Some Observations for Portfolio Management Applications of Modern Machine Learning Methods

Park, Jooyoung,Heo, Seongman,Kim, Taehwan,Park, Jeongho,Kim, Jaein,Park, Kyungwook Korean Institute of Intelligent Systems 2016 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.16 No.1

Recently, artificial intelligence has reached the level of top information technologies that will have significant influence over many aspects of our future lifestyles. In particular, in the fields of machine learning technologies for classification and decision-making, there have been a lot of research efforts for solving estimation and control problems that appear in the various kinds of portfolio management problems via data-driven approaches. Note that these modern data-driven approaches, which try to find solutions to the problems based on relevant empirical data rather than mathematical analyses, are useful particularly in practical application domains. In this paper, we consider some applications of modern data-driven machine learning methods for portfolio management problems. More precisely, we apply a simplified version of the sparse Gaussian process (GP) classification method for classifying users' sensitivity with respect to financial risk, and then present two portfolio management issues in which the GP application results can be useful. Experimental results show that the GP applications work well in handling simulated data sets.

Short-chain fatty acids inhibit the biofilm formation of Streptococcus gordonii through negative regulation of competence-stimulating peptide signaling pathway

Park Taehwan,Im Jintaek,Kim A Reum,Lee Dongwook,Jeong Sungho,Yun Cheol-Heui,Han Seung Hyun 한국미생물학회 2021 The journal of microbiology Vol.59 No.12

Streptococcus gordonii, a Gram-positive commensal bacterium, is an opportunistic pathogen closely related to initiation and progression of various oral diseases, such as periodontitis and dental caries. Its biofilm formation is linked with the development of such diseases by enhanced resistance against antimicrobial treatment or host immunity. In the present study, we investigated the effect of short-chain fatty acids (SCFAs) on the biofilm formation of S. gordonii. SCFAs, including sodium acetate (NaA), sodium propionate (NaP), and sodium butyrate (NaB), showed an effective inhibitory activity on the biofilm formation of S. gordonii without reduction in bacterial growth. SCFAs suppressed S. gordonii biofilm formation at early time points whereas SCFAs did not affect its preformed biofilm. A quorum-sensing system mediated by competence-stimulating peptide (CSP) is known to regulate biofilm formation of streptococci. Interestingly, SCFAs substantially decreased mRNA expression of comD and comE, which are CSP-sensor and its response regulator responsible for CSP pathway, respectively. Although S. gordonii biofilm formation was enhanced by exogenous synthetic CSP treatment, such effect was not observed in the presence of SCFAs. Collectively, these results suggest that SCFAs have an anti-biofilm activity on S. gordonii through inhibiting comD and comE expression which results in negative regulation of CSP quorum-sensing system. SCFAs could be an effective anti-biofilm agent against S. gordonii for the prevention of oral diseases.

Propionate Attenuates Growth of Oral Streptococci through Enhancing Methionine Biosynthesis

( Taehwan Park ),( Jintaek Im ),( A Reum Kim ),( Dongwook Lee ),( Sungho Jeong ),( Cheol-heui Yun ),( Seung Hyun Han ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.10

Oral streptococci are considered as an opportunistic pathogen associated with initiation and progression of various oral diseases. However, since the currently-available treatments often accompany adverse effects, alternative strategy is demanded to control streptococci. In the current study, we investigated whether short-chain fatty acids (SCFAs), including sodium acetate (NaA), sodium propionate (NaP), and sodium butyrate (NaB), can inhibit the growth of oral streptococci. Among the tested SCFAs, NaP most potently inhibited the growth of laboratory and clinically isolated strains of Streptococcus gordonii under anaerobic culture conditions. However, the growth inhibitory effect of NaP on six different species of other oral streptococci was different depending on their culture conditions. Metabolic changes such as alteration of methionine biosynthesis can affect bacterial growth. Indeed, NaP enhanced intracellular methionine levels of oral streptococci as well as the mRNA expression level of methionine biosynthesis-related genes. Collectively, these results suggest that NaP has an inhibitory effect on the growth of oral streptococci, which might be due to alteration of methionine biosynthesis. Thus, NaP can be used an effective bacteriostatic agent for the prevention of oral infectious diseases caused by oral streptococci.

Guidelines for Manufacturing and Application of Organoids: Brain

Taehwan Kwak,Si-Hyung Park,Siyoung Lee,Yujeong Shin,Ki-Jun Yoon,Seung-Woo Cho,Jong-Chan Park,Seung-Ho Yang,Heeyeong Cho,Heh-In Im,Sun-Ju Ahn,Woong Sun,Ji Hun Yang Korean Society for Stem Cell Research 2024 International journal of stem cells Vol.17 No.2

This study offers a comprehensive overview of brain organoids for researchers. It combines expert opinions with technical summaries on organoid definitions, characteristics, culture methods, and quality control. This approach aims to enhance the utilization of brain organoids in research. Brain organoids, as three-dimensional human cell models mimicking the nervous system, hold immense promise for studying the human brain. They offer advantages over traditional methods, replicating anatomical structures, physiological features, and complex neuronal networks. Additionally, brain organoids can model nervous system development and interactions between cell types and the microenvironment. By providing a foundation for utilizing the most human-relevant tissue models, this work empowers researchers to overcome limitations of two-dimensional cultures and conduct advanced disease modeling research.

Efficient Implementation of Simeck Family Block Cipher on 8-Bit Processor

Park, Taehwan,Seo, Hwajeong,Bae, Bongjin,Kim, Howon The Korea Institute of Information and Commucation 2016 Journal of information and communication convergen Vol.14 No.3

A lot of Internet of Things devices has resource-restricted environment, so it is difficult to implement the existing block ciphers such as AES, PRESENT. By this reason, there are lightweight block ciphers, such as SIMON, SPECK, and Simeck, support various block/key sizes. These lightweight block ciphers can support the security on the IoT devices. In this paper, we propose efficient implementation methods and performance results for the Simeck family block cipher proposed in CHES 2015 on an 8-bit ATmega128-based STK600 board. The proposed methods can be adapted in the 8-bit microprocessor environment such as Arduino series which are one of famous devices for IoT application. The optimized on-the-fly (OTF) speed is on average 14.42 times faster and the optimized OTF memory is 1.53 times smaller than those obtained in the previous research. The speed-optimized encryption and the memory-optimized encryption are on average 12.98 times faster and 1.3 times smaller than those obtained in the previous studies, respectively.

Secure Data Encryption for Cloud-Based Human Care Services

Park, Taehwan,Seo, Hwajeong,Lee, Sokjoon,Kim, Howon Hindawi Limited 2018 Journal of sensors Vol.2018 No.-

<P>Sensor network services utilize sensor data from low-end IoT devices of the types widely deployed over long distances. After the collection of sensor data, the data is delivered to the cloud server, which processes it to extract useful information. Given that the data may contain sensitive and private information, it should be encrypted and exchanged through the network to ensure integrity and confidentiality. Under these circumstances, a cloud server should provide high-speed data encryption without a loss of availability. In this paper, we propose efficient parallel implementations of Simeck family block ciphers on modern 64-bit Intel processors. In order to accelerate the performance, an adaptive encryption technique is also exploited for load balancing of the resulting big data. Finally, the proposed implementations achieved 3.5 cycles/byte and 4.6 cycles/byte for Simeck32/64 and Simeck64/128 encryption, respectively.</P>

A Study on the Effects of Project Developer’s Professionalism on the Project Development Performance: Focusing on the Mediating Effects of the PM Practice Competence and Development Firm’s Brand Authenticity

Taehwan Park(박태환),Sinbong Kang(강신봉) 한국신재생에너지학회 2022 한국신재생에너지학회 학술대회논문집 Vol.2022 No.4

Secure Message Transmission against Remote Control System

Park, Taehwan,Seo, Hwajeong,Bae, Bongjin,Kim, Howon The Korea Institute of Information and Commucation 2016 Journal of information and communication convergen Vol.14 No.4

A remote control system (RCS) can monitor a user's confidential information by using the broadcast receivers in Android OS. However, the current RCS detection methods are based only on a virus vaccine. Therefore, if the user's smartphone is infected by a brand new RCS, these methods cannot detect this new RCS immediately. In this paper, we present a secure message transmission medium. This medium is completely isolated from networks and can communicate securely through a QR code channel by using symmetric key cryptography such as the AES block cipher and public key cryptography such as elliptic curve cryptography for providing security. Therefore, the RCS cannot detect any confidential information. This approach is completely immune to any RCS attacks. Furthermore, we present a secure QR code-based key exchange protocol by using the elliptic curve Diffie-Hellman method and message transmission protocols; the proposed protocol has high usability and is very secure.

Efficient Parallel Implementation of Matrix Multiplication for Lattice-Based Cryptography on Modern ARM Processor

Park, Taehwan,Seo, Hwajeong,Kim, Junsub,Park, Haeryong,Kim, Howon Hindawi Limited 2018 Security and communication networks Vol.2018 No.-

<P>Recently, various types of postquantum cryptography algorithms have been proposed for the National Institute of Standards and Technology’s Postquantum Cryptography Standardization competition. Lattice-based cryptography, which is based on Learning with Errors, is based on matrix multiplication. A large-size matrix multiplication requires a long execution time for key generation, encryption, and decryption. In this paper, we propose an efficient parallel implementation of matrix multiplication and vector addition with matrix transpose using ARM NEON instructions on ARM Cortex-A platforms. The proposed method achieves performance enhancements of 36.93%, 6.95%, 32.92%, and 7.66%. The optimized method is applied to the Lizard. CCA key generation step enhances the performance by 7.04%, 3.66%, 7.57%, and 9.32% over previous state-of-the-art implementations.</P>

SNS(Social Network Services) 내에서 정보보안 지식공유의도에 미치는 영향 요인

박태환(Taehwan Park),김수환(Suhwan Kim),장재영(Jaeyoung Jang) 한국전자거래학회 2015 한국전자거래학회지 Vol.20 No.1

최근 IT 산업의 급격한 성장과 스마트폰의 출현으로 인해, 우리는 시와 장소를 가리지 않고 인터넷 환경에 접속할 수 있게 되었다. 하지만, 이로 인한 부정적인 영향도 발생하였다. 그중 하나는 피싱(Phishing), 스미싱(SMishing)과 같은 금융 범죄의 증가이다. 피싱, 스미싱과 같은 범죄로부터 이용자를 보호하기 위한 많은 연구들이 진행 중에 있지만, SNS에서의 보안 관련 지식공유를 통한 범죄 완화에 대한 연구는 현재 찾아보기 어려운 실정이다. 본 연구에서는, SNS 이용자가 보안 관련 지식공유 의도를 불러일으키는 영향 요인에는 무엇이 있는지 알아보고자 한다. 연구를 통해 다음을 알 수 있었다. 지식제공 자기효능감은 자기표현에 유의미한 영향을 미친다. 그리고 자기표현, 정보보안 의식, 소속감은 SNS 내에서 보안 관련 지식공유 의도에 유의미한 영향을 미치는 것으로 밝혀졌다. 반면에, 이타성은 SNS내에서 보안 관련 지식공유 의도에 유의미한 영향을 미치지 않았다. 향후에는 본 연구를 토대로, SNS 뿐만 아니라 모든 형태의 온라인 공동체로 연구의 범위를 넓혀, 가설을 일반화시키려는 노력이 필요할 것으로 보인다. Due to recent growth in IT industry along with the expansion of smartphone, we came to connect to the Internet wherever and whenever we are. However, this causes negative side effects, though. One of them is a rapid increase of the financial crimes such as the Phishing and the SMishing. There have been many on-going researches about crimes such as Phishing and SMishing to protect users. However, the study about sharing knowledge on SNS to prevent such a crime can be hardly found. Based on social identity theory, we conduct the research about factors on SNS users’ intention to share the information security knowledge on SNS. As a result, we found that knowledge provision self-efficacy has a significant impact on self-expression. In addition, it also found out self-expression, awareness about information security and the sense of belonging have a significant impact respectively on the intention to share the information security knowledge on SNS. On the other hand, the altruism didn’t have a significant impact to the intention to share information security knowledge on SNS. With this research as a starting point, it seems necessary to expand its range to all types of online community in the future for the generalization of the hypotheses.