Modelling Stock Market Volatility: Evidence from Vietnam

Ho,Thuy Tien,Ho,Thu Hoai,Ngo,Van Toan 한국유통과학회 2019 KODISA ICBE (International Conference on Business Vol.2019 No.-

This study empirically investigates the volatility pattern of Indian stock market based on time series data which consists of daily closing prices of VN-Index for period 2005 - 2016. The analysis has been done using both symmetric and asymmetric models of Generalized Autoregressive Conditional Heteroscedastic (GARCH). According to Akaike Information Criterion (AIC) and Schwarz Information Criterion (SIC) criteria, the study proves that GARCH (1,1) and TGARCH (1,1) estimations are found to be most appropriate model to capture the symmetric and asymmetric volatility respectively. The study also provides evidence for the existence of asymmetric effects (leverage) by the parameters of the EGARCH(1,1) model that show that negative shocks have significant effects on Conditionally (fluctuate), but in the TGARCH(1.1) model the results are not as expected. This topic also provides investors with a tool to forecast the return of the stock market. At the same time, the results of the study will help investors and policymakers determine the profitability and volatility of the market so that they make the right decision to hold the securities.

Body and Nature: Feminist ecological consciousness in Ho Xuan Huong's Sino- Nom poetry-

호카인반(Ho Khanh Van) 열상고전연구회 2022 열상고전연구 Vol.77 No.-

Ho Xuan Huong is a unique and outstanding Vietnamese female literary phenomenon in medieval time. Her famous poems have attracted the attention of readers and literary researchers all over the world. At the beginning of the twentieth century, the female poet Ho Xuan Huong received a lot of attention from Vietnamese scholars. This paper approaches Ho Xuan Huong’s poetry from perspective of ecofeminism, based on two elements: body and nature. Poetry of Ho Xuan Huong was thoughtfully and profoundly written with “green consciousness” and “green poetic” Christ Barrett (2018), Early Modern English Literature and the Poetics of Cartographic Anxiety, Oxford University Press, p.107. . Firstly, female body was reflected with nature and through nature. Female body is nature and nature is the embodiment of female body. Human and nature are the one and the same in her viewpoint. Moreover, nature is also the sexual desire and expression of human sexuality. Secondly, through the reflection of nature, Ho Xuan Huong expressed a strong voice which protesting against the strict and old-fashioned values ​​of male authority oppressed and dominated women. Nature is a sign that expresses the bodily value of a woman and her desire of freedom. Thirdly, the ecological feminist spirit of Ho Xuan Huong is not only expressed through ideology but also manifested in poetic language. She wrote in “green language” Thomas H. Ford (2018), Wordsworth and the Poetics of Air – Atmospheric Romanticism in a Time of Climate Change, Cambridge University Press, p.6. : the language of nature, of a strong, innocent natural life. Liberal life, associated with the nature of the agricultural community; traditional beliefs such as Lingaism, the worship of Mother Goddesses Ngo Đuc Thinh (2010), Vietnamese Mother Goddesses, Relious Publishing House, Ha Noi, p. 21. and personal creativity of Ho Xuan Huong are important factors forming feminist ecological consciousness in the precious heritage of “the Queen of Nom poetry” 호춘향(胡春香, Ho Xuan Huong)은 베트남 중세문학사에서 개성적인 여성 작가 중 한 명이다. 그녀의 시는 전 세계의 독자와 문학 연구자들의 관심을 끌고 있다. 이 글에서는 에코페미니즘 비평의 관점에서 호춘향의 시에 접근하고자 한다. 호춘향의 시에 나타난 생태학적 인식은 대담하고 강력해 보인다. 첫째, 인간의 몸, 특히 여성의 몸은 자연에 의해 재현되며 자연과 같은 것으로 드러난다. 사람의 몸은 자연이며 자연은 인체의 화신이다. 그녀의 눈에는 인간과 자연이 별개의 존재가 아니라 하나이다. 또한 자연을 통해 인간의 욕망과 애욕을 표현하고 있다. 둘째, 호춘향은 자연의 재현을 통해 여성을 억압하고 지배하는 가혹한 가부장제에 대한 저항을 보여준다. 자연은 여성 몸의 가치, 생명권과 성적 자유를 성취하고자 하는 욕망을 표현하는 대상이다. 셋째, 호춘향의 에코페미니즘적 주제의식은 사상뿐만 아니라 그녀의 시에 나타난 표현을 통해 확인할 수 있다. 호춘향의 시에서는 자연과 가까운 농업 생활, 다산의 신념, 모성 신앙, 그리고 자유 지향 의식, 봉건주의에서 벗어나고자 하는 의식이 나타난다. 에코페미니즘 의식은 ‘쯔놈(chu Nom)시의 여왕’이라 불리는 그녀의 작품을 형성하는 데 중요한 요소라고 할 수 있다.

Atomically thin p–n junctions with van der Waals heterointerfaces

Lee, Chul-Ho,Lee, Gwan-Hyoung,van der Zande, Arend M.,Chen, Wenchao,Li, Yilei,Han, Minyong,Cui, Xu,Arefe, Ghidewon,Nuckolls, Colin,Heinz, Tony F.,Guo, Jing,Hone, James,Kim, Philip Nature Publishing Group, a division of Macmillan P 2014 Nature nanotechnology Vol.9 No.9

Semiconductor p–n junctions are essential building blocks for electronic and optoelectronic devices. In conventional p–n junctions, regions depleted of free charge carriers form on either side of the junction, generating built-in potentials associated with uncompensated dopant atoms. Carrier transport across the junction occurs by diffusion and drift processes influenced by the spatial extent of this depletion region. With the advent of atomically thin van der Waals materials and their heterostructures, it is now possible to realize a p–n junction at the ultimate thickness limit. Van der Waals junctions composed of p- and n-type semiconductors—each just one unit cell thick—are predicted to exhibit completely different charge transport characteristics than bulk heterojunctions. Here, we report the characterization of the electronic and optoelectronic properties of atomically thin p–n heterojunctions fabricated using van der Waals assembly of transition-metal dichalcogenides. We observe gate-tunable diode-like current rectification and a photovoltaic response across the p–n interface. We find that the tunnelling-assisted interlayer recombination of the majority carriers is responsible for the tunability of the electronic and optoelectronic processes. Sandwiching an atomic p–n junction between graphene layers enhances the collection of the photoexcited carriers. The atomically scaled van der Waals p–n heterostructures presented here constitute the ultimate functional unit for nanoscale electronic and optoelectronic devices.

Analyzing Customer Experience in Hotel Services Using Topic Modeling

( Van-ho Nguyen ),( Thanh Ho ) 한국정보처리학회 2021 Journal of information processing systems Vol.17 No.3

Nowadays, users’ reviews and feedback on e-commerce sites stored in text create a huge source of information for analyzing customers’ experience with goods and services provided by a business. In other words, collecting and analyzing this information is necessary to better understand customer needs. In this study, we first collected a corpus with 99,322 customers’ comments and opinions in English. From this corpus we chose the best number of topics (K) using Perplexity and Coherence Score measurements as the input parameters for the model. Finally, we conducted an experiment using the latent Dirichlet allocation (LDA) topic model with K coefficients to explore the topic. The model results found hidden topics and keyword sets with high probability that are interesting to users. The application of empirical results from the model will support decision-making to help businesses improve products and services as well as business management and development in the field of hotel services.

Underlay Cooperative Cognitive Networks with Imperfect Nakagami-m Fading Channel Information and Strict Transmit Power Constraint: Interference Statistics and Outage Probability Analysis

Ho-Van, Khuong,Sofotasios, Paschalis C.,Freear, Steven The Korea Institute of Information and Commucation 2014 Journal of communications and networks Vol.16 No.1

This work investigates two important performance metrics of underlay cooperative cognitive radio (CR) networks: Interference cumulative distribution function of licensed users and outage probability of unlicensed users. These metrics are thoroughly analyzed in realistic operating conditions such as imperfect fading channel information and strict transmit power constraint, which satisfies interference power constraint and maximum transmit power constraint, over Nakagami-m fading channels. Novel closed-form expressions are derived and subsequently validated extensively through comparisons with respective results from computer simulations. The proposed expressions are rather long but straightforward to handle both analytically and numerically since they are expressed in terms of well known built-in functions. In addition, the offered results provide the following technical insights: i) Channel information imperfection degrades considerably the performance of both unlicensed network in terms of OP and licensed network in terms of interference levels; ii) underlay cooperative CR networks experience the outage saturation phenomenon; iii) the probability that the interference power constraint is satisfied is relatively low and depends significantly on the corresponding fading severity conditions as well as the channel estimation quality; iv) there exists a critical performance trade-off between unlicensed and licensed networks.

LLR 을 적용한 복호 후 협력 통신 프로토콜 무선 네트워크에 관한 연구

( Ho Van Khuong ),공형윤 ( Hyung-yun Kong ),이동운 ( Dongun Lee ),남두희 ( Doohee Nam ) 한국정보처리학회 2005 한국정보처리학회 학술대회논문집 Vol.12 No.2

복호 후 전달 협력 통신 프로토콜(DFP: Decode-and-Forward Cooperative Communication Protocol)은 물리적인 안테나의 증가 없이 다중 안테나 시스템의 장점을 가지는 통신 방법이다. 지금까지는 신호 대 잡음 비율(SNR: Signal to Noise Ratio)이나 경로이득 크기의 루트를 취한 값들을 이용하여 중계노드에서 복호한 데이터를 전달 여부를 결정하여 중계 노드에서 부정확한 검파가 되지 않도록 방지하였다. 본 논문에서는 기존의 DFP 에서 사용되던 SNR 을 대체할 수 있는 LLR(Log-Likelihood Ratio)를 이용하는 방법을 제안하였다. 레일리 페이딩 환경과 AWGN 환경에서 기준값이나 중계 노드의 위치에 상관없이 LLR 기반의 DFP 가 SNR 기반의 DFP 보다 높은 성능을 보이는 것을 확인하였다.

Synthesis of Metallosupramolecular Nanocages through the Assembly of Triple-Stranded Helicates

( HO VAN MINH HAI ),( MAI DUY HIEN ),유효종 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.1

Comparison between Water and N-Tetradecane as Insulation Materials through Modeling and Simulation of Heat Transfer in Packaging Box for Vaccine Shipping

Van-Duong Dao,Ik-Kyu Jin,Ho Hur,Ho-Suk Choi 한국청정기술학회 2016 청정기술 Vol.22 No.1

This study reports on the modeling and simulation of heat transfer in packaging boxes used for vaccine shipping. Both water and n-tetradecane are used as primary insulation materials inside a multi-slab system. The one-dimensional model, which is a spherical model using a radius equivalent to the rectangular geometry of container, is applied in this study. N-tetradecane with low thermal diffusivity and proper phase transition temperature exhibits higher heat transfer resistance during both heating and cooling processes compared to water. Thus, n-tetradecane is a better candidate as an insulating material for packaging containers for vaccine shipping. Furthermore, the developed method can also become a rapid and economic tool for screening appropriate phase change materials used as insulation materials with suitable properties in logistics applications.

Chemical constituents from Vietnamese mangrove <i>Calophyllum inophyllum</i> and their anti-inflammatory effects

Van Thanh, Nguyen,Jang, Hyun-Jae,Vinh, Le Ba,Linh, Kieu Thi Phuong,Huong, Phan Thi Thanh,Cuong, Nguyen Xuan,Nam, Nguyen Hoai,Van Minh, Chau,Kim, Young Ho,Yang, Seo Young Elsevier 2019 Bioorganic chemistry Vol.88 No.-

<P><B>Abstract</B></P> <P>In a search for anti-inflammatory activity in resources from Vietnamese mangroves, we found that a methanolic extract from the leaves of <I>Calophyllum inophyllum</I> (CIL) showed significant anti-inflammatory effects <I>in vitro</I>. Using various chromatographic techniques, we subsequently isolated 12 compounds (<B>1</B>–<B>12</B>) from a methanolic extract of CIL, including two novel compounds (<B>1</B>–<B>2</B>). The inhibitory effects of these compounds on lipopolysaccharide-induced nitric oxide (NO) production in RAW264.7 cells were also evaluated. Compound <B>1</B> significantly suppressed NO production (IC<SUB>50</SUB> = 2.44 ± 0.88 µM), the secretion of pro-inflammatory cytokines (including interleukin-1 beta and tumor necrosis factor alpha), and the expression of inducible nitric oxide synthase through downregulation of nuclear factor-kappa-B signaling cascades. These results suggest that <I>C. inophyllum</I> leaves might be a useful resource for the development of drugs for the treatment of inflammation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Twelve compounds were isolated from Vietnamese mangrove <I>Calophyllum inophyllum</I>. </LI> <LI> Two new compounds <B>1</B> and <B>2</B> were determined by spectroscopic methods. </LI> <LI> Compound <B>1</B> showed significant anti-inflammatory activity. </LI> <LI> These results suggested that <I>C. inophyllum</I> might useful as the anti-inflammation drug. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A high-frequency and high-power quasi-class-E amplifier design using a finite bias feed inductor

Van, Ju-Ho,Kim, Min-Su,Jung, Sung-Chan,Park, Hyun-Chul,Ahn, Gunhyun,Park, Cheon-Seok,Kim, Byung-Sung,Yang, Youngoo Wiley Subscription Services, Inc., A Wiley Company 2007 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.49 No.5

<P>This paper presents a design method for a compact high-efficiency quasi-class-E amplifier, using a finite bias feed inductor. It is very difficult to achieve proper class-E operation from high-power transistors operating in the high-frequency region because of their internal parasitic components. To mitigate the effects of internal parasitic components on class-E operation, a finite DC feed inductance is introduced to resonate out the capacitive parasitic components. A quasi-class-E amplifier with a finite DC feed inductor was designed and implemented at 1.2 GHz using a high-power laterally diffused metal-oxide-semiconductor field-effect transistor (LDMOSFET). We compared simulated time domain current and voltage waveforms with ideal ones. As the test results indicated, power-added efficiency as high as 70.4% was achieved, at high output power of 39.55 dBm, without losing the circuits' simplicity, one of the most important advantages of class-E operation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1114–1118, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22368</P>