• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.2
• /
• pp.499-503
• /
• 2005

The objective of this thesis is to measure the limit of the real space where wireless Local Area Network(LAN) is used, and to apply this result as reference to set up a real Wireless LAN environment. The organized circumference was composed of Wireless LAN based on IEEE 802.11b of the American standard, and the examination is carried out on the campus. On the real condition of office environment and open space, the ratio of available distance to a signal at each distance was measured and this result was studied as data to embody wireless LAN on the campus. The measurement under an indoor environment was executed under circumstance having two wall and open space, however, was executed respectively under three circumstances : Where no obstacle, where one wall exists, and where two or more walls exist.

• Journal of Korean Library and Information Science Society
• /
• v.24
• /
• pp.243-274
• /
• 1996

The purpose of this study is to investigate the necessity, selection, organization and management of Must Books List in middle schools. A great book can change a person's life and future. Especially, reading in the juvenile period is important because of their intellectual curiosity and sensitivity. The results of the study were as follows: 1. The necessity of Must Books can be considered in two perspectives : One is the cultivation of emotion and sense of value and the other is the development of information abilities. 2. The general criteria for the selection of Must Books are whether a book is su n.0, pportive of learning activities, of extracurricular activities, and of activities for school festivals. And whether a book is contributing to the building of good characters of students or not should be considered, too. 3. The special attention should be given to such matters as the organizational and distributional ratio among subjects of the Must Books, the degree of difficulties, the ratio of books for both male and female students, the ratio of foreign books to domestics, the possibilities of further reading and the bibliographical matters. 4. The points to be duly considered for the management of Must Books List are the educational considerations, clearness of objectives, the elimination of commercialism and authoritarianism in the book selection. The Must Books List should be managed autonomously, depending on the characteristics of each school and be updated annually. However, the most important thing is that the teacher should be a good reader himself. 5. It is better to include short stories than the long one in the Must Book List. Students should be guided to read explanatory text first and then to move to the original text. And they should be exposed to books in various subjects and not to be too dependent on the Must Books List. They should be able to develop the problem solving ability through the reading of the Must Books. 6. Finally, the Must Books selection committee should be composed of both teacher librarian and subject teachers. It is desirable that books for the cultivation of emotion, for the establishment of sense of value, and for the development of information ability should be selected by consulting the various reading lists compiled by the Ministry of Education, the Board of Local Education and other authorities concerned.

• Journal of Advanced Navigation Technology
• /
• v.22 no.1
• /
• pp.31-36
• /
• 2018

In this paper, we designed and implemented an ultra wideband(UWB) antenna with band rejection characteristics. The proposed antenna consists of a planar radiation patch with slots and ground planes on both sides. Due to the slots in the radiation patch, the antenna shows band rejection characteristics. U-type slot contributes for wireless local area network(WLAN, 5.15~5.825 GHz) band rejection and n-type slot contributes for X-Band(7.25~8.395 GHz) band rejection. To make voltage standing wave ratio(VSWR) less than 2.0 for UWB frequency band except rejection bands, the shapes of planar radiation patch and ground plane was modified. The Ansoft 's high frequency structure simulator(HFSS) was used for the design process and simulations of the proposed antenna. The simulated antenna showed VSWR less than 2.0 for all UWB band excepts for dual rejection bands of 5.15 ~ 5.94 GHz and 7.02 ~ 8.45 GHz. And measured VSWR for the implemented antenna is less than 2.0 for all UWB band of 3.10~10.60 GHz excluding dual rejection bands of 5.12~5.95 GHz and 7.20~8.58 GHz.

• Journal of Korean Society for Atmospheric Environment
• /
• v.18 no.4
• /
• pp.305-316
• /
• 2002

Various air pollutants were measured at Tokchok Island in the Yellow Sea that is about 50 km distant from Incheon since April 1999. This study was undertaken to help understanding the level of air pollution and its distribution characteristics over the Yellow Sea. The geographical characteristics of the air pollution monitoring station and emission inventories of Tokchok Island are introduced. The mass concentrations and chemical compositions of TSP and P $M_{2.5}$ measured until March 2000 are discussed in this paper. The overall average mass concentrations are about 37.2 $\mu\textrm{g}$/㎥ for TSP and 18.7 $\mu\textrm{g}$/㎥ for P $M_{2.5}$ , respectively, which are similar to or a little lower than the values observed in other background sites at Kangwha and Taean. However, they are much lower than those observed at Qingdao in China. The low mass concentration and major anthropogenic ion concentrations in aerosols collected at Tokchok Island show that local sources are not dominant at Tokchok Island. The estimated average fractions of anthropogenic non-sea-salt sulfate to the total sulfate concentration of TSP and P $M_{2.5}$ are greater than 80% for both sizes. It hence suggests that the sulfate be mainly affected by anthropogenic sources. If we consider the average mass ratio of P $M_{2.5}$ to TSP, the mass fractions of anthropogenic species to P $M_{2.5}$ , and the molar ratio of nss S $O_4$$^{2-}$ to total N $O_{3-}$, it may be possible to infer that a part of anthropogenic species measured at Tokchok Island be transported from China. The characteristics of neutralization of nss S $O_4$$^{2-}$ and the particle size of major ions are also discussed.

• Steel and Composite Structures
• /
• v.36 no.1
• /
• pp.75-86
• /
• 2020

The grid structures with welded hollow spherical joint (WHSJ) have gained increasing popularity for use in industrial buildings with suspended cranes, and usually welded with steel tube (ST). The fatigue performance of steel tube-welded hollow spherical joint (ST-WHSJ) is however not yet well characterized, and there is little research on fatigue life prediction methods of ST-WHSJ. In this study, based on previous fatigue tests, three series of specimen fatigue data with different design parameters and stress ratios were compared, and two fatigue failure modes were revealed: failure at the weld toe of the ST and the WHSJ respectively. Then, S-N curves of nominal stress were uniformed. Furthermore, a finite element model (FEM) was validated by static test, and was introduced to assess fatigue behavior with the hot spot stress method (HSSM) and the effective notch stress method (ENSM). Both methods could provide conservative predictions, and these two methods had similar results. However, ENSM, especially when using von Mises stress, had a better fit for the series with a non- positive stress ratio. After including the welding residual stress and mean stress, analyses with the local stress method (LSM) and the critical distance method (CDM, including point method and line method) were carried out. It could be seen that the point method of CDM led to more accurate predictions than LSM, and was recommended for series with positive stress ratios.

• Women's Health Nursing
• /
• v.28 no.4
• /
• pp.307-316
• /
• 2022

Purpose: This study investigated the vulnerability to human immunodeficiency virus (HIV) infection and associated factors among married women in northwest Ethiopia. Methods: A community-based cross-sectional survey (n=657) was conducted from April 1 to 15, 2020, in Metema District, northwest Ethiopia, in four randomly selected kebele administrations (the lowest level of local government). The inclusion criteria were married women aged ≥18 years residing with their husbands. Logistic regression analysis was conducted to identify factors associated with married women's vulnerability to HIV infection. Results: Participants were on average 33.70±9.50 years and nearly one-fourth (n=148, 22.5%) were identified as vulnerable to HIV infection (i.e., experienced sexually transmitted disease symptoms or an extramarital affair of either spouse within the past 12 months). Only 18.9% reported sexual communication with their husband. Respondents who did not discuss the risk of HIV infection with their husbands had fivefold odds of vulnerability (adjusted odds ratio [AOR], 5.02; 95% confidence interval [CI], 1.43-17.5). Those who did not have premarital sex (AOR, 0.20; 95% CI, 0.05-0.77) had no worries about HIV infection (AOR, 0.27; 95% CI, 0.08-0.94), sufficient income (AOR, 0.56; 95% CI, 0.16-0.86), and less than four children (AOR, 0.69; 95% CI, 0.50-0.97) had decreased odds of being vulnerable to HIV than their counterparts. Conclusion: Not discussing risk of HIV infection with husband was a major factor of vulnerability to HIV infection as was premarital sex, worry about HIV, income, and number of children. Measures to strengthen couple's sexual communication and support economical stability is important for decreasing HIV vulnerability.

• Steel and Composite Structures
• /
• v.44 no.2
• /
• pp.225-240
• /
• 2022

Local responses of steel plate-concrete composite (SC) walls under impact loads are typically evaluated using design equations available in the AISC N690s1-15. These equations enable design of impact-resistant SC walls, but some essential parts such as the effects of wall size and shear reinforcement ratio have not been addressed. Also, since they were developed for design basis events, improved equations are required for accurate prediction of the impact behaviors of SC walls for beyond design basis impact evaluation. This paper presents a numerical study to construct a robust numerical model of SC walls subjected to impact loads to reasonably predict the SC-wall impact behavior, to evaluate the findings observed from the impact tests including the effects of the key design parameters, and to assess the actual responses of full-scale SC walls. The numerical calculations are validated using intermediate-scale impact tests performed previously. The influences of the fracture energy of concrete and the conservative aspects of the current design equations are discussed carefully. Recommendations are made for design practice.

• Journal of Digital Convergence
• /
• v.18 no.8
• /
• pp.21-27
• /
• 2020

This paper studies the impact of domestic and foreign economic activity on mobility among regions. The shortage of human resources and demand continues in Eastern Europeans. Especially Ukrainians, have entered the Polish labor market to make up for the scarce areas. As a result, Poland's supply and demand in Ukraine is disproportionate. Minimum wage increases are putting continued pressure on employers. Therefore, the regression equation in the form of job-seeker's economic activity ratio, y= AX²+B,(x=settlers) can be used to grasp the relationship between curves. According to the domestic and foreign workers who migrated, economic activities was rather than increasing the local population, the settlers of nearby large cities is more proportional. Empirical analysis has shown that the human resource hub has increased migration to large cities and industrial. The hub 'A'nation has been created for mobility in 4th wave re-industry, and the same re-industrialization (N₂) in other cities has attracted nearby human resources, but not settle. After all, the hub relationship between N₁ and N₂ is a mobile relationship. Due to wage inequality or a positive wellbeing chasm, workers are not settled plant area but a nearby city, or commuting between borders is easy to go into the hub central city. However, this proved on emerging from the relatively temporary settlers in the AI era.

• The Journal of Advanced Prosthodontics
• /
• v.5 no.2
• /
• pp.204-208
• /
• 2013

PURPOSE. The purpose of this study was to evaluate the effectiveness of a promotion campaign for subject recruitment and selection, and reasons of withdrawal from a prospective clinical trial of mandibular two-implant supported overdenture. MATERIALS AND METHODS. The subjects of this study were participants in a randomized controlled clinical trial for investigating prognosis of implants and overdentures with attachments. Recruited subjects were classified by gender, age, and participation motives. Withdrawal rate of the participants before and after enrollment were evaluated. RESULTS. 177 patients were recruited and 51 patients were enrolled for the trial. Among them, 40 participants eventually took part in the trial. 116 subjects (65.5%) were recruited by advertisement and 61 (34.5%) were referred by patients of the hospital or local clinics. Regarding recruitment effectiveness, newspaper recruited the largest number of participants. With respect to referral patients, the proportion of our hospital patients was higher (37/61). Subjects in their 70s comprised the largest proportion (22/51). The male to female ratio was similar (25:26). Final withdrawal rate of all subjects were 74.0%. Among the reasons for withdrawal from enrollment (n=126) presence of remaining teeth and lack of motivation were the most common reasons. CONCLUSION. To facilitate recruitment of clinical trial subjects and improve enrollment rate, it is important to obtain a sufficient number of researchers, perform promotion activity with diverse strategies, cooperate with local dentists, increase the research funding, and alleviate subjects' fear against clinical trials by thorough consultation.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.5
• /
• pp.615-627
• /
• 1997

An experiment was performed to local heat transfer coefficient and Nusselt number in the circular duct of 180.deg. bend for Re=6*10$^{4}$, 8*10$^{4}$ and 1*10$^{5}$ at swirling flow and non-swirling flow conditions. The test tube with circular section was made by stainless which has curvature ratio 9.4. The wall of test tube was heated directly by electrical power to 3.51 kw and swirling motion of air was produced by a tangential inlet to the pipe axis at the 180 degree. Measurements of local wall temperatures and bulk mean temperature of air are made at four circumferential positions in the 16 stations. The wall temperatures show particularly reduced distribution curve at bend for non-swirling flow but this effect does not appear for swirling flow. Nusselt number distributions for swirling flow which was calculated from the measured wall and bulk temperatures were higher than that of non-swirling flow. Average Nusselt number of swirling flow increased about 90 ~ 100% than that of non-swirling flow whole through the test tube. The Nu/N $u_{DB}$ values at the station of 90.deg. for non-swirling flow and swirling flow are respectively about 2.5 and 4.8 at Re=6*10$^{4}$. Also that is good agreement with Said's result for non-swirling flow. flow.