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무선랜과 Cdma2000 이동통신망간 고속 핸드오프를 위한 이중 모드 단말의 설계 및 구현
김준하,조진성,김태현,이지철,이상도,이성원,Kim, Jun-Ha,Cho, Jin-Sung,Kim, Tae-Hyoun,Lee, Ji-Cheol,Lee, Sang-Do,Lee, Sung-Won 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.4B
cdma2000 이동통신망의 패킷데이터 서비스는 넓은 영역을 커버하는 대신에 비용이 높고 대역폭이 낮다. 반면에 무선랜의 경우 작은 지역만을 커버할 수 있지만 대역폭이 크고 비용이 낮은 특성이 있다. 그러므로 무선랜과 cdma2000 이동통신망을 연동하여 사용한다면.효율적인 서비스를 제공할 수 있다. 본 논문에서는 기존 cdma2000 이동통신망과 무선랜의 효율적인 연동을 통해서 끊김 없는 서비스를 받을 수 있는 망 연동 방안을 제안하고 이중모드 단말을 구현한다. 제안하는 망 연동 방안은 기존의 밀결합 연동의 단점을 보완한 망 구조를 가지고 있으며, 이중 모드 단말은 무선 네트워크의 상태를 파악하여 네트워크를 선택하고 자동으로 연결을 관리하도록 한다. 또한 구현된 시스템 하에서 성능 특정을 통하여 우수성을 보인다. The cdma2000 mobile network covers a wide area but its characteristics are high cost and low bandwidth. On the other hand, WLAN covers a small area like a hot spot area but its characteristics are large bandwidth and low cost. Thus we can provide efficient services when we employ an integration network between WLAN and cdma2000 mobile networks. In this paper, we propose an integration scheme between WLAN and cdma2000 mobile networks. In addition, we design and implement the dual mode terminal which receives seamless data services in the integrated network. The proposed dual mode terminal manages connections by monitoring the signal strength of WLAN and selecting a proper network. We validate the functions through the implementation of VOD and show the effectiveness through the performance measurement.
감마선 스펙트럼 비율을 이용한 매립 선원의 깊이 평가 방법론 개발 연구
김준하,정재학,홍상범,서범경,이병채,Kim, Jun-Ha,Cheong, Jea-Hak,Hong, Sang-Bum,Seo, Bum-Kyung,Lee, Byung Chae 한국방사성폐기물학회 2020 방사성폐기물학회지 Vol.18 No.1
This study was conducted to develop a method for depth assessment of embedded sources using gamma-spectrum ratio and for the evaluation of field applicability. To this end, Peak to Compton and Peak to valley ratio changes were evaluated according to <sup>137</sup>Cs, <sup>60</sup>Co, <sup>152</sup>Eu point source depth using HPGe detector and MCNP simulation. The effects of measurement distance of PTV and PTC methods were evaluated. Using the results, the source depth assessment equation using the PTC and PTV methods was derived based on the detection distance of 50 cm. In addition, the sensitivity of detection distance changes was assessed when using PTV and PTC methods, and error increased by 3 to 4 cm when detection distance decreased by 20 cm based on 50 cm. However, it was confirmed that if the detection distance was increased to 100 cm, the effects of detection distance were small. And PTV and PTC methods were compared with the two distance measurement method which evaluates the depth of source by the change of net peak counting rate according to the detection distance. As a result of source depth assessment, the PTV and PTC showed a maximum error of 1.87 cm and the two distance measurement method showed maximum error of 2.69 cm. The results of the experiment confirmed that the accuracy of the PTV and PTC methods was higher than two distance measurement. In addition, Sensitivity evaluation by horizontal position error of source has maximum error of less than 25.59 cm for the two distance measurement method. On the other hand, PTV and PTC method showed high accuracy with maximum error of less than 8.04 cm. In addition, the PTC method has lowest standard deviation for the same time measurement, which is expected to enable rapid measurement.
독거노인의 미충족 치과의료 관련요인: 2018년 지역사회건강조사 자료를 이용하여
김준하 ( Jun Ha Kim ),김소영 ( So Yeong Kim ),조경희 ( Kyung Hee Jo ),김예림 ( Ye Rim Kim ),최미진 ( Mijin Choi ) 대한예방치과·구강보건학회 2021 大韓口腔保健學會誌 Vol.45 No.2
Objectives: The purpose of the study was to investigate the factors affecting unmet dental care needs among elderly living alone. Methods: The study subjects were 19,019 elderly living by themselves, who participated in the Korea Community Health Survey 2018 (KCHS, 2018). The data were analyzed using frequency analysis, Rao-Scott chi-square test, t-test, and binary logistic regression analysis, using the SAS 9.4 software. Results: Results from the multiple logistic regression analysis revealed a higher odds ratio (OR) for unmet dental care needs among those with a monthly household income below KRW 1,000,000 (OR=1.64, 95% confidence interval, 95%CI=1.39-1.92), compared to those with an income of above KRW 2,000,000. With regards to stress levels, unmet dental care needs were more prevalent among participants in the “stress moderate” (OR=1.19, 95% CI=1.06-1.33) and “stress” groups (OR=1.68 95% CI=1.48-1.92), compared to the “no stress” group. Furthermore, the OR for unmet dental care needs was significantly higher among participants in the “depression” group (OR=1.84, 95% CI=1.61-2.11) than the “no depression” group. Conclusions: Higher unmet dental care needs were found among participants in the low monthly household income, stress, and depression groups. Further study is needed to analyze the association between factors and needs related to unmet dental care.
광산 통기수갱발파에서 전색조건이 발파효율에 미치는 영향에 관한 수치해석적 연구
김준하 ( Jun-ha Kim ),김정규 ( Jung-gyu Kim ),정승원 ( Seung-won Jung ),고영훈 ( Young-hun Ko ),( Khaqan Baluch ),김종관 ( Jong-gwan Kim ) 대한화약발파공학회 2021 화약발파 Vol.39 No.3
Ventilation shafts are pathways in mines and tunnels for the removal of dust or smoke during underground space construction and operation. In mines, blasting with long blast holes is preferred for the excavation of a ventilation shaft in the 10∼20m long crown pillar section. In this case, the bottom part of the blast hole is completely drilled in order to determine the drilling error, and this causes a problem of lowering the explosive charge and blasting efficiency. It is possible to solve the problem of explosive loading and to increase the blast efficiency by covering the curb of the blasthole by using stemming material. In this study, simulations for the blasting of a ventilation shaft were performed with various stemming lengths and the blasthole diameters(45, 76mm) using AUTODYN 2D SPH(Smooth particle hydrodynamics) analysis technique. Also the optimal bottom stemming column was derived by checking the size of the boulder and burden line according to blasting. Analysis result, blasting efficiency is lessened in case of stemming length less than 30cm and the optimal length of the stemming material should be 30cm or higher to achieve high efficiency of blasting.