A Reinforcement Learning Approach to Access Management in Wireless Cellular Networks

Moon, Jihun,Lim, Yujin WILEY INTERSCIENCE 2017 WIRELESS COMMUNICATIONS AND MOBILE COMPUTING Vol.2017 No.-

<P>In smart city applications, huge numbers of devices need to be connected in an autonomous manner. 3rd Generation Partnership Project (3GPP) specifies that Machine Type Communication (MTC) should be used to handle data transmission among a large number of devices. However, the data transmission rates are highly variable, and this brings about a congestion problem. To tackle this problem, the use of Access Class Barring (ACB) is recommended to restrict the number of access attempts allowed in data transmission by utilizing strategic parameters. In this paper, we model the problem of determining the strategic parameters with a reinforcement learning algorithm. In our model, the system evolves to minimize both the collision rate and the access delay. The experimental results show that our scheme improves system performance in terms of the access success rate, the failure rate, the collision rate, and the access delay.</P>

Collision Reduction for Machine Type Communications in LTE-A Networks

Jihun Moon,Yujin Lim 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.9

LTE-A networks provide excellent wireless connectivity for MTC (Machine Type Communication). In order to connect a large number of MTC devices into one network, many signaling messages should be transmitted. The signaling channel is overloaded for the messages and accesses of MTC devices are failed. 3GPP specifies access class barring scheme to resolve the overload problem but leaves a specific algorithm to configure a parameter as an implementation issue. In this paper, we present an algorithm to dynamically configure a parameter based on the number of colliding devices in access class barring scheme. Through simulations, it is shown that our algorithm improves the performance compared to the original access class barring in terms of access success, access failure, collision, and access delay.

Effect of Concrete on Thermal Neutron in the Application of Neutron Tomographic Technique Using He-4 Gas Scintillation Detector

Jihun Moon,Jisu Kim,Kyung Taek Lim,Sung-woo Kwak 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1

For spent nuclear fuel transferred to dry storage facilities, it is difficult to apply safeguards approaches and long-term integrity verification due to the structural characteristics of the facility. There is a need to check the integrity of the nuclear fuel assembly before transferring it to a dry storage facility and are need to provide information on whether there are any defects. At the Korea Institute of Nuclear Nonproliferation and Control, as a non-destructive testing technology for ensuring Continuity of Knowledge (CoK) of the dry storage facilities, a methodology for reconstructing images by neutron tomographic technique from spent nuclear fuel using a He-4 gas scintillation detector was presented. It is thought that the He-4 gas scintillation detector-based technology can be used to verify the defect of the nuclear fuel assembly. This methodology must be accompanied by accurate neutron measurements. The place where the technique was conducted is surrounded by a concrete wall. Concrete contains water molecules, which can affect neutron measurements. In this study, reconstruction images based on neutron measurements and MCNP simulations are compared to verify the effects of the concrete. Neutron measurements were performed by measuring Cf-252 neutron sources in a 1/10 lab-scale TN- 32 cask with six He-4 gas scintillation detectors as an array. Neutron sources are fixed at each point in the cask, and the He-4 detector array is rotated from 0° to 360° at 10° intervals to reconstruct the image using the filtered back-projection (FBP) method. Also, in MCNP reconstructed images, there are two versions depending on whether concrete wall. The source image and ring shape were found in the measurement-based thermal neutron reconstruction image, which was similar to the simulation image that considering the concrete effects. On the other hand, in the simulation reconstruction image without the concrete, only the shape of the source was found. Thus, the effect of concrete should be considered when performing the neutron tomographic techniques using He-4 gas scintillation detectors.

Space Telescope Pre-study of KASI for the Next Decades

Bongkon Moon,Dae-Hee Lee,Young-Jun Choi,Wonyong Han,Ukwon Nam,Youngsik Park,Won-Kee Park,Duk-hang Lee,Woojin Kim,Jeong-Yeol Han,Seonghwan Choi,Jihun Kim,Jongwan Ko,Il-joong Kim,Hong-Kyu Moon 한국천문학회 2021 天文學會報 Vol.46 No.2

악성 URL 탐지 추론 모델의 분산 병렬 처리 기법

문효종(Hyojong Moon),어지훈(Jihun Eu),손시운(Siwoon Son),문양세(Yang-Sae Moon) 한국정보과학회 2020 한국정보과학회 학술발표논문집 Vol.2020 No.12

Study of the Effectiveness of a Korean Smart Transmission Grid Based on Synchro-Phasor Data of K-WAMS

Jihun Kim,Byongjun Lee,Sangwook Han,Jeong-Hoon Shin,Taekyun Kim,Sangtae Kim,Younghwan Moon IEEE 2013 IEEE transactions on smart grid Vol.4 No.1

<P>Recent technological achievement in areas of distributed computing, networking, high speed communications and digital control, as well as the availability of accurate GPS time source, are rapidly becoming the enabling factors for the development of a new generation of real time power grid monitoring tools. KDN (Korea electric power Date Network Co.) R&D department with KERI, Korea University and LSIS has embarked on long term research and development work in the field of wide area systems specifically applied to the power transmission grid in Korea. Primary focus will be on wide area measurement and monitoring, analysis, assessment technique and tools aimed at preventing the propagation of power grid instabilities. Of special interest are voltage stability and small signal stability. This project aligns with KEPCO (the Korea Electric Power Company). In this paper, case studies performed with the use of the developed system are presented.</P>

Vegetarianism as a protective factor for asymptomatic colonic diverticulosis in Asians: a retrospective cross-sectional and case-control study

( Jihun Bong ),( Hyoun Woo Kang ),( Hyeki Cho ),( Ji Hyung Nam ),( Dong Kee Jang ),( Jae Hak Kim ),( Jun Kyu Lee ),( Yun Jeong Lim ),( Moon-soo Koh ),( Jin Ho Lee ) 대한장연구학회 2020 Intestinal Research Vol.18 No.1

Background/Aims: Dietary fiber intake is considered a protective factor for diverticular disease such as diverticulitis. However, evidence for an inverse connection between dietary fiber consumption and asymptomatic colonic diverticulosis is lacking. Specifically, few studies have investigated this subject in Asians with different presentations of diverticulosis. Therefore, we assessed the protective effects of a vegetarian diet for asymptomatic colonic diverticulosis in Buddhist monks who are obligatory vegetarians for spiritual reasons compared with the general population. Methods: A retrospective, cross-sectional, case-control study was conducted in age- and sex-matched Buddhist monks and the general population who underwent colonoscopy for screening at a Korean health promotion center from August 2005 to June 2018. We compared the prevalence of asymptomatic diverticulosis between the 2 groups using a self-administered questionnaire. Results: In this study, a total of 1,316 individuals were included (Buddhist monks of 658 and general population of 658) with a mean age of 52.6±9.5 years. The prevalence of asymptomatic diverticulosis in Buddhist monks was lower compared with the general population (6.7% [44/658] vs. 10.8% [71/658], P=0.008). Buddhist monks had a higher rate of high body mass index (BMI) and metabolic syndrome. By a multivariate regression analysis model, a nonvegetarian diet (odds ratio [OR], 1.82; 95% confidence interval [CI], 1.21-2.72, P=0.004), old age (OR, 4.53; 95% CI, 1.36-15.12; P=0.014), male sex (OR, 1.91; 95% CI, 1.28-2.85; P=0.002), and a high BMI (OR, 1.50; 95% CI, 1.01-2.23; P=0.047) were independent predictors of asymptomatic diverticulosis. Moreover, a nonvegetarian diet was associated with both right-sided and left-sided diverticulosis. Conclusions: A nonvegetarian diet may increase a risk of asymptomatic colonic diverticulosis in Asians. (Intest Res 2020;18:121-129)

연속조류계산법을 이용한 대규모 풍력 발전의 정적계통 투입량 결정 알고리즘 개발

김지훈(Jihun Kim),문지혜(Ji-hye Moon),이환익(Hwanik Lee),이병준(Byongjun Lee) 대한전기학회 2011 대한전기학회 학술대회 논문집 Vol.2011 No.7

Preliminary mechanical design of GrainCams payload for the CLPS lunar rover

Bongkon Moon,Woojin Kim,Dukhang Lee,Dae-Hee Lee,Minsup Jeong,Jihun Kim,Seonghwan Choi,Min Bae Kim,Jehyuck Shin,Mingyeong Lee,ChaeKyung Sim,Sungsoo S. Kim,Young-jun Choi 한국천문학회 2023 天文學會報 Vol.48 No.1

인삼 첨가에 따른 녹차의 성분 및 품질 변화

신지훈(Jihun Shin),하서룡(Seo Ryong Ha),조경환(Kyung Hwan Cho),황정규(Jeong Gyu Hwang),심두보(Doobo Shim),손용휘(Young Whee Son),정광희(Kwang Hee Jeong),김민정(Min Jung Kim),강수영(Suyoung Kang),문두경(Doo Gyung Moon),김종철(Jong Che 한국차학회 2022 한국차학회지 Vol.28 No.1

본 연구는 차에서 느껴지는 폴리페놀의 수렴성으로 인하여 기호성이 떨어지는 문제점을 해결하기 위한 것으로서, 인삼(Panax ginseng)을 첨가해 숙성시켜 차 성분의 자극성과 수렴성 완화에 따른 성분 및 품질(맛) 변화를알아보았다. 본 연구에서의 인삼녹차 제다방식은 살청(90~110℃)→수삼 배합(녹차 5 : 수삼 1) 및 숙성(7 day)→건조(90~110℃, 수분함량 5% 이내)의 단계를 거쳤으며, 이 시료와 배합에 이용된 녹차를 무처리구로 사용하였다. 실험방법으로는 HPLC를 이용하여 당함량 및 진세노사이드를 분석하였으며, 색차분석을 이용하여 우린 물의 색(탕색), 우린 후의 엽저색을 분석하였다. 또한, 전자혀를 이용하여 신맛(SRS), 떫은맛(GPS), 짠맛(STS), 감칠맛(UMS), 매운맛(SPS), 단맛(SWS), 쓴맛(BRS)을 분석하였다. 그 결과, 당은 녹차에 비해 인삼녹차가 fructose 300%, sucrose 38.1% 가 많다는 것을 확인하였고, 인삼의 성분인 ginsenoside Rg1, Re, Rb1이 새롭게 존재함을 확인하였다. 색차 분석은 탕색의 경우 명도(L)는 인삼녹차가 4.1% 낮았으며, 황색(b)은 1.7%가 높고 적색(a)이 120.5%가 높게 나왔다. 엽저의 경우 명도(L)가 4.5% 높고, 적색(a)은 372.7%, 황색(b)은 5.8%가 높게 나왔다. 또한, 맛 분석을 통해 사람이 가장 중독성이 강한 맛인 짠맛(STS)이 녹차에 비해 인삼녹차가 26.4% 가 높게 나왔으며, 단맛(SWS) 역시 18.2% 높게 분석된 것으로 사료된다. 그리고 인삼특유의 향을 내는 성분인 isopinocampheol, (-)-globulol, (-)-spathulenol, panaxene, panaginsene, β-clovene 및 (Z)-caryophyllene과 녹차의 주요 향기성분인 linalool, linalool oxides, jasmone 및 methyl salicylate 등이 함께 측정된 결과로 비추어 보아, 인삼 녹차는 인삼 특유의 향과 녹차의향이 함께 잘 어우러져 있다고 유추해 볼 수 있다. 이러한 결과로 인삼녹차는 수렴성이 완화되어 기존의 녹차에서느껴지는 떫은맛에 대한 불편함이 줄어들고 기호성이 향상되고 향미도 풍부함을 느낄 수 있어 새로운 제품개발에활용될 가능성을 시사하였다. This study investigates the changes in the components and quality (taste) by considering the relaxation of stimulation and astringent properties of tea components subsequent to supplementation with ginseng for aging. The process for obtaining ginseng green tea for this study was as follows: salting (90~110℃) → mixing fresh ginseng (green tea 5: fresh ginseng 1) and aging (7 days) → drying (90~110℃, moisture content within 5%). The green tea used for this sample and formulation was used as the untreated group. Sugar content and analysis of ginsenosides were achieved using HPLC. Brewed leaves were evaluated for brewed color using color difference analysis, and were also subjected to taste analysis. Our results confirm that ginseng green tea contains 300% more fructose and 38.1% more sucrose compared to the control group. We further confirmed that the ginsenosides Rg1, Re, and Rb1, which are components of ginseng, were newly present. In the color difference analysis, ginseng green tea had a 4.1% lower brightness, whereas yellow and red had 1.7% and 120.5% higher brightness, respectively. Evaluation of the after-brew green, red, and yellow leaves revealed that the brightness was 4.5%, 372.7%, and 5.8% higher, respectively. In addition, taste analysis revealed that the ginseng green tea had a 26.4% higher salty taste (the most addictive taste for humans) compared to the control group, and more sweetness (18.2% higher). The volatile flavor components analysis confirmed the presence of components that impart the unique scent of ginseng, such as isopinocampheol, (-)-globulol, (-)-spathulenol, panaxene, panaginsene, β -clovene, and (Z)-caryophyllene. In addition, results of the measurements for the main scents of green tea, such as linalool, linalool oxides, jasmone, and methyl salicylate, showed that ginseng green tea has a unique blend of ginseng and green tea scents. Taken together, our results determine that the astringent properties of ginseng green tea are relieved, and the discomfort of the astringent taste felt in the existing green tea is reduced; moreover, palatability is improved, and the flavor obtained is richer.