• ETRI Journal
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• v.37 no.5
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• pp.856-866
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• 2015

A heterogeneous network (HetNet) is a network topology composed by deploying multiple HetNets under the coverage of macro cells (MCs). It can improve network throughput, extend cell coverage, and offload network traffic; for example, the network traffic of a 5G mobile communications network. A HetNet involves a mix of radio technologies and various cell types working together seamlessly. In a HetNet, coordination between MCs and small cells (SCs) has a positive impact on the performance of the networks contained within, and consequently on the overall user experience. Therefore, to improve user-perceived service quality, HetNets require high-efficiency network protocols and enhanced radio technologies. In this paper, we introduce a 5G HetNet comprised of MCs and both fixed and mobile SCs (mSCs). The featured mSCs can be mounted on a car, bus, or train and have different characteristics to fixed SCs (fSCs). In this paper, we address the technical challenges related to mSCs. In addition, we analyze the network performance under two HetNet scenarios-MCs and fSCs, and MCs and mSCs.

• ETRI Journal
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• v.36 no.1
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• pp.31-41
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• 2014

The heterogeneous network (HetNet) has been discussed in detail in the Long-Term Evolution (LTE) and LTE Advanced standards. However, the standardization of High-Speed Packet Access HetNet (HSPA HetNet) launched by 3GPP is pushing at full steam. Interference coordination (IC), which is responsible for dealing with the interference in the system, remains a subject worthy of investigation in regard to HSPA HetNet. In this paper, considering the network framework of HSPA HetNet, we propose a quasi-distributed IC (QDIC) scheme to lower the interference level in the co-channel HSPA HetNet. Our QDIC scheme is constructed as slightly different energy-efficient non-cooperative games in the downlink (DL) and uplink (UL) scenarios, respectively. The existence and uniqueness of the equilibrium for these games are first revealed. Then, we derive the closed-form best responses of these games. A feasible implementation is finally developed to achieve our QDIC scheme in the practical DL and UL. Simulation results show the notable benefits of our scheme, which can indeed control the interference level and enhance the system performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.462-483
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• 2016

The research on optimization of cellular network's energy efficiency (EE) towards environmental and economic sustainability has attracted increasing attention recently. In this survey, we discuss the opportunities, trends and challenges of this challenging topic. Two major contributions are presented namely 1) survey of proposed energy efficiency metrics; 2) survey of proposed energy efficient solutions. We provide a broad overview of the state of-the-art energy efficient methods covering base station (BS) hardware design, network planning and deployment, and network management and operation stages. In order to further understand how EE is assessed and improved through the heterogeneous network (HetNet), BS's energy-awareness and several typical HetNet deployment scenarios such as macrocell-microcell and macrocell-picocell are presented. The analysis of different HetNet deployment scenarios gives insights towards a successful deployment of energy efficient cellular networks.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.450-451
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• 2008

Amorphous silicon Solar cell has n-i-p structure in general, and each layer's thickness and doping concentration are very important factors which are as influential on efficiency of salar cell. Using AFORS HET simulation to get the high efficiency, by adjusting n layer's thickness and doping concentration, p layer's doping concentration. The optimized values are a-Si:H(n)'s thickness of 1nm, a-Si:H(n)r's doping concentration of $2\times10^{20}cm^{-3}$, a-Si:H(p+)r's doping concentration of $1\times10^{19}cm^{-3}$. After optimization, the solar cell shows $V_{oc}$=679.5mV, $J_{sc}$=39.02mA/$cm^2$, FF=83.71%, and a high Efficiency=22.21%. Though this study, we can use this study for planning or manufacturing solar cell which has high efficiency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.454-455
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• 2008

태양전지의 효율은 실리콘 자체의 특성에 의해서 결정 되거나 완성된 실리콘을 통해 태양전지를 제조하는 과정에서 웨이퍼의 두께와 도핑 농도의 조절을 통해 효율을 변화 시킬 수 있다. 높은 효율을 갖는 태양전지 설계를 위해 태양전지 시뮬레이터인 AFOS HET 프로그램을 이용하여 태양전지 웨이퍼 두께와 acceptor의 도핑 농도를 조절하였다. 최적화 결과 80nm ZnO, $300{\mu}m$ c-Si(p), 1nm a-Si(i), 1nm a-Si(n), $1{\mu}m$ Ag, acceptor의 도핑 농도 $7\times10^{16}cm^{-3}$ 에서 $V_{oc}$=697.7mV, $J_{sc}$=42.15mA/$cm^2$, $P_{max}$=0.0247W/$cm^2$, FF=83.51%, Eff=24.56%의 고효율을 얻을 수 있다. 본 연구를 통하여 태양전지 설계나 제조 시에 연구비를 절감할 수 있고 높은 효율의 태양전지로 접근할 수 있다.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.3
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• pp.320-334
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• 2014

Over the last two decades, numerous experimental and numerical efforts have examined physical phenomena in plasma discharge devices. The physical mechanisms that govern the anomalous electron diffusion from the cathode to the anode in the Hall Effect Thruster (HET) are not fully understood. This work used 1-D numerical method to improve our understanding and gain insight into the effect of the anomalous electron diffusion in the HET. To this end, numerical solutions are compared with various experimental HET performance measurements and the effects of anomalous electron diffusion are analyzed. The relationships between the anomalous electron diffusion and important parameters of the HET are also studied quantitatively. The work identifies the cathode mass flow rate fraction, radial magnetic field distribution, and discharge voltage as significant factors that affect anomalous electron diffusion. Additionally, the study demonstrates a computational process to determine the radial magnetic field distribution required to achieve specific thruster performance goals.

• Journal of the Korean Home Economics Association
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• v.35 no.5
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• pp.33-48
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• 1997

The purpose of this study was to examine the differences of self-confidence and satisfaction level in teaching home economics between home economics majored teachers(HET) and other subject majored teachers(OST). The subjects of this study were 192 home economics teachers randomly selected from 96 middle schools all over the country. The data was collected from 16, september to 12, October, 1996, and was analyzed with descriptive statistics, crosstables, and t-test using SAS program. The major finding were as follows: 1) In general, home econimics is taught mostly by OST in boy' middle school. 92% of OST is employed in boy' middle school and 89.13% of them is employed in private boy' middle school. 2) OST had less in-service experiences than HET on sixth revised curriculum, and had lower recognition than HET on the goal, content, teaching method, evaluation of home economics. 3) There were significant difference on the level of self-confidence and satisfaction in teaching home economics between HET and OST.

• The Korea Journal of Herbology
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• v.30 no.2
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• pp.19-24
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• 2015

Objectives : The experiment was performed to investigate promotive effects of haeae-tang (HET) extract, a traditional Korean medicinal recipe, on hair growth, protein and gene expression in hair-removed C57BL/6. Methods : In experiment, animals were divided into 3 groups including normal (vehicle), HET ethanol extract and 5% minoxidil-treated groups (Minoxidil, positive control). The vehicle or testing samples were daily treated with 0.2ml per on hair-shaved dorsal skin of C57BL/6mice for 15 days. Effects of testing samples on hair growth was monitored through phototrichogram analysis by folliscope on the initial, $5^{th}$, $10^{th}$, $15^{th}$ day, respectively. Also, gene and protein expressions of vascular endothelial growth factor (VEGF) and Insulin like growth factor-1 (IGF-1), relevant to hair growth, were examined. Results : Hair density and hair thickness of Minoxidil treated-group was significantly increased compared to that of vehicle application on the $15^{th}$day, respectively. Dorsal hair density of HET treated-group was significantly increased compared to that of vehicle application on the $15^{th}$day. In addition, the Minoxidil group significantly increased the expression of cutaneous IGF-1 protein and mRNA compared to that of the vehicle-applied group on the $15^{th}$ day. And HET-treated group significantly increased the expression of dorsal VEGF protein compared to that of the vehicle-applied group on the $15^{th}$ day. Conclusions : These results suggest that this Korean medicinal recipe, HET has promoting activity on hair growth in an Alopecia animal model thus it can be used as a material of agent or products for improvement or prevention of alopecia.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.2
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• pp.129-138
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• 1999

피부 전용 제재 개발을 위해 요구되는 동물 대체 시험법 중 가장 적극적으로 연구가 행하여지곤 실제 실용화가 예상되는 것은 안점막 자극 시험으로 지금까지 여러 가지 방법이 개발되었지만 그 중 계란 유정란의 응모요막(CAM)을 이용한 방법이 현재 가장 활발히 진행되고 있다. 이 방법이 일부 국가에서 이미 안점막 자극 시험 동물 대체 시험법으로 공인되었으며 현재까지도 validation 연구를 활발히 진행하고 있다. 본 연구에서도 국내에 적합한 안점막 자극 시험 동물 대체 시험법의 공인 시험법 개발 및 validation study를 목표로 계란 유정란의 응모요막을 이용한 방법 중 HET-CAM 방법을 시행하였으며 안점막 동물 대체 시험법으로 확립하고자 하였다. 틴ET-CAM 방법의 보완을 위해 배양된 세포를 통해 자극도를 측정할 수 있는 방법인 Cytotoxicity test를 도입하여 시행하였으며 두 방법의 data들을 분석하여 validation study를 수행하였다. 국내 유수의 6개 장업사가 본 연구에 참가하여 20가지의 화장품 전용제재를 대상으로 1차, 2차 validation study 를 진행하였다. HET-CAM test, Draize eye irritation test, Cytotoxicity test 측정 결과 HET-CAM 의 “Q” 수치는 대부분 강자극 수치인 2 이상이었고 10% sodium hydroxide가 가장 높은 수치를 보였으며 Tween 20(sorbitanpolyoxyethylene monolaurate) 100%가 가장 낮은 수치를 보였다. In vi패의 경우 10% sodium hydroxide가 가장 높은 수치를 보였으며 30군 propylene glycol 이 가장 낮은 자극수치를 보였다. HET-CAM test 와 Draize eye irritation test, Cytotoxicity test 간의 상관성 분석은 linear correlation coefficient 와 rank correlation coefficient를 구하여 비교하였으며 6개 장업사(A-F)의 실험실에서의 HET-CAM test 결과를 취합하여 각각 두 실험실간의 상관관계(linear correlation)를 분석하였다. Linear correlation coefficient 분석 결과를 보면 전반적으로 상관관계가 0.589 - 0.954의 범위였으며, 특히 A사와 B사 사이의 경우 0.954이었으며, E사와 D사 사이의 경우 0.942로 높은 상관관계를 보였다. 그 외에도 A사와 D사 사이의 경우(0.589)와 B사와 D사 사이의 경우(0.638)를 제외하고는 대체로 높은 상관관계를 나타내었다.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.32-38
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• 2017

Prion is a group of the proteins known for its infection mechanisms of Creutzfeldt-Jakob disease (CJD) and other diseases. Solved structures and proven biological roles of fungal prions add tremendous potential to conducting computational simulations. Our research focuses on the binding dynamics of HET-s(218-289), one of the heterokaryon fungal prion originated from Podospora anserina, by calculating the binding free energy using umbrella sampling at 300 K. The binding free energy calculated was $-54.5kcal\;mol^{-1}$, relatively similar to the binding energy of other amyloid fibrils. The simulation result suggests the thermodynamic properties of ${\beta}$-solenoid of HET-s prion and its similarity in dissociation pathways compared to amyloids.