mg/m^2{\cdot}d$(T-N), $0.4{\sim}74.32mg/m^2{\cdot}d$($NH_3$-N), $-2.04{\sim}0.8mg/m^2{\cdot}d$ ($NO_2$-N), $-70{\sim}40mg/m^2{\cdot}d$ ($NO_3$-N), and $-26.11{\sim}28.55mg/m^2{\cdot}d$($PO_4$-P). All study results indicate that bottom sediments in the Seoha weir show only limited effects on the water quality. It implies that sediment dredging is not an effective option or management measure to reduce pollutant loading.

• Food Science of Animal Resources
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• v.41 no.5
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• pp.802-815
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• 2021

To investigate the effect of postmortem phases on lamb meat quality, the physicochemical quality, microstructure and water mobility of oyster cut, short loin, knuckle and silverside muscles from Small-Tail Han sheep were evaluated in the pre-rigor, rigor mortis and post-rigor phases. Pre-rigor lamb meat had higher pH and water holding capacity (WHC), whereas lower CIE L^*, b^*, hue angle values than rigor mortis and post-rigor meat (p<0.05). The Warner-Bratzler shear force (WBSF) values were higher in rigor mortis short loin and silverside than their pre-rigor and post-rigor counterparts, pre-rigor short loin had lower WBSF value than its post-rigor counterpart (p<0.05). Muscle fibers shrank laterally and longitudinally during the onset of rigor mortis. Rigor mortis and postrigor lamb meat exhibited wide I-bands, dark A-bands, short sarcomeres and large inter-myofibrillar spaces. The shift of immobilized water to free water and repulsion from the intra-myofibrillar space to the extracellular space result in the increase of water loss in rigor mortis and post-rigor lamb meat. The results of the principal component analysis (PCA) indicated that rigor mortis and post-rigor lamb meat had similar quality properties but different from pre-rigor lamb meat. In conclusion, the lamb meat in the pre-rigor phase had good tenderness, color and WHC. The results of this research could provide some theoretical references for lamb meat production and processing.

• Journal of Life Science
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• v.32 no.10
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• pp.792-802
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• 2022

In this study, the antioxidant and antibacterial activities of Sophora japonica extracts were investigated to determine the potential of S. japonica as a functional food and medicinal materials. S. japonica was divided into flowers, fruits, and branches, and ethanol extraction was used. The total polyphenol and flavonoid contents were significantly higher in the flower and fruit extracts than in the branch extracts, but the ABTS and DPPH radical scavenging activity and ORAC value were higher in the branch extracts. Among the ethanol extracts of S. japonica, branch extracts showed strong antibacterial activity against Porphyromonas gingivalis, and the MIC was 0.2 mg/ml. Branch extracts showed bacteriostatic activity against P. gingivalis at a concentration of 0.4 mg/ml or less and bactericidal activity at a concentration of 0.6 mg/ml or more. Biofilm biomass production and cell growth of P. gingivalis in the culture medium treated with the branch extract at a concentration of 0.2-2.0 mg/ml were significantly decreased in a concentration-dependent manner. In addition, the mRNA expression of fimA and mfa1 associated with fimbriae formation in these cultures was suppressed in a concentration-dependent manner. Based on these results, S. japonica branch extracts can be used as functional food and medicinal materials, as demonstrated by their antioxidant and antibacterial activities against P. gingivalis and the inhibition of biofilm formation resulting from P. gingivalis.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.791-802
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• 2021

In Korea, the cities continue to deteriorate, while the vacant houses in the small local towns emerge as a serious social problem. Despite the vacant houses emerge as a serious social problem in the small local towns as well as in the large cities, the basic researches into them are yet to be conducted on a full scale. Thus, in order to know about the spatial distribution of the vacant houses, this study conducted the square analysis and the kernel density analysis. As a result, it was confirmed that the vacant houses in Okcheon-gun had certain crowding forms and characteristics at the level of statistical significance. Next, in order to examine the distribution of the vacant houses in terms of the accessibility to the living SOC facilities, the GIS network analysis was performed, focusing on the major facilities and road networks. As a result, it was found that the better the accessibility to the living SOC facilities such as medical and well-being was, the ratio of the vacant houses was lower. In contrast, it was found that the accessibility to the obligatory facilities such as public administration and educational facilities did not have any important effects on the distribution of the vacant houses. All in all, through this study, the spatial distribution of the vacant houses in the small local town and their accessibility to the major SOC facilities could be analyzed.

• The Journal of the Korea Contents Association
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• v.22 no.2
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• pp.794-802
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• 2022

This retrospective study was to investigate the characteristics of unplanned readmission and factors affecting readmission within 30 days of discharge in patients who underwent heart valve surgery through electronic medical records. The participants were 423 unplanned re-hospitalization within 30 days after heart valve surgery at a tertiary hospital in Seoul from January 2018 to August 2019. A total of 48 patients (11.3%) were unplanned readmissions, and the most common causes were atrial fibrillation in 13 cases (27.1%) and pain at the surgical site in 13 cases (27.1%). Other causes were: 10 cases (20.8%) of warfarin inappropriate treatment concentration, 7 cases of general weakness (14.6%), 5 cases of hypotension (10.4%), 4 cases of pericardial effusion (8.3%), 3 cases of surgical wound infection (6.3%), 3 cases of hemorrhage (6.3%), 3 cases of high fever (6.3%), and 1 case of cerebral infarction (2.1%). Variables influencing readmission were history of cancer (OR = 2.60, 95% CI 1.13-6.03, p = .025) and the patients who went to a home rather than a hospital after discharge (OR = 2.91, 95% CI 1.33-6.36, p = .008), as a type of valve surgery, mitral valve valvuloplasty had a higher readmission rate than aortic valve replacement (OR = 1.21, 95% CI 1.21-4.98, p = .012). In order to reduce unplanned readmissions, an tailored education program is needed to enable patients and caregivers to manage their comorbid chronic diseases before discharge and assess risk factors for readmission in advance.