A parameterized model to select discriminating features on keystroke dynamics authentication on smartphones

Lee, Hyungu,Hwang, Jung Yeon,Lee, Shincheol,Kim, Dong In,Lee, Sung-Hoon,Lee, Jaehwan,Shin, Ji Sun Elsevier 2019 Pervasive and mobile computing Vol.54 No.-

<P><B>Abstract</B></P> <P>Nowadays, smartphones work not only as personal devices, but also as distributed IoT edge devices uploading information to a cloud. Their secure authentications become more crucial as information from them can spread wider. Keystroke dynamics is one of prominent candidates for authentications factors. Combined with PIN/pattern authentications, keystroke dynamics provide a user-friendly multi-factor authentication for smartphones and other IoT devices equipped with keypads and touch screens. There have been many studies and researches on keystroke dynamics authentication with various features and machine-learning classification methods. However, most of researches extract the same features for the entire user and the features used to learn and authenticate the user’s keystroke dynamics pattern. Since the same feature is used for all users, it may include features that express the users’ keystroke dynamics well and those that do not. The authentication performance may be deteriorated because only the discriminative feature capable of expressing the keystroke dynamics pattern of the user is not selected. In this paper, we propose a parameterized model that can select the most discriminating features for each user. The proposed technique can select feature types that better represent the user’s keystroke dynamics pattern using only the normal user’s collected samples. In addition, performance evaluation in previous studies focuses on average EER(equal error rate) for all users. EER is the value at the midpoint between the FAR(false acceptance rate) and FRR(false rejection rate), FAR is the measure of security, and FRR is the measure of usability. The lower the FAR, the higher the authentication strength of keystroke dynamics. Therefore, the performance evaluation is based on the FAR. Experimental results show that the FRR of the proposed scheme is improved by at least 10.791% from the maximum of 31.221% compared with the other schemes.</P>

글루탐산 생산을 위한 Lactococcus lactis HY7803 균주의 대두 발효 적용

Lee Jungmin,Heo Sojeong,Choi Jihoon,Pyo Eunji,Lee Myounghee,Shin Sangick,Lee Jaehwan,Lee Junglyoul,정도원 한국미생물·생명공학회 2023 한국미생물·생명공학회지 Vol.51 No.1

The glutamic acid producing strain for development savory taste enhancing foods was identified the possibility through application into soybean fermentation. To check the effects on glutamic acid production during soybean fermentation, Lactococcus lactis HY7803 was introduced as a starter. The soybean samples were analyzed on days 0, 7, 14 and 21. The numbers of bacteria decreased gradually, while the content of amino-type nitrogen increased during fermentation in the soybean with L. lactis HY7803. Glutamic acid content in soybeans with L. lactis HY7803 increased from 114.99 ± 9.37 pmol/ul on day 0 to 138.14 ± 1.76 pmol/ul on day 21, showing an overall higher amino acid content than soybeans without L. lactis HY7803 and similar content to soybeans with Aspergillus oryzae SNU-G. It was clearly distinguished through principal component analysis. Consequently, our results indicate that L. lactis HY7803 is available as a fungus replacement and may be a good starter strain for enhancing savory taste in vitro as well as soybean fermentation.

Development of an Intelligent Active Trailing-edge Flap Rotor to Reduce Vibratory Loads in Helicopter

Jaehwan Lee(이재환),최재혁,SangJoon Shin(신상준) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.4

일반적으로 헬리콥터는 양력, 추력 그리고 힘을 발생시키기 위해 로터 시스템을 사용하기 때문에 공력환경이 매우 복잡하다. 블레이드 와류 간섭과 같은 비정상 공력 환경이 발생한다. 이러한 비정상 공력 환경은 진동하중과 높은 공력소음을 유발한다. 진동하중과 공력소음은 로터 블레이드 회전수에 N 배의 해당하는 주파수 (N/rev)를 갖는다. 하지만 스와시 판과 피치링크로 이루어진 전통적인 로터 조종계통은 블레이드가 1 회 회전하는 동안 한번의 조종 변위를 발생시킬 수 있기 때문에 그러한 진동하중을 조절하기에는 한계가 있다. 이러한 문제를 해결하기 위해 많은 능동 제어 기법들이 개발되었다. 능동 제어기법은 임의의 주파수로 블레이드의 피치 각을 조종할 수 있다. 본 논문에서는 비정상 공력 하중을 변화시키기 위해 능동 제어기법 중 한 가지인 능동 뒷전 플랩 블레이드의 설계를 수행하였다. 능동 뒷전 플랩 블레이드는 에어포일의 캠버를 변화시키기 위해 작동기에 의해 구동되는 뒷전 플랩을 장착한다. 뒷전 플랩을 작동시키기 위해 블레이드 내부에 위치 압전 작동기를 사용하였다. Helicopter uses a rotor system to generate lift, thrust and forces, and its aerodynamic environment is generally complex. Unsteady aerodynamic environment arises such as blade vortex interaction. This unsteady aerodynamic environment induces vibratory aerodynamic loads and high aeroacoustic noise. Those are at N times the rotor blade revolutions (N/rev). But conventional rotor control system composed of pitch links and swash plate is not capable of adjusting such vibratory loads because its control is restricted to 1/rev. Many active control methodologies have been examined to alleviate the problem. The blade using active control device manipulates the blade pitch angle at arbitrary frequencies. In this paper, Active Trailing-edge Flap blade, which is one of the active control methods, is designed to modify the unsteady aerodynamic loads. Active Trailing-edge Flap blade uses a trailing edge flap manipulated by an actuator to change camber of the airfoil. Piezoelectric actuators are installed inside the blade to manipulate the trailing edge flap.

3D Cross-Linked Nanoweb Architecture of Binder-Free TiO₂ Electrodes for Lithium Ion Batteries

Lee, Sangkyu,Ha, Jaehwan,Choi, Junghyun,Song, Taeseup,Lee, Jung Woo,Paik, Ungyu American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.22

<P>The nanoweb structure of TiO<SUB>2</SUB> anode, cross-linked between electrospun nanofibers, is directly fabricated on the current collector by utilizing the fluidity of low glass transition temperature polymer, poly(vinyl acetate), at room temperature. This characteristic enables us to fabricate the nanoweb structure by direct electrospinning on the current collector, followed by uniaxial pressing. This proposed structure facilitates electron transport through the direct conducting pathways between TiO<SUB>2</SUB> active materials and current collector as well as provides strong adhesion strength to the current collector without polymeric binders. Consequently, we could achieve stable cycle performance up to 100 cycles and the excellent rate capability of ∼60% at high rate charge/discharge condition of 10 <I>C</I>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-22/am404082h/production/images/medium/am-2013-04082h_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am404082h'>ACS Electronic Supporting Info</A></P>

Oxidative stability of extracts from red ginseng and puffed red ginseng in bulk oil or oil-in-water emulsion matrix

Lee, Sang-Jun,Oh, Sumi,Kim, Mi-Ja,Sim, Gun-Sub,Moon, Tae Wha,Lee, JaeHwan The Korean Society of Ginseng 2018 Journal of Ginseng Research Vol.42 No.3

Background: Explosive puffing can induce changes in the chemical, nutritional, and sensory quality of red ginseng. The antioxidant properties of ethanolic extracts of red ginseng and puffed red ginseng were determined in bulk oil and oil-in-water (O/W) emulsions. Methods: Bulk oils were heated at $60^{\circ}C$ and $100^{\circ}C$ and O/W emulsions were treated under riboflavin photosensitization. In vitro antioxidant assays, including 2,2-diphenyl-1-picrylhudrazyl, 2,2'-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid, ferric reducing antioxidant power, total phenolic content, and total flavonoid content, were also performed. Results: The total ginsenoside contents of ethanolic extract from red ginseng and puffed red ginseng were 42.33 mg/g and 49.22 mg/g, respectively. All results from above in vitro antioxidant assays revealed that extracts of puffed red ginseng had significantly higher antioxidant capacities than those of red ginseng (p < 0.05). Generally, extracts of puffed red and red ginseng had high antioxidant properties in riboflavin photosensitized O/W emulsions. However, in bulk oil systems, extracts of puffed red and red ginseng inhibited or accelerated rates of lipid oxidation, depending on treatment temperature and the type of assay used. Conclusion: Although ethanolic extracts of puffed red ginseng showed stronger antioxidant capacities than those of red ginseng when in vitro assays were used, more pro-oxidant properties were observed in bulk oils and O/W emulsions.

An Empirical Performance Analysis on Hadoop via Optimizing the Network Heartbeat Period

( Jaehwan Lee ),( June Choi ),( Hongchan Roh ),( Ji Sun Shin ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.11

To support a large-scale Hadoop cluster, Hadoop heartbeat messages are designed to deliver the significant messages, including task scheduling and completion messages, via piggybacking to reduce the number of messages received by the NameNode. Although Hadoop is designed and optimized for high-throughput computing via batch processing, the real-time processing of large amounts of data in Hadoop is increasingly important. This paper evaluates Hadoop’s performance and costs when the heartbeat period is controlled to support latency sensitive applications. Through an empirical study based on Hadoop 2.0 (YARN) [1] architecture, we improve Hadoop’s I/O performance as well as application performance by up to 13 percent compared to the default configuration. We offer a guideline that predicts the performance, costs and limitations of the total system by controlling the heartbeat period using simple equations. We show that Hive performance can be improved by tuning Hadoop’s heartbeat periods through extensive experiments.

Comfort Driving Cold/Warm Thermos Food Cart

Jaehwan Lee(이재환) 한국디자인학회 2018 한국디자인학회 국제초대전도록 Vol.2018 No.6

The Research Approaches for Food Industry and Technology Transfer

JaeHwan Lee 한국식품영양과학회 2019 한국식품영양과학회 학술대회발표집 Vol.2019 No.10

Outboard Diesel Engine

Jaehwan Lee(이재환) 한국디자인학회 2019 한국디자인학회 국제초대전도록 Vol.2019 No.11

Efficient Heterogeneous Network-Routing Method Based on Dynamic Control Middleware for Cyber-Physical System

Lee, Hyungsoo,Lee, Jaehwan,Nam, Sanghyuck,Park, Sangoh Hindawi Limited 2018 Journal of sensors Vol.2018 No.-

<P>A cyber-physical system depends on stable control and interaction between the many systems and devices connected to the network. Dynamic control middleware, which considers the characteristics of a cyber-physical system, supports the dynamic search and control of devices existing on the global network using Internet protocol version 6 (IPv6). However, systems and devices may connect to a network using a variety of heterogeneous protocols, not just IPv6. To solve the problem of heterogeneous protocols, this paper proposes a routing technique which enables network devices to communicate using different protocols. The proposed network-routing module can register devices with various protocols and improve the stability of the efficient heterogeneous network.</P>