• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.8 no.2
• /
• pp.116-116
• /
• 1999

In this study we propose a novel approach with which design engineers can define and design free-from surface more easily. Free-from surface is defined as a parameterics shape which consists of a set of contr ol points. Parametric shape which not only has the advantage of allowing users to perform design changes efficiently, but also provides designers with a natural design environment in which they can do their work more naturally and creatively. The objective of this study is to develop a PC level freeform surface modelling system which explicitly represents information of part geometry. In this study, freeform surface modeling system consist of three modules : freeform surface modeler, input/output modules and interface with Database. In recent year there are increasing demands for the 5-axis machining of a complicated shape. This study is the development of a CAM software system (or NC module) for the 5-axis machining of a general shape with a flat-end mill, a round-end mill, a ball-end mill.

• Journal of Korean Society of Water and Wastewater
• /
• v.34 no.2
• /
• pp.93-104
• /
• 2020

As water resources are limited and legal regulations are strengthened, there is a growing need to reuse residuals in WTP(Water Treatment Plant). In this study, membrane filtration system was constructed and its operation method was studied for water quality stabilization and reuse of WTP residuals. The operation parameters were stable for 1 year and 6 months. Membrane fouling was identified as particulate pollution (activated carbon) and inorganic pollution (manganese). The membrane system was operated steadily with raw water of high concentration SS(Suspended solid) containing activated carbon because membrane fouling was reduced by the effect of End-Free type. In the case of inorganic contamination, dissolved manganese eluted by chemicals and acted as a membrane fouling source, and the operating conditions for minimizing membrane fouling. were confirmed by newly developing application methods and types of cleaning chemicals. Based on the results, design parameters for reducing manganese membrane fouling were derived.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.16 no.1
• /
• pp.9-16
• /
• 1996

'This experiment was canied out to investigate the effects of endophyte status(end0phyte-free and -infect) and cutting frequency(3, 4, 5 and 6 timeslyear) on the agronomic characteristics, DM yield and weed development of tall fescue(Festuca arundinacea Schreb.) at the Experimental Field of Grassland and Forage Crops Division, National Livestock Research Institute, Suweon, from 1993 to 1994. 'Ihe results obtained are summarized as follows: DM yield of endophyte-infected tall fescue was slightly higher than that of endophyte-free tall fescue. DM yield of two tall fescue varieties was significantly decreased with frequent culting(p<0.05). Weed development of pasture tended to be decreased with endophyte-infected tall fescue and infrequent cutting, and endophyte-infected tall fescue had a good adaptation to the poor environment. Based on the results of this experiment, it is suggested that a slight increase in forage yield could be obtained from endophyte-infected tall fescue and endophyte-infected tall fescue was more persistant than endophyte-free tall fescue under poor conditions.

• Asian-Australasian Journal of Animal Sciences
• /
• v.6 no.4
• /
• pp.619-622
• /
• 1993

Rumen bacterial amino acids in sheep on urea diet were monitored to assess a possible change in amino acid synthesis as a long term response to high rumen ammonia environment. A sheep was fed a semipurified diet with soybean meal, followed by a diet with urea as a main nitrogen source. Mixed rumen bacteria were harvested from ruminal fluid taken 3 h after feeding (twice in soybean meal feeding and 6 times in urea feeding) and fractionated as cell wall, proteins and protein-free cell supernatant of monitor amino acids in each fraction. Ruminal ammonia concentration at the sampling ranged from 5.7 to 39.5 mgN/dl. Cell wall and protein fractions of mixed rumen bacteria were stable in their amino acid composition regardless of nitrogen sources of diet and the feeding duration. However, protein-free cell supernatant fraction showed a higher alanine proportion with urea feeding (18.6 and 28.2 molar % of alanine for samples from sheep fed soybean meal and urea, respectively) and its duration (20.6 and 32.9 molar % for samples from sheep on urea diet for 1 and 65 days, respectively). Total free amino acid level of bacteria was depressed in the initial period of urea feeding but restored on 65th day of the feeding. These results suggest that an alanine synthesizing system may develop in rumen bacteria as urea feeding becomes longer.

• Journal of Applied Reliability
• /
• v.5 no.2
• /
• pp.241-259
• /
• 2005

The environmental problem is a main subject of the 21C and an environment destruction phenomenon by various kinds of environmental materials is reaching serious level. Nations to be classified as the environmental developed country, are born again environmental rich country. And they earn a large income by trade Every kind environmental resource in an international commercial transaction. Especially, the study that a reliability assessment method to prevent to reliability problem to be happened when the solder lead(lead-free solder), non-cd component, non-bromide component(without the polybrominated biphenyls(PBB) and polybrominated diphenyl ethers(PBDE))and hexavalent chromium(Cr VI) clearance component and mercury-free applied to electronic equipment is progressed. As the result of the study for applying of a reliability assessment technique of lead-free solder that recognized the most of urgent problem at the company, combination accelerated life test could taken by adding and appling the part of a humidity acceleration part to Eyring Model which is proposed by R.E.Thomas. The reliability assessment methods study of PWB clean environmental materials is expected to respond to a reliability elevation and environmental material regulation policy spreading all over the world by beginning form Europe.

• Korean Journal of Agricultural Science
• /
• v.37 no.1
• /
• pp.37-43
• /
• 2010

This study carried out to develop barrier-free certification program in forest trail. It is done to provide the certification system presented about certification organized, certification standard and indexes, evaluation method and operation plan. In order to develop certification program in forest trail, detailed measurement index must be developed earlier based on an accessbility, a stability, a preservation and a walking continuity. The suitable forest trail for weak pedestrian was investigated that running slope should be 1/20(5%) maximum, cross slope cannot exceed 1/50(2%) maximum and clear tread width should be above of minimum 90cm. In addition, the trail type is designed as a mixed trail system which is a combination of the loop and the line form and its distance should be 225~675m. Finally, forest trail should be manage sustainably by having regular monitoring and evaluation.

• ETRI Journal
• /
• v.38 no.3
• /
• pp.579-588
• /
• 2016

To improve the ability to determine a vehicle's movement information even in a challenging environment, a hybrid approach called non-Gaussian square rootunscented particle filtering (nGSR-UPF) is presented. This approach combines a square root-unscented Kalman filter (SR-UKF) and a particle filter (PF) to determinate the vehicle state where measurement noises are taken as a finite Gaussian kernel mixture and are approximated using a sparse Gaussian kernel density estimation method. During an outage-free GPS period, the updated mean and covariance, computed using SR-UKF, are estimated based on a GPS observation update. During a complete GPS outage, nGSR-UPF operates in prediction mode. Indeed, because the inertial sensors used suffer from a large drift in this case, SR-UKF-based importance density is then responsible for shifting the weighted particles toward the high-likelihood regions to improve the accuracy of the vehicle state. The proposed method is compared with some existing estimation methods and the experiment results prove that nGSR-UPF is the most accurate during both outage-free and complete-outage GPS periods.

• Journal of Welding and Joining
• /
• v.32 no.3
• /
• pp.74-80
• /
• 2014

Due to environmental regulations (RoHS, WEEE and ELV) of the European Union, electronics and automotive electronics have to eliminate toxic substance from their devices and system. Especially, reliability issue of lead-free solder joint is increasing in car electronics due to ELV (End-of-Life Vehicle) banning from 2016. We have prepared engine control unit (ECU) modules soldered with Sn-40Pb and Sn-3.0Ag-0.5Cu (SAC305) solders, respectively. Degradation characteristics of solder joint strength were compared with various conditions of automobile environment such as cabin and engine room. Thermal cycle test (TC, $-40^{\circ}C$ ~ ($85^{\circ}C$ and $125^{\circ}C$), 1500 cycles) were conducted with automotive company standard. To compare shear strength degradation rate with eutectic and Pb-free solder alloy, we measured shear strength of chip components and its size from cabin and engine ECU modules. Based on the TC test results, finally, we have known the difference of degradation level with solder alloys and use environmental conditions. Solder joints degradation rate of engine room ECU is superior to cabin ECU due to large CTE (coefficient of thermal expansion) mismatch in field condition. Degradation rate of engine room ECU is 50~60% larger than cabin room electronics.

• Fashion & Textile Research Journal
• /
• v.18 no.2
• /
• pp.139-148
• /
• 2016

There is an expanding global network of free trade agreements (FTA). High-quality, comprehensive free trade agreements play an important role to support global trade liberalization and are explicitly allowed under the World Trade Organization (WTO) rules. An FTA is an international treaty that removes barriers to trade and facilitates stronger trade and commercial ties that contribute to increased economic integration between participating countries. Korea benefits from the global FTA trend; however it has started and developed FTA negotiations later than other countries. Current FTA agreements exist with Chile, Singapore, EFTA, ASIAN, India, EU, Peru, USA, Turkey, Australia, and Canada; in addition, there are ongoing negotiations with China, Colombia, New Zealand, and Vietnam. FTA open up opportunities for the textile/clothing industry to expand businesses into key overseas markets. FTA improve market access across all areas of trade to help maintain and stimulate the competitiveness of textile/clothing firms. This study examines the expansion of free trade agreements in light of changes in the international trade environment and the status of the Korean textile/clothing industry. Korea's textile/clothing export/import products and concession of tariff, country of origin covered under Korea-US/China FTA are investigated to identify problems. This study provides practical and policy implications for the textile/clothing industry in regards to the Korea-US/China FTA.

• Journal of Korean Society of Water and Wastewater
• /
• v.33 no.5
• /
• pp.379-388
• /
• 2019

Chlorination and UV illumination are being widely applied to inactivate a number of pathogenic microbials in the environment. Here, we evaluated the inactivation efficiency of individual and combined treatments of chlorination and UV under various aqueous conditions. UV dosage was required higher in waste water than in phosphate buffer to achieve the similar disinfecting efficiency. Free chlorine generated by electrolysis of waste water was abundant enough to inactivate microbials. Based on these, hybrid system composed of sequential treatment of electrolysis-mediated chlorination and UV treatment was developed under waste water conditions. Compared to individual treatments, hybrid system inactivated bacteria (i.e., E. coli and S. typhimurium) and viruses (i.e., MS-2 bacteriophage, rotavirus, and norovirus) more efficiently. The hybrid system also mitigated the photo re-pair of UV-driven DNA damages of target bacteria. The combined results suggested the hybrid system would achieve high inactivation efficiency and safety on various pathogenic microbials in wastewater.