• Journal of Korea Port Economic Association
• /
• v.26 no.3
• /
• pp.221-239
• /
• 2010

This study aims to provide solutions concerned with to residential moving companies about their operational problems. In order to shed light on these problem, factor analysis and fuzzy AHP method are adopted. Selected factors are low quality of workers and equipments, weak condition of business, policy and form of a contract, and excessive competition. The results of survey show that excessive competition is the most urgent problem compared with other problems. In the twelve-measured variables, The problem of non-certificated firms, low service quality caused by excessive competition, and claims caused by lack of service instruction are chosen as the urgent matters. As a result of the analyses, the study would propose policy directions how to solve these problems. Firstly, the government should make the legal basis of operating the industry because there is too competitive in the field. Secondly, the government should regulate firms which have not a certificate because they are the cause of low service quality in the field. Thirdly, in order to improve the service quality, the study would suggest that the managers should instruct the workers of residential moving companies. Lastly, the paper would suggest that customers check the certificate of the firm allowed by the government authorities.

• Journal of Broadcast Engineering
• /
• v.14 no.6
• /
• pp.721-732
• /
• 2009

AT-DMB system has been developed to increase data rate up to double of conventional T-DMB in same bandwidth while maintaining backward compatibility. The AT-DMB system adopted hierarchical modulation which adds BPSK signal or QPSK signal as enhanced layer to existing DQPSK signal. The enhanced layer signal should be small enough to maintain backward compatibility and to minimize the coverage loss of existing T-DMB service area. But this causes the enhanced layer signal of AT-DMB susceptible to fading effect in transmission channel. A turbo code which has powerful error correction capability is applied to the enhanced layer signal of the AT-DMB system for compensating channel distortion. We developed the prototype AT-DMB transmitter and receiver systems for performance evaluation. LAB test for analysing the effect of constellation ratio between existing base layer signal and enhancement layer signal, was conducted and the measurement results are shown with analysis comments.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.143-143
• /
• 2011

4대강 살리기 사업에서 국가하천 주요 구간에 대규모 보가 건설되고 있다. 이로 인해 치수 및 하천환경에 많은 문제점이 야기될 수 있으며, 발생 가능한 하천관리의 문제점을 최소화하기 위해서는 하천정비에 따른 수리학적 영향을 검토할 필요가 있다. 보의 설치는 유지유량 및 수심 확보의 목적을 지니고 있지만, 기존 하천에 설치된 보는 대부분 고정보로서 흐름의 정체를 유발시키는 단점이 있다. 최근에는 가동보가 설치되어 일정 이상의 초과 유량 및 수위를 조절할 수 있도록 탄력적인 보 운영이 이루어지고 있다. 본 연구에서는 낙동강 본류에 건설 중인 강정보 설치지점 직상 하류 구간에 대하여 가동보의 설치 및 운영에 따른 보주변의 흐름특성을 RMA2와 FLOW-3D를 이용하여 모의하였다. 2개의 수문으로 구성되어 있는 강정보의 수문 운영을 2년 빈도 및 100년 빈도 홍수량에 대하여 좌측 또는 우측 단일수문 완전개방 및 부분개방, 양측 수문의 완전개방 및 부분개방에 따른 보 상류단 수위의 변화 및 하류단에 형성되는 주흐름의 변화를 분석하였다. 2년 빈도 홍수량에서의 가동보 지점의 유속이 100년 빈도 홍수량에 대한 가동보 지점의 유속보다 크게 발생하였다. 양측 수문을 완전히 개방하였을 때 주흐름이 우안방향으로 휘는 현상이 발생하였으며, 우측 수문 단일개방에서 주흐름의 우측 휨 현상이 뚜렷이 나타나고 있어 양측 수문 개방에서의 주흐름이 우측 수문에서 발생되는 흐름에 의해 지배되고 있는 것으로 판단된다. 100년 빈도 홍수량에 대한 모의에서 수문 개방방식에 따른 보 상류부의 홍수위 변화가 크게 나타나지 않았으며, 2년 빈도 홍수량에서는 수문 개방 방식에 대한 보상류의 수위가 차이를 보였다. 가동보의 $30^{\circ}\sim60^{\circ}$ 부분개방에 대한 모의결과에서는 부분개방의 정도가 커짐에 따라 수문 지점에서의 유속이 크게 발생하였다.

• Journal of Korea Society of Industrial Information Systems
• /
• v.20 no.6
• /
• pp.29-36
• /
• 2015

This paper presents an LED backlight driver IC consisting of three linear current regulators and an output-voltage regulation loop with a self-adjustable reference voltage. In the proposed LED driver, the output voltage is controlled by dual feedback loops. The first loop senses and controls the output voltage, and the second loop senses the voltage drop of the linear current regulator and adjusts the reference voltage. With these feedback loops, the voltage drop of the linear current regulator is maintained at a minimum value, at which the driver efficiency is maximized. The output of the driver is a three-channel LED setup with four LEDs in each channel. The luminance is adjusted by the PWM dimming signal. The proposed driver is designed by a $0.35-{\mu}m$ 60-V high-voltage process, resulting in an experimental maximum efficiency of approximately 85%.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.5
• /
• pp.376-383
• /
• 2022

The improved performance of computer parts, such as graphic card, CPU, and main board, has led to the need for power supplies with a high power output. The dynamic load profile rapidly changes the usage of power consumption depending on load operations, such as PC power and air conditioner. Under dynamic load profile conditions, power consumption can be classified into maximum, normal, and standby power. Several problems arise in the case of maximum power. Peak power is generated at the system power source in the maximum-power situation. Frequent generation of peak power can cause high-frequency problems and reduce the life of high-pressure parts (especially high-pressure capacitors). For example, when a plurality of PCs are used, system overload occurs due to peak power generation and causes problems, such as power failure and increase in electricity bills due to exceeded contract power. To solve this problem, a system peak power limit/compensation power circuit is proposed for a power supply under dynamic load profile conditions. The proposed circuit detects the system current to determine the power situation of the load. When the system current is higher than the set level, the circuit recognizes that the system current generates peak power and compensates for the load power through a converter using a super capacitor as the power source. Thus, the peak power of loads with a dynamic load profile is limited and compensated for, and problems, such as high-frequency issues, are solved. In addition, the life of high-pressure parts is increased.

• The KIPS Transactions:PartB
• /
• v.13B no.2 s.105
• /
• pp.105-114
• /
• 2006

In ubiquitous environment where various kinds of computers are embedded in persons, objects and environment and they are interconnected and can be used in my place as necessary, different types of data need to be exchanged between heterogeneous machines through home network. In the environment, the efficient processing, transmission and monitoring of image data are essential technologies. We need to make research not only on traditional image processing such as spatial and visual resolution, color expression and methods of measuring image quality but also on transmission rate on home network that has a limited bandwidth. The present study proposes a new motion vector estimation algorithm for transmitting, processing and controlling image data, which is the core part of contents in home network situation and, using algorithm, implements a real time monitoring system of multi dimensional images transmitted from multiple cameras. Image data of stereo cameras to be transmitted in different environment in angle, distance, etc. are preprocessed through reduction, magnification, shift or correction, and compressed and sent using the proposed metamorphosis hierarchical motion vector estimation algorithm for the correction of motion. The proposed algorithm adopts advantages and complements disadvantages of existing motion vector estimation algorithms such as whole range search, three stage search and hierarchical search, and estimates efficiently the motion of images with high variation of brightness using an atypical small size macro block. The proposed metamorphosis hierarchical motion vector estimation algorithm and implemented image systems can be utilized in various ways in ubiquitous environment.

• Journal of Korean Ophthalmic Optics Society
• /
• v.16 no.4
• /
• pp.409-415
• /
• 2011

Purpose: To design applied anamorphic lens that focal length ratio is 3:1 optical system to improve detecting distance. Methods: We defined a boundary condition as $50^{\circ}{\sim}60^{\circ}$ for viewing angle, horizontal direction 36mm, vertical direction 12 mm for focal length, f-number 4, $15{\mu}m{\times}15{\mu}m$ for pixel size and limit resolution 25% in 33l p/mm. Si, ZnS and ZnSe as a materials were used and 4.8 ${\mu}m$, 4.2 ${\mu}m$, 3.7 ${\mu}m$ as a wavelength were set. optical performance with detection distance, narcissus and athermalization in designed camera were analyzed. Results: F-number 4, y direction 12 mm and x direction 36 mm for focal length of the thermal optical system were satisfied. Total length of the system was 76 mm so that an overall volume of the system was reduced. Astigmatism and spherical aberration was within ${\pm}$0.10 which was less than 2 pixel size. Distortion was within 10% so there was no matter to use as a thermal optical camera. MTF performance for the system was over 25% from 33l p/mm to full field so it was satisfied with the boundary condition. Designed optical system was able to detect up to 2.9 km and reduce a diffused image by decreasing a narcissus value from all surfaces except the 4th surface. From sensitivity analysis, MTF resolution was increased on changing temperature with the 5th lens which was assumed as compensation. Conclusions: Designed optical system which used anamorphic lens was satisfied with boundary condition. an increasing resolution with temperature, longer detecting distance and decreasing of narcissus were verified.

• Progress in Medical Physics
• /
• v.26 no.4
• /
• pp.250-257
• /
• 2015

Multi-leaf collimator (MLC) systems are frequently used to deliver photon-based radiation, and allow conformal shaping of treatment beams. Many proton beam centers currently make use of aperture and snout systems, which involve use of a snout to shape and focus the proton beam, a brass aperture to modify field shape, and an acrylic compensator to modulate depth. However, it needs a lot of time and cost of preparing treatment, therefore, we developed the manual MLC for solving this problem. This study was carried out with the intent of designing an MLC system as an alternative to an aperture block system. Radio-activation and dose due to primary proton beam leakage and the presence of secondary neutrons were taken into account during these iterations. Analytical calculations were used to study the effects of leaf material on activation. We have fabricated tray model for adoption with a wobbling snout ($30{\times}40cm^2$) system which used uniform scanning beam. We designed the manual MLC and tray and can reduce the cost and time for treatment. After leakage test of new tray, we upgrade the tray with brass and made the safety tool. First, we have tested the radio-activation with usually brass and new brass for new manual MLC. It shows similar behavior and decay trend. In addition, we have measured the leakage test of a gantry with new tray and MLC tray, while we exposed the high energy with full modulation process on film dosimetry. The radiation leakage is less than 1%. From these results, we have developed the design of the tray and upgrade for safety. Through the radio-activation behavior, we figure out the proton beam leakage level of safety, where there detects the secondary particle, including neutron. After developing new design of the tray, it will be able to reduce the time and cost of proton treatment. Finally, we have applied in clinic test with original brass aperture and manual MLC and calculated the gamma index, 99.74% between them.

• Management & Information Systems Review
• /
• v.31 no.4
• /
• pp.57-82
• /
• 2012

The purpose of the study is to suggest the measure for the improvement of job satisfaction and level of empowerment of sanatoriums' social workers by analyzing factors of empowerments' effect on the job satisfaction, and investigating level of empowerment and job satisfaction of social workers of sanatoriums for the elderly and the handicapped. The result of investigation and analysis on subjects of 420 social workers of sanatoriums for the elderly and the handicapped in Youngnam area for this is as follows: First, job characteristic that is empowerments' influence factor of sanatoriums' social workers is appeared in order of feedback, and function variety, and in organization characteristic is appeared in order of leadership, reward, and employee development. Second, level of empowerment that is recognized by sanatoriums' social workers is appeared a little higher than normal level and significance is appeared highest, and next are capability, self-determination ability, and influence. Third, features that showed significant difference with significance in general characteristic of sanatoriums' social workers were 'sex', 'marital status', and 'religion', and features that showed significant difference with capability were sex, age, marital status, academic background, and employment history. And features that showed significant difference with self-determination ability were sex, age, marital status, and employment history, and features that showed significant difference with influence were sex, age, employment history and types of facilities. Fourth, the whole average of job satisfaction of sanatoriums' social workers was 3.82 out of 5, which is generally high, features that showed significant difference statistically were age, marital status, academic background, employment history, and types of facilities. Thus, job satisfaction was appeared as high as 'more than age of thirty' in age, 'married' in marital status, 'under graduates of colleges' in academic background, and 'less than three years' in employment history. Fifth, as for factors that had influence on job satisfaction, the indirect effect with empowerment was appeared that had significant effect in organization characteristic, and had few effect in organization features. On these results, practical measures to increase job satisfaction of sanatoriums' social workers are as follows: First, political approach is required to standardize duty system(by various types of facilities and clients' characteristic) of social workers of sanatoriums for elderly and the handicapped, and help to do the role as professionals with giving better treatment and building self-respect by enough reward. Second, to suggest chances to perform the responsibility for the duty of the scenes by the regular supervision, establish regular supervision system of social workers of sanatoriums for the elderly and the handicapped, and the extension of duty to increase the functional varieties. Third, it is required to motivate to have self confidence for the work and to use potential ability with transforming leadership, and to have more chances of education for the self-development. To increase job satisfaction of sanatoriums' social workers who give direct services in sanatoriums for the elderly and the handicapped, more active and positive empowerment's level improvement is in need by improvement of empowerment for them.