• Journal of the Korean Society of Clothing and Textiles
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• v.48 no.2
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• pp.312-327
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• 2024

In this study, a rehabilitation 3D printed wearable device was developed by combining an assembly-type robot hand and an integral-type robot hand through fused deposition 3D printing manufacturing with various hardness TPU (Thermoplastic Polyurethane) filaments. The hardware configuration of the robot hand includes a controller designed with four motors, one small servo motor, and a circuit board. In the case of the assembly-type robot hand model, a 3D printed robot hand was assembled using samples printed with TPU of hardness 87A and 95A. It was observed that TPU with a hardness of 95A was suitable for use due to shape stability. For the integrated-type robot hand model, the external sample using TPU of hardness 95A could be modified through a cutting method, and the hardware configuration is the same as the assembly-type. The system structure of the 3D printed robot hand was improved from an individual control method to a simultaneous transmission method.Furthermore, the system architecture of an integrated 3D printed robotic hand rehabilitation device and the application of the rehabilitation device were developed.

• Information Systems Review
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• v.22 no.4
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• pp.59-74
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• 2020

This paper investigates the asymmetric effect of social sentimental on an individual stock price return. For this purpose, four companies such as POSCO, Korean Electricity, AMORE PACIFIC, KIA Motors are chosen from KOSPI listed companies in terms of dataperspective. The main estimation results are as follows: the positive opinions affect only the stock prices return of three companies while the negative opinions affect all of the companies. It shows that positive or negative texts give asymmetric effect on stock price return and the effect of negative opinions is bigger than that of positive opinions. The results imply that investors are more sensitive to the negatives since they have the tendency of loss aversion. Also, it indicates that subjective opinion on SNS can be used as the proxy for the investment sentiment.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.386-392
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• 2024

This paper constructs a precise dynamics model using flightlab, a specialized program for rotor modeling and performance analysis, to simulate urban air mobility (UAM). flightlab is well-suited for detailed modeling of UAM, particularly requiring detailed aerodynamic characteristics under high-altitude and urban wind conditions. The study focuses on implementing and analyzing a lift-cruise UAM model with distributed propulsion using flightlab. The lift-cruise model integrates motors for vertical take-off and fixed-wing flight. Given the limited specific examples of such UAM models in flightlab and challenges in evaluating with conventional fixed-wing or drone models, this research implements and verifies the lift-cruise model using matlab, comparing its performance against flightlab results to validate the modeling approach. This research aims to explore the potential of flightlab for detailed UAM modeling and contribute to technological advancements in future urban transportation.

• Archives of Metallurgy and Materials
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• v.63 no.3
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• pp.1433-1437
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• 2018

Neodymium-Iron-Boron (Nd-Fe-B) magnets are considered to have the highest energy density, and their applications include electric motors, generators, hard disc drives, and MRI. It is well known that a fiber structure with a high aspect ratio and the large specific surface area has the potential to overcome the limitations, such as inhomogeneous structures and the difficulty in alignment of easy axis, associated with such magnets obtained by conventional methods. In this work, a suitable heat-treatment procedure based on single-step and multistep treatments to synthesize sound electrospun Nd-Fe-B-O nanofibers of Φ572 nm was investigated. The single-step heat-treated (directly heat-treated at 800℃ for 2 h in air) samples disintegrated along with the residual organic compounds, whereas the multistep heat-treated (sequential three-step heat-treated including three steps;: dehydration (250℃ for 30 min in an inert atmosphere), debinding (650℃ for 30 min in air), and calcination (800℃ for 1 h in air)) fibers maintained sound fibrous morphology without any organic impurities. They could maintain such fibrous morphologies during the dehydration and debinding steps because of the relatively low internal pressures of water vapor and polymer, respectively. In addition, the NdFeO3 alloying phase was dominant in the multistep heat-treated fibers due to the removal of barriers to mass transfer in the interparticles.

• Journal of Drive and Control
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• v.21 no.3
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• pp.56-69
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• 2024

Tractors are used for farming in harsh terrain such as slopes with slippery fields and steep passages. In these potentially dangerous terrain, steering instability caused by bouncing and sliding can lead to tractor rollover accidents. The center of gravity changes as parts such as engines and transmissions used in existing internal combustion engine tractors are replaced by motors and batteries, and the risk of conduction must be newly considered accordingly. The purpose of this study was to derive the center of gravity of a 55 kW class electric tractor using an electric platform from an existing internal combustion engine tractor, and to numerically investigate the tractor steering instability due to bouncing and sliding. The analysis provides a strong analysis by integrating an elaborate combination of a bouncing model and a sliding model based on Coulomb's theory of friction. Various parameters such as tractor speed, static coefficient of friction, bump length and radius of rotation are carefully analyzed through a series of detailed designs. In particular, the simulation results show that the cornering force is significantly reduced, resulting in unintended trajectory deviations. By considering such complexity, this study aims to secure optimal performance and safety in the challenging terrain within the agricultural landscape by providing valuable insights to improve tractor safety measures.

• The Journal of the Convergence on Culture Technology
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• v.10 no.5
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• pp.687-692
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• 2024

Recently, electric skateboards have been used as a means of personal transportation due to their convenience and simplicity of operation, but the conventional skateboards driven by timing belts or hub motors have disadvantages such as low driving torque, high current and vibration. Therefore, in this paper, we propose a new type of electric skateboard that can run at high speeds for long periods of time so that it can be used as a auxiliary means of transportation. The planetary gear and motor unit are combined and installed inside one drive wheel, and power is supplied to the wheel through the integrated driving unit to prevent high currents and enable high-speed driving. First, the allowable current and running speed of the electric skateboard were set for efficient personal transportation and the appropriate reduction ratio, modules, and planetary gear dimensions were determined by comparing the torque required for the wheel axis and the maximum output torque of the motor. Additionally, an appropriate suspension device was added to reduce driving vibration for user convenience, and the feasibility of the proposed in-wheel gearbox was experimentally verified through fabrication.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.4
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• pp.3943-3955
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• 1975

The purposes of this study are to evaluate the utilization characteristics of electrical power consumption, to grasp the present trends in the use of electrical equipments, to estimate the demand factor and load factor being held, and to evaluate the efficiency of electical uses for the recently electrified farms cultivating paddy rice. For the purposes, 109 sample farms located in eleven villiages electrified in six different years from 1968 to 1973, were chosen at random and investigated on 35 items concerning to electrical uses and wiring systems. The survey was carried out in 1975, in the vinicity of Suweon city. The results are summarized as follows: i) The average annual power consumption on sample farms is considered to be low, being 242.9 Kwh. in 1974, and varied according to the different electrified year and size of cultivated land, respectively. It has significant positive correlation to the area of farm, too. ii) Between the number of year of electrical uses and the power consumption, there is very significant positive correlation, which could be expressed as Y=43.041+16.108 X, where X represents the number of years of electrical uses. The annual increment of power consumption is much greater at the beginning of the electrification than that at the later years, its average being approximately 20 percent. However, it is recommended that any estimation of long-term increments should be carefully investigated. iii) The monthly power consumption varies considerably throughout a year, in which the heaviest farm load occurs in November. Observing the seasonal variation of consumption, the winter-time is the heaviest season while the summer is the lowest. The result implies house lighting is chief contribution to the present electrical consumption on the farms. Comparing the variation of monthly consumption ratios between the sample farms and industries, the electrical uses on the farms are independant of the industrial uses, and further, the agricultural uses are of inverse pattern to the farms from the results that there is negative correlationship between them, iv) The number of electrical equipments used on the farms are occupied chiefly by lighting sources. Next to the lighting sources, household appliances of small quantity and some motors are used. The mean electrical quantity is about 1, 127.4 watt, which corresponds to about 37.6 per cent to the contracted quantity. The composition of quantity is chiefly occupied by the electrical motor of about 1.5 hp., single-phased. The number of the annual utilization hours of each equipment is tabulated in Table IV-5. In contradiction to the high utilization of lighting sources and small household appliances, the motor is poorly used for approximately 22 hours in a year. v) More than 55 per cent of farms want to purchase new electrical equipments such as small household appliances and electrical motors in their number. The impulse of purchasing such items is stimulated by the contacts to the mass media and their knowledge on such equipments. Consequently, the increase of electrical uses could be prompted by such trials as education and demonstration. vi) The demand and load factors on the farms vary considerably according to the greater variation of the power consumption, daily or monthly. The daily demand factor is 22.4 per cent and load factor 18.6 per cent, while the annual demand factor is 1.3 per cent and load factor 70 per cent approximately. Therefore, the low efficiency of construction cost requires re-evaluation of the present contracted quantity of 3 Kw. or increase of electrical uses. vii) The electrical energy on the farms devoted chiefly to lighten the farm residences does not contribute to the farm incomes. Consequently, the cost of electrical consumption presses considerably upon the farm economy. Therefore, there is great need to build up the electrical uses on the farms through the development of new works and techinques to utilize any electrical equipments on the production of farm products. Further more, such the development should be related to increase the actual income of the farm consumers.

• Korean Journal of Poultry Science
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• v.28 no.2
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• pp.91-98
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• 2001

Three experiments were conducted to investigate the Pine Bark Spent Liquor (PBSL) inclusion, prepared by alkaline sulfite-anthraquinone cooking, on Pellet durability index (PDI) of practical diets and performance of broiler chicks and laying hens. Fourteen treatments with four replications were assigned for PDI test in Experiment 1. Control, 10% Wheat(W10), 20% Wheat(W20), 0.25, 0.50, 1.00, 2.00 and 3.00% PBSL, 0.1, 0.2% commercial pellet binder A(CPB A) or B(CPB B), W10 plus 0.1% CPB A or B were used for PDI test. PDI was measured by PDI tester (Oriental Motors, Japan). The control diet was based on corn and soybean meal with no wheat or pellet binders inclusion. The PDI of the PBSL or other commercial pellet binder treatments were significantly higher than control groups(P<0.05). It was shown 95.9, 95.9, 95.8, and 95.7 in W10, 0.5% PBSL, 0.2% CPB A or B treatments, respectively. Thus, those treatments were applied to Experiments 2 and 3. In experiment 2, 200 male broiler chicks (Cobb$\times$Cobb) were allocated to the control, W10, PBSL 0.5%, 0.2% CPB A and B with four replications. Starter diets contained 3,169, 3,149 kcal/kg ME and 21% CP, and finisher diets were fed at the level of 3,192, 3,172 kcal/kg ME and 19W% CP. Weight gain, feed intake, feed conversion ratio (FCR) were weekly measured for 5 wk and the number of intestinal anaerobes were examined at the end of experiment. The weight gain of chicks fed PBSL was not significantly greater than control groups, but was significant different compared to that of W10 or 0.2% CPB A treatments (P<0.05). FCR of chicks treated with PBSL or other pellet binders tended to improve compared to that of control.

• Journal of the Korean association of regional geographers
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• v.4 no.1
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• pp.77-98
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• 1998

In general, spatial imbalance in regional growth is a major cause of social and political conflicts within a state. In Korea, this inequality has functioned as a threat to the state's integration. With the economic development policies by regional industrialization over the past three decades, most of the industrial activities have been concentrated in Seoul and Pusan metropolitan areas, which are surrounded by Kyonggi, Kyongnam provinces respectively. Compared to these areas, Chonnam and Chonbuk provinces have lagged behind in economic development. Therefore, in order to increase the regional economic development of the southwestern region in Korea, the central government has been enforcing several policies aimed at regional industrialization since the 1980s. The purpose of this study focuses on the regional economic impacts of a newly established industrial estate-Yulchon industrial complex- which would act as a regional growth center in the Kwangyang bay area. The Kwangyang bay area consists of several industrial estates such as Kwangyang Iron and Steel Co. and its related industrial complex, Chuam rural industrial estate, Yeochon industrial complex, and so on. In addition, the Kwangyang container port was constructed in 1997. The Kwangyang bay area has been changing to a new industrial district in the southwestern part of Korea as a result of industrialization policies which were activated by central government. The Yulchon industrial complex, which is expected to be completed in 2001, would draw many manufacturing plants. For example, Hyundai Motors Co. has a plan to locate a new automobile assembly plant within the estate. As the plan has high probability to be realized, it will be interesting to study the effects a new automobile assembly plant and its related production linkages have on the region. This study is to estimate the expected structural characteristics of automobile production activities in Yulchon. The following details will be discussed: the regional economic impacts of a new automobile industry in Yulchon industrial complex, the production linkage formation via hierarchical subcontracting systems, the alternative strategies to promote the growth of regional economies, and the scheme to improve the auto-parts and components industry in Kwangju and Chonnam provinces by establishing auto-mobile production function. Automoblie industry generally gives great influences on not only regional economies but the related industries, for example, the firms producing automotive components. If a new plant producing automobiles and its related firms producing components are to be established in Yulchon, they will affect on the regional development directions and change the regional characteristics of industrial structure. In order to increase the spread effects of the new industry in Yulchon industrial complex, almost all of the automobile production processes must be organized concurrently within a limited range of distance. There is an imperative that the co-operation system should be structured between the assembly firm and many firms producing its components. In addition to those, it would be required such as the effective division of labors between the firms, much more capabilities in the technical innovations, and the reconstruction of interrelationship between the labor unions and the firms' managers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.697-703
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• 2023

As a part of the global industrial efforts to reduce environmental pollution owing to air pollution, regulations have been established by the International Maritime Organization (IMO). The IMO has implemented various regulations such as EEXI, EEDI, and CII to reduce air pollution emissions from ships. They are also promoting measures to decrease the power consumption in ships, aiming to conserve energy. Most of the power used in ships is consumed by electric motors. Among the motors installed on ships, the engine room blower that takes up a significant load, operates at a constant irrespective of demand. Therefore, energy savings can be expected through frequency control. In this study, we demonstrated the efficacy of energy savings by controlling the frequency of the electric motor of the generator blower that supplies combustion air to the generator's turbocharger. The system was modeled based on the output data of the turboharger outlet temperature in response to the blower frequency inpu. A PI control system was established to control the frequency with the target being the turbocharger outlet temperature. By maintaining the turbocharger design standard outlet temperature and controlling the blower frequency, we achieved an annual energy saving of 15,552kW in power consumption. The effectiveness of energy savings through frequency control of blower fans was verified during the summer (April to September) and winter (March to October) periods. Based on this, we achieved annual fuel cost savings of 6,091 thousand won and reduction of 8.5 tons of carbon dioxide, 2.4 kg of SOx, and 7.8 kg of NOx air pollutants on the training ship.