• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.518-519
• /
• 2006

A connection between pulse-periodical laser radiation power and stability of liquid-metal contacts between powder particles during selective laser sintering (SLS) is determined based on analysis solving the problem of stability of liquid column in the gravity and capillary forces field. On the grounds of obtained relationships the optimization of pulse-periodical laser radiation power and SLS-process duration is realized, that allows to produce voluminous powder porous materials with pre-determined physical and mechanical properties and surface geometry. Results of metallographic investigations of powder porous materials of titanium powder produced with technological regimes calculated by means of obtained relationships are given in the work

• Journal of Korea Technology Innovation Society
• /
• v.15 no.4
• /
• pp.815-836
• /
• 2012

Corporate Laboratories have been a key driver of Korea's economic growth through attaining technology competitiveness. The study is focused on selecting outstanding small and medium corporate laboratories with high R&D capability and fostering the selected laboratories. The main topics of this study are to establish logics regarding the selection process and to propose the implementation schemes of the process. For the selection of outstanding laboratories, this study presents a evaluation indicators based on logic model and verification of the validity of following evaluation indicators through a Pilot test. The evaluation indicators from this study are expected to be in practical use as a reference for support policies of outstanding laboratories' R&D activities. For corporations, these indicators can be used to examine their R&D capability. This study also suggests differentiated policy support measures using the findings to maximize the effectiveness of the selection process.

• Journal of electromagnetic engineering and science
• /
• v.7 no.4
• /
• pp.169-174
• /
• 2007

This paper presents a method of superimposing the rotation phases over the pilot and data symbols in order to reduce the peak-to-average power ratio(PAPR) in orthogonal frequency division multiplexing(OFDM). The phases of the rotation vector are added to those of the pilot symbols and those of the data symbols by interlaying them between any two pilot symbols. The receiver restores the data symbols by utilizing the channel estimation of the pilot symbols. Therefore, the bandwidth efficiency is improved by not using the subcarriers that are assigned for the reduction of the PAPR. Also, the enormous increase of the bit error rate which would be caused by incorrectly receiving the side information, i.e. the phases of the rotation vector, is prevented. The simulation results of the bit error rate performance for the BPSK are given using the COST-207 channel model.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.599-602
• /
• 2002

A novel rapid prototyping (RP) process, an automated transfer type variable lamination manufacturing process (Automated VLM-ST) has been developed. In Automated VLM-ST, a vacuum chuck and linear moving system transfer the plate type material with two pilot holes to the rotation stage. A four-axis synchronized hotwire cutter cuts the material twice to generate Automated Unit Shape Layer (AUSL) with the desired width, side slopes, length, and two reference shapes in accordance with CAD data. Each AUSL is stacked on the stacking plate with two pilot pins using the pilot holes in AUSL and the pilot pins. Subsequently, adhesive is supplied to the top surface of the stacked AUSL by a bonding roller and pressure is simultaneously applied to the bottom surface of the stacked AUSL. Finally, three-dimensional shapes are rapidly fabricated. This paper describes the procedure for generating the cutting path data (AUSL data) f3r automated VLM-ST. The method for the generation of the Automated Unit Shape Layer (AUSL) in Automated VLM-ST was practically applied and fabricated for a various shapes.

• Journal of the Korean Institute of Gas
• /
• v.21 no.3
• /
• pp.26-32
• /
• 2017

Outer tank concretes of LNG storage tank are composed of prestressed concrete structures that act as a protective wall. The danger such as the collapse of structures will exist if concrete structures is not secured due to the deterioration. Concrete compressive strength directly related to the safety of structures can be predicted by using estimation equation of compressive strength through rebound hardness test and ultrasonic wave velocity method. But, there is no the estimation equation of LNG storage tank for a relation between NDT data and real strength. In this study, to obtain more accurate real strengths for LNG storage tank, core specimens were sampled from walls of pilot LNG storage tank. The rebound hardness test of general NDT for concrete structures was carried out at each 3 positions for the four areas. The compressive strength estimation equation of LNG storage tank was developed by using the data for rebound hardness test of pilot LNG storage tank and compressive strength test of sampled concrete cores.

• Clean Technology
• /
• v.12 no.2
• /
• pp.67-77
• /
• 2006

A simple dual sludge process, called as $KNR^{(R)}$ (Kwon's Nutrient Removal) system, was developed for small sewage treatment. It is a hybrid system that consists of an UMBR (Upflow multi-layer bioreactor) as anaerobic and anoxic reactor with suspended denitrifier and a post aerobic biofilm reactor, filled with pellet-like media, with attached nitrifier. To evaluate the stability and performance of this system for small sewage treatment, the pilot-scale $KNR^{(R)}$ plant with a treatment capacity of $50m^3/d$ was practically applied to the actual sewage treatment plant, which was under retrofit construction during pilot plant operation, with a capacity of $50m^3/d$ in a small rural community. The HRTs of a UMBR and a post aerobic biofilm reactor were about 4.7 h and 7.2 h, respectively. The temperature in the reactor varied from $18.1^{\circ}C$ to $28.1^{\circ}C$. The pilot plant showed stable performance even though the pilot plant had been the severe fluctuation of influent flow rate and BOD/N ratio. During a whole period of this study, average concentrations of $COD_{cr}$, $COD_{Mn}$, $BOD_5$, TN, and TP in the final effluent obtained from this system were 11.0 mg/L, 8.8 mg/L, 4.2 mg/L, 3.5 mg/L, 9.8 mg/L, and 0.87/0.17 mg/L (with/without poly aluminium chloride(PAC)), which corresponded to a removal efficiency of 95.3%, 87.6%, 96.3%, 96.5%, 68.2%, and 55.4/90.3%, respectively. Excess sludge production rates were $0.026kg-DS/m^3$-sewage and 0.220 kg-DS/kg-BOD lower 1.9 to 3.8 times than those in activated sludge based system such as $A_2O$ and Bardenpho.

• Journal of Energy Engineering
• /
• v.29 no.1
• /
• pp.58-62
• /
• 2020

Among the exhaust gas, Carbon dioxide which is a causative factor in greenhouse effect. We study for synthesis of propylene carbonate with carbon dioxide which is captured and utilized in commercially valuable. The Experiment was proceeded as pilot scale with using homogeneous organic catalyst which is able to produce propylene carbonate in commercial and reaction conditions. Optimization condition for concentration of catalyst and reaction temperature, pressure was studied. We confirm that this process is eco-friendly method and commercial application due to the mild condition and also catalyst has a competitive price, reusability.

• Membrane Journal
• /
• v.4 no.4
• /
• pp.213-220
• /
• 1994

Reverse osmosis(R/O) pilot system, which consists of pretreatments and R/O membranes, was demonstrated to regenerate the petroleum refinery wastewater for the process feedwater supply. Despite of the unsteady quality of the wastewater effluent from the process facilities, relatively high salt rejection of 96~99% was obtained and the product water showed a feasible quality for the use of cooling tower feed water. The results of R/O membrane module cleaning with NaOH solution represented that there was some fouling effects on the membrane performance during the period of test due to the ineffective treatment processes proposed and used in this study.

• Journal of Radiation Protection and Research
• /
• v.38 no.1
• /
• pp.44-51
• /
• 2013

ICRP recommended that cosmic ray exposure to the pilot and cabin crew would be considered as an occupational exposure due to their relatively high exposure. Since 2012 with the Act No. 10908 (Natural radiation management), the guideline of cosmic ray exposure to the pilot was established in Korea. The applicability of the solid-state nuclear track detector for personal dose assessment of pilot and cabin crew was evaluated. Dose linearity and angle dependence of dosimeters to the neutron were evaluated by $^{252}Cf$ neutron emitting source. The track density has a good agreement with the dose ($r^2$=0.99) and highly dependent on the degree of an angular of the dosimeter to the neutron source. In addition, the dosimeters (SSNTD) were exposed to cosmic ray in an aircraft during its cruising for more than two months in collaboration with Airline Pilots Association of Korea. Although the correlation between the track density from aircraft cruising altitude and expected neutron dose is low, however RSNS dosimeter could be used for personal neutron dosimeter. For application of RSNS as a personal dosimeter for pilot and cabin crew, additional studies are required.

• The korean journal of orthodontics
• /
• v.46 no.3
• /
• pp.180-185
• /
• 2016

The incorporation of technological advances in the field of clinical orthodontics to increase treatment efficiency has led to the development of customized appliances (Insignia$^{(R)}$), archwires (Suresmile$^{(R)}$), and the production of devices to enhance tooth movement (Acceledent$^{(R)}$). This review presents a comprehensive study of the literature concerning these products, and analyzes the available evidence of their efficiency. To date, one pilot study has evaluated the efficiency of the Insignia$^{(R)}$ system, three retrospective studies have assessed the efficiency of the Suresmile$^{(R)}$ system, and a few Acceledent$^{(R)}$ reports have described its effect on treatment time. Critical appraisal of the reviewed papers revealed that the efficiency of the Insignia$^{(R)}$ system cannot be confirmed based on the available evidence, while the use of Suresmile$^{(R)}$ can reduce overall treatment time in simple cases. The acceleration of tooth movement by Acceledent$^{(R)}$ devices has not yet been confirmed.