• Journal of the Society of Naval Architects of Korea
• /
• v.34 no.3
• /
• pp.70-75
• /
• 1997

This paper concerns with a safe and efficient transportation method of hot-coils on cargo ship. An automatic loading and unloading system of hot-coils by cassettes, which secure the geometrically unstable cargo, hot-coil, by supporting with wedges on both sides, is considered efficient and profitable. Safety of hot-coil on cassette and subsequently safety of total cargo ship are directly affected by the wedge angle of cassette. For optimal design of the cassette wedge angle, a dynamic model of hot-coil/cassette cargo is developed with constraint of no relative motions between the coil and the cassette. Force equilibrium conditions between resultant alternating inertia forces on hot-coil due to motions of cargo ship in waves and reactions forces from cassette wedge surfaces are derived and consequently a numerical simulation code is implemented. Cassette wedge angle of 37 degree is taken as optimal by considering dynamic stability of hot-coil and strength of cassette structure. Performance of the designed cassette wedge angle is investigated by scaled bench test.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.1
• /
• pp.110-115
• /
• 2006

STSAT-2 is the first satellite which will be launched by the first Korean Space Launch Vehicle(KSLV). Ground station Baseband Control system(GBC) is now developed for STSAT-2. GBC has two functions. One is control data path between satellite control computers and ground station antennas(1.5M, 3.7M, 13M) automatically. The other is sending and receiving data between ground station and satellite. GBC is implemented by FPGA(Field-Programmable Gate Array) which includes almost all logic(for MODEM, PROTOCOL and GBC system control). MODEM in GBC has two uplink FSK modulators(1.2[kbps], 9.6[kbps]) and six downlink FSK demodulators(9.6[kbps], 38.4[kbps]). In hardware, STSAT-2 GBC is smaller than STSAT-1 GBC. In function, STSAT-2 GBC has more features than STSAT-1 GBC. This paper is about GBC structure, functions and test results.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.4
• /
• pp.1892-1903
• /
• 2016

Mobile social network is becoming more and more popular with respect to the development and popularity of mobile devices and interpersonal sociality. As the amount of social data increases in a great deal and cloud computing techniques become developed, the architecture of mobile social network is evolved into cloud-based that mobile clients send data to the cloud and make data accessible from clients. The data in the cloud should be stored in a secure fashion to protect user privacy and restrict data sharing defined by users. Ciphertext-policy attribute-based encryption (CP-ABE) is currently considered to be a promising security solution for cloud-based mobile social network to encrypt the sensitive data. However, its ciphertext size and decryption time grow linearly with the attribute numbers in the access structure. In order to reduce the computing overhead held by the mobile devices, in this paper we propose a new Outsourcing decryption and Match-then-decrypt CP-ABE algorithm (OM-CP-ABE) which firstly outsources the computation-intensive bilinear pairing operations to a proxy, and secondly performs the decryption test on the attributes set matching access policy in ciphertexts. The experimental performance assessments show the security strength and efficiency of the proposed solution in terms of computation, communication, and storage. Also, our construction is proven to be replayable choosen-ciphertext attacks (RCCA) secure based on the decisional bilinear Diffie-Hellman (DBDH) assumption in the standard model.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.12
• /
• pp.59-73
• /
• 2017

Numerical analysis using 3D finite element program (PLAXIS 3D) evaluated the interaction of soil - pile structure under dynamic surface loading. The dynamic p-y curve of the 1-g shaking table experiment by numerical analysis was calculated, and the parametric studies were presented by considering the pile-soil condition, the pile tip condition, and the loading condition. The frequency of 1.4 Hz is almost equal to the natural frequency of the pile - soil system. The p and y values of resonance phenomenon are significantly different from the results of other frequencies. The results can be summarized by a third order polynomial function representing the trend line in the p-y curve. In the case of a single pile, the shape of the dominant curve was found to be an ellipse by mathematical proof. The elliptic equation can be used for the dynamic design or analysis of soil-pile system.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.8
• /
• pp.9-21
• /
• 2020

With the proliferation of RDF knowledge graphs(KGs), there arose a need of a standardized schema representation of the graph model for effective data interchangeability and interoperability. The need resulted in the development of SHACL specification to describe and validate RDF graph's structure by W3C. Relational databases(RDBs) are one of major sources for acquiring structured knowledge. The standard for automatic generation of RDF KGs from RDBs is R2RML, which is also developed by W3C. Since R2RML is designed to generate only RDF data graphs from RDBs, additional manual tasks are required to create the schemas for the graphs. In this paper we propose an approach to automatically generate SHACL schemas for RDF KGs populated by R2RML mappings. The key of our approach is that the SHACL shemas are built only from R2RML documents. We describe an implementation of our appraoch. Then, we show the validity of our approach with R2RML test cases designed by W3C.

• Structural Engineering and Mechanics
• /
• v.31 no.5
• /
• pp.507-526
• /
• 2009

Based on numerical and experimental methods, a systematic structural evaluation of a steel natatorium in service was carried out in detail in this paper. Planning of inspection tasks was proposed firstly according to some national codes in China in order to obtain the economic and reliable results. The field visual inspections and static computation were conducted in turn under in-service environmental conditions. Further a three-dimensional finite element model was developed according to its factual geometry properties obtained from the field inspection. An analytical modal analysis was performed to provide the analytical modal properties. The field vibration tests on the natatorium were conducted and then two different system identification methods were used to obtain the dynamic characteristics of the natatorium. A good correlation was achieved in results obtained from the two system identification methods and the finite element method (FEM). The numerical and experimental results demonstrated that the main structure of the natatorium in its present status is safe and it still satisfies the demand of the national codes in China. But the roof system such as purlines and skeletons must be removed and rebuilt completely. Moreover the system identification results showed that field vibration test is sufficient to identify the reliable dynamic properties of the natatorium. The constructive suggestion on structural evaluation of the natatorium is that periodic assessment work must be maintained to ensure the natatorium's safety in the future.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.35 no.3
• /
• pp.87-94
• /
• 2012

This study investigates the relationship among locus of control, organizational justice, and job satisfaction. First, this study examines the conceptual structures of organizational justice through field study. Second, organizational justice influences job satisfaction. Third, locus of control influences organizational justice. Literature review identified four factors of organizational justice - distributive, procedural, interpersonal, and informational justice. These identified determinants are expected to have significant relationships with locus of control and job satisfaction. Questionnaires were distributed to 500 members of a manufacturing companies. Among returned questionnaires, 357 samples were used for empirical study. Structural equation analyses based on PLS (partial least square) method were employed to test the hypotheses and the model. The overall adequacy of fit was found to be acceptable. Confirmatory factor analyses supported a 4-factor structure of organizational justice. Distributive, procedural, interpersonal, and informational justice had significant positive effects on job satisfaction. In addition, the effects of locus of control had significant positive effects on organizational justice factors. The results of this study suggest that interpersonal and informational justice should be regarded as important factors of organizational justice to analyze the relationships between locus of control and job satisfaction as well as the relationships among the justice constructs.

• The Journal of the Korea Contents Association
• /
• v.16 no.12
• /
• pp.724-734
• /
• 2016

The purpose of this study was to retire attitude of journalists verify the mediating effect of impact and satisfaction of life in old age, and prepare, perform and enhance the retirement attitudes of journalists to suggest journalists welfare policies and practices preparing for retirement. Surveyed a total of 233 additional analysis was used to journalists working in Gwangju, Jeonnam media. We used the SPSS 18.0 and 20.0 AMOS program to derive a result, a factor analysis was performed with reliability test for the variables, the model was subjected to structure analysis for the hypothesis testing. The results were the retirement attitudes of journalists had a significant impact on satisfaction with life in retirement preparation, retirement preparation had significant influence on life satisfaction. In addition, the journalists were retired through the mediating effect of attitudes that are ready to maximize retirement life satisfaction. Based on such findings, we propose a practical. Policy implications that can enhance the retirement attitudes and preparation for retirement journalists.

• Journal of the Korean institute of surface engineering
• /
• v.43 no.1
• /
• pp.25-30
• /
• 2010

Titanium and titanium alloys are widely used for orthopedic and dental implants for their superior mechanical properties, low modulus, excellent corrosion resistance and good biocompatibility. In this study, corrosion behaviors of nanotube formed on the bone plate of Ti-6Al-4V alloy for dental use have been investigated. $TiO_2$ nanotubes were formed on the dental bone plates by anodization in $H_3PO_4$ containing 0.6 wt % NaF solution at $25^{\circ}C$. Electrochemical experiments were performed using a conventional three-electrode configuration with a platinum counter electrode and a saturated calomel reference electrode. Anodization was carried out using a scanning potentiostat (EG&G Co, Model 263A USA), and all experiments were conducted at room temperature. The surface morphology was observed using field emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy(EDS). The corrosion behavior of the dental bone plates was examined using potentiodynamic test(potential range of -1500~2000 mV) in a 0.9% NaCl solution by potentiostat (EG&G Co, PARSTAT 2273. USA). The inner diameter of nanotube was about 150~180 nm with wall thickness of about 20 nm. The interspace of nanotube to nanotube was 50 nm. The passive region of the nanotube formed bone plates showed the broad range compared to non-nanotube formed bone plates. The corrosion surface of sample was covered with corrosion products.

• Journal of Korea Game Society
• /
• v.9 no.3
• /
• pp.87-96
• /
• 2009

According to the Flow Theory, when the perceived level of Challenges of player and his skill are high, he is able to experience the flow state. What does the skill mean in the Flow Theory? This study suggests that the self-efficacy of the actor should be concerned to understand the perceived level of actor's skill in relation to the level of Challenges and his personal characteristics. This study hypothesizes the equity-distribution of extrinsic reward and the positive reputation influence the player's self-efficacy, and his self-efficacy affect the flow experience. This hypothesis is confirmed by the structure equation model test. This result can serve to understand skill related on the flow theory, and what factors players to get flow experience are given by.