• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.2
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• pp.31-41
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• 1986

Knowledge of the degree of yield reduction due to water stress at different crop growth stages in rice production is important for rational scheduling of irrigation during periods of insufficient water supply. Previous studies to determine the degree of yield reduction duo to water stress suffered from interruptions by rain during experiment. Also the findings did rot relate the degree of water stress to the soil water potential and water deficit status of rice plants. In this study, two years experiments were conducted using the high yielding rice varieties, an Indica x Japonica (Nampoong) and a Japonica variety(Choochung). These were grown in 1/200$^{\circ}$ plastic pots placed under a rainfall autosensing, sliding clear plastic roof facility to control rainfall interruptions. The results obtained were as follows. 1.The two varieties differed in the growth stage most sensitive to water stress as well as the degree of yield reductions. When rice plants were stressed to the leaf rolling score 4 and soil water potential of about - 20 bar at major crop growth stages which included heading, booting, non-effective tillering, panicle initiation and early tillering stages, the yield reductions in the Indica x Japonica variety were 58%, 34%, 27%, 22%, and 21%, respectively, whereas in the Japonica vairety they were 23%, 36%, 1%, 13% and 22%, respectively. This result show that the recommended drainage during non-effective tillering is valid only for the Japonica variety. Sufficient irrigation at booting, heading and early tillering stages are necessary for both varieties. 2.The two varieties showed visible wilting symptoms when the soil water potential dropped to about - 3.0 bar. The Japonica variety showed more leaf rolling than the Indica X Japonica. However, it had a higher retention of leaf water content and greater stomatal diffusive resistance. When the soil water potential dropped, the Japonica variety showed leaf rolling score (LRS) 1 at 0 soil-5. 0 bar and LRS 2 at 0 soil -6.0 bar while the Indica X Japonica showed LRS 1 at 0 soil - 5.5 bar and LRS 2at 0 Soil - 9.0 bar. The stomatal diffusive resistance was maximum at the second top leaf blade in both varieties at intermediate water stress of 0 soil - 4.5 bar. 3.The number of days that was required for the soil water potential to drop to-3. 0 bar and to - 20.0 bar after drainage of irrigation water from the 20cm deep silty clay loam soil in the pots were 6 and 13 days, respectively for booting stage, and 7 and 11 days, respectively for heading stage, 9 and 12 days, respectively for panicle initiation stage, and 12 and 19 days, respectively for early tillering stage. 4.Water stress during the early tillering stage recorded the longest delay in beading time, the largest reduction in panicle numbers and a substantial yield decrease of 20%. This calls for better water management to ensure the availability of water at this stage, particularly during drought periods. In addition, a reexamination of the conventional inter-drainage practice during the non-effective tillering stage is necessary for the high yielding Indica X Japonica varieties.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1996.05a
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• pp.91-115
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• 1996

In the recent years, protected horticultural facilities have been modernized and glasshouses are also propagating in Korea, even most vegetables production are conducted in the traditional plastic houses covered with, for example, PVC film for just temperature keeping. It would limit the productivity and competitivity of the vegetable production industry without automatization and high quality year round production. A plant factory, aimed to produce vegetables in the limited areas, was initiated in Christensen farm, Denmark in 1957, and widely propagated in some developed countries. As it has the automatized system which enables to keep optimized environment conditions, it will be the best facility for high quality products as well as year round planned production. However, we have not even started the plant factory production. Since the plant factory is requiring lots of resources, besides plant cultivation technologies, such as environment control, automatic engineering and robotics, our approach to the development of plant factories should be minded on Practical Plant Factories considering our current farming practices and least capital needs rather than blindly employing the advanced technologies from developed countries. Thus, Korean plant factory development can be initiated with year round leaf vegetables production in NFT or DFT cultivation system instead of the moval bed system, in which aerial environment factors such as light, temperature, humidity and CO$_2$ concentration and root environment ones such as solution concentration, temperature, pH and water soluble oxygen shall be automatically controlled. And the seeding, seedling and transplanting operations shall be accomplished in the house entrance, and the harvesting and grading opreations shall be conducted in the house exit. For practical plant factories, environment control technologies including artificial light source, illumination and air conditioning, automatic management for nutrient solution and automatic production line of moval bed system, transplanting and harvest should be developed along with researches on the cost reduction of factory building construction.

• The Journal of the Korea Contents Association
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• v.18 no.8
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• pp.469-482
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• 2018

This research has developed the criteria and index for systematically and objectively assessing the quality of river water by fixing the various factors that affect Gyeongin ARA waterway's water quality through analysis with the Delphi Technique and analytic hierarchy program (AHP) Method. Based on the results, the highest criteria are, in order of importance, physical and environmental factors 28%, administrative factors 26%, natural fixed factors 26% and finally, cultural and social factors 20%. The three dimensions of the criteria show that for the internal physical and environmental factors, the most important are the loss of self-purification capacity, and the external factors are Gulpocheon and the sludge deposit due to Gyulhweon-weir the bridge. The facility factor in management was affected by the coagulation and waste water disposal facilities. The problem for the policy and institutional factors was seen in the regulatory area. The aquatic ecology/ point pollution source for the natural fixed factors show that it is due to the polluted water of Gulpo-cheon and the living environment/ non-point pollution source is shown through the inflow water from other rivers. Cultural and social factors show that the economical causes were due to the cargo and passenger flight operations and the external factors of having a lack of sewage treatment equipment have an importance effect. In order to estimate the order of priority through logical evidence and objectivity, future research must be continued on the evaluation indexes to measure the specific methodology and technique needed to improve the Gyeongin ARA Waterway.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.142-148
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• 2017

Along with economic growth in the 1970s, the nation's economy, railroads, and airports have soared, but the facilities have been aging for 30 years. The aging SOC lowers the national competitiveness and threatens the safety of the people. SOC is a key asset of the national life and economic activity, and is a key factor for evaluating the national competitiveness. Therefore, it is necessary to systematically manage and operate the SOC related to people's lives. In the USA, the SOC report card is issued regularly. Those reports are used as a basis for securing budgets. In Korea, facilities management institutions are different. Therefore, there is no integrated SOC monitoring system. Hence, this study developed a 'SOC information system' that can collect reports scattered throughout the country and support report cards. The demonstration system was implemented through the web and the feasibility of implementing the evaluation support system was confirmed. The collection distributed SOC data should be supported by national policy. Although it takes a long time, it is necessary to improve national competitiveness and public safety.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.258-266
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• 2011

Scale induced by hardness materials in water must be controled because of it can be result in remarkable damages of pipeline as well as water quality deterioration. Especially hot water system is one of scale management required facility as scale formation can be accelerated by temperature. The scale control performance of frequency driver (FD) was tested instead of existing methods such as chemical, physical and electromagnetic methods which needs chemicals and electric power. Three kinds of pipe coupons were submerged in test water with 500 mg/L of hardness for 33 days and XRD and SEM were analysed for comparing scale formation characteristics of these coupons. Calcite ($CaCO_3$) which came from hardness of water was formed on only cast iron pipe coupon and this coupon showed higher corrosion rate than copper and stainless steel pipe coupon. Hot water circulating system connected cast iron pipe with and without FD was operated with 300 mg/L of hardness water at $50^{\circ}C$ for monitoring of scale formation and water quality with and without FD. XRD showed that FD leaded to magnetite ($Fe_3O_4$) scale which is good scale for preventing corrosion than calcite and SEM image also indicated the scale control effect of FD. Scales of 16% on pipe joint, 14% on pipe length, and 42% on heat exchanger decreased with FD comparing scales of those parts without FD. From the results of water quality, FD reduced crystallization of hardness material without chemical reaction in water and it can indicate that FD is safe and proenvironmental technology for scale reduction.

• Journal of Distribution Science
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• v.10 no.10
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• pp.25-33
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• 2012

Purpose - The Garak agricultural wholesale market ('Garak Market') plays a central role in the distribution of agricultural products in Korea and is important in connecting consumers with producers. However, problems regarding inefficiencies and the high-cost structure of the wholesale market's distribution/logistical system are being raised in relation to severe competition among retailers. Furthermore, the service needs of retailers and market users are not being fulfilled due to the inconsistency of the wholesale market's functions and facilities, thus reducing the competitiveness of the market. In this regard, innovative changes are being requested of the agricultural wholesale market according to changes in the agricultural product distribution environment. In particular, the lack of unloading facilities and the outdated unloading system of the wholesale market must be improved to enhance system efficiency. Research design, data, and methodology - This study observed the problems of the unloading system of the agricultural wholesale market in order to present relevant measures for improvement. The need for unloading auctions was also researched in this study. The survey of 70 forwarders belonging to the producing district distributor association of the Garak market was conducted by post. Additionally, 20 auction dealers and 59 shippers and transporters were individually interviewed. The survey on the need for unloading auctions used five-point Likert Scales. The statistical analysis was conducted with SPSS WIN 12.0 software. Results - First, the wholesale market must employ members of the unloading labor union to allow these employees to directly manage the unloading process. Second, it is crucial to revise regulations to ensure that the principal agent pays the unloading cost according to the standard unloading cost system. Third, the vehicle auction carried out for certain vegetable products must be converted to the unloaded auction system. According to the related interviews with the wholesale market's distribution agents, whereas shippers and transporters recognized the need for unloaded auctions, auction dealers tend to have a negative view of this system. Furthermore, the stated reasons in favor of unloaded cabbage, radish, and other vegetable auctions were prevention of constraint, creation of transparent trade conditions, and reduction of corrected seller tickets. Many of the respondents answered that the transport cost reduction rate in unloaded auctions must be below 20%. Fourth, the unloading system must be mechanized and a detailed, reasonable plan must be provided to settle the existing conflict with the unloading labor union. Conclusions - The proposals in this study are expected to play an important role in improving the cargo handling system of the wholesale agricultural product market in the future. Improving the system is expected to help shore up the competitiveness of the industry. If all the related bodies closely cooperate with each other and work harder, taking advantage of the synergies created by the facility modernization project, the Garak market will play a pivotal role in the distribution of agricultural products.

• Journal of Navigation and Port Research
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• v.41 no.3
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• pp.137-148
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• 2017

Port service level is a metric of competitiveness among ports for the operating/managing bodies such as the terminal operation company (TOC), Port Authority, or the government, and is used as an important indicator for shipping companies and freight haulers when selecting a port. Considering the importance of metrics, we developed software to objectively define and manage six important service indicators exclusive to container and bulk terminals including: berth occupancy rate, ship's waiting ratio, berth throughput, number of berths, average number of vessels waiting, and average waiting time. We computed the six service indicators utilizing berth 1 through berth 5 in the container terminals and berth 1 through berth 4 in the bulk terminals. The software model allows easy computation of expected ship's waiting ratio over berth occupancy rate, berth throughput, counts of berth, average number of vessels waiting and average waiting time. Further, the software allows prediction of yearly throughput by utilizing a ship's waiting ratio and other productivity indicators and making calculations based on arrival patterns of ship traffic. As a result, a TOC is able to make strategic decisions on the trade-offs in the optimal operating level of the facility with better predictors of the service factors (ship's waiting ratio) and productivity factors (yearly throughput). Successful implementation of the software would attract more shipping companies and shippers and maximize TOC profits.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.119-127
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• 2011

The main purpose of this paper is to apply Zone 30 system which is being experimented in advanced country for the solution of controlling the residential street's speed to our country with the consideration of the real condition of our street and traffic and to run this system as an example to analyze the effect and at the same time, analyze the problem and get appropriate preparation for this system to be widespread. The area to run this model project is Goyang City Ilsan-Gu.($0.65km^2$) which is close with the commercial area reflecting the opinion of experts and an on-site verification by the National Police Agency T/F and is having a heavy pedestrian traffic and the risk of pedestrian accident. Firstly we defined residential street and residential street area to review the system and devided the residential street type to establish a plan of operation. Afterwards, we thoroughly examined the model project area and analyzed the problem and solution. We finally completed establishing a facilities by conference with a local autonomous entity with the improvement of facility's sketch at the analysis of the model project area. The result of effects analysis which we devided after and before of establishment is that vehicle speed be reduced 5~15km/h, and traffic accidents has decreased by 24 percent.

• Nuclear Engineering and Technology
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• v.46 no.3
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• pp.439-446
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• 2014

An amphibious inspection robot system (hereafter AIROS) is being developed to visually inspect the in-containment refueling storage water tank (hereafter IRWST) strainer in APR1400 instead of a human diver. Four IRWST strainers are located in the IRWST, which is filled with boric acid water. Each strainer has 108 sub-assembly strainer fin modules that should be inspected with the VT-3 method according to Reg. guide 1.82 and the operation manual. AIROS has 6 thrusters for submarine voyage and 4 legs for walking on the top of the strainer. An inverse kinematic algorithm was implemented in the robot controller for exact walking on the top of the IRWST strainer. The IRWST strainer has several top cross braces that are extruded on the top of the strainer, which can be obstacles of walking on the strainer, to maintain the frame of the strainer. Therefore, a robot leg should arrive at the position beside the top cross brace. For this reason, we used an image processing technique to find the top cross brace in the sole camera image. The sole camera image is processed to find the existence of the top cross brace using the cross edge detection algorithm in real time. A 5-DOF robot arm that has multiple camera modules for simultaneous inspection of both sides can penetrate narrow gaps. For intuitive presentation of inspection results and for management of inspection data, inspection images are stored in the control PC with camera angles and positions to synthesize and merge the images. The synthesized images are then mapped in a 3D CAD model of the IRWST strainer with the location information. An IRWST strainer mock-up was fabricated to teach the robot arm scanning and gaiting. It is important to arrive at the designated position for inserting the robot arm into all of the gaps. Exact position control without anchor under the water is not easy. Therefore, we designed the multi leg robot for the role of anchoring and positioning. Quadruped robot design of installing sole cameras was a new approach for the exact and stable position control on the IRWST strainer, unlike a traditional robot for underwater facility inspection. The developed robot will be practically used to enhance the efficiency and reliability of the inspection of nuclear power plant components.

• Korean Journal of Childcare and Education
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• v.7 no.1
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• pp.41-65
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• 2011

The purpose of this study was to examine the influence of satisfaction with workplace child-care on the parenting stress, job commitment, and job satisfaction of parents. The questionnaires survey of this study was conducted on 185 parent-employees (97 fathers & 88 mothers) who used employer-supported child-care in the province of Kyungki-do. The results of this study were as follows: As the level of satisfaction with workplace child-care became higher, the level of parenting stress became lower. And as the level of satisfaction with workplace child-care became higher, the level of job commitment and job satisfaction became higher. Among five components of satisfaction with workplace child-care, satisfaction with the environment for child-care had an independent influence on parenting stress. And satisfaction with the management of child-care facility had an independent influence on job commitment and job satisfaction. This study suggested that education programs that target employers need to raise employers' awareness about the importance of workplace child-care in order to reduce parenting stress and to enhance job commitment and job satisfaction of parent-employees.