• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.1
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• pp.79-92
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• 2011

In this study, wave pressure of short-period gravity waves and tsunami acting on the upright section of the horizontal-slit type caisson placed on the impermeable or permeable seabed, which is a well-known permeable breakwater with a good wave controlling ability, are investigated via numerical simulations. Further, the permeable seabed was modeled as the porous media with porosity of 0.4. Using the numerical results, the effects of the seabed conditions on the wave pressure on the front wall and inside wall of the chamber have been studied. In the numerical simulations, short-period gravity waves and tsunami(solitary wave or bore) with the same amplitude to the gravity wave are considered. A numerical wave tank is used, which is able to consider a gas-liquid two-phase flow in the same calculation zone. Numerical results show that the wave pressure of the tsunami was 3~5 times higher than the short-period gravity waves acting on the front wall and it was 2~4 times higher than the short-period gravity waves acting on the inner wall.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.2
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• pp.83-87
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• 2017

This study was conducted to determine types of oxygen transmission rate (OTR) films suitable for modified atmosphere (MA) storage treatment of strawberries (cv. 'Maehyang') for export and examination related changes in quality of strawberries during simulated shipping distribution conditions ($2^{\circ}C$ for $10days{\sim}8^{\circ}C$ for 11 days). Strawberries were packed by 1,300, 10,000, 20,000, and $30,000cc/m^2{\cdot}day{\cdot}atm$ OTR films for MA storage treatment and perforated film as the control for MAP. Fresh weight loss rate was less than 0.5% in OTR films except for the perforated film. Carbon dioxide and oxygen content in packages prevailed in permissible range for strawberries under recommended CA/MA conditions (i.e., $CO_2$: 15~20%, $O_2$: 5~10%) at 10,000 cc, 20,000 cc, and 30,000 cc OTR films. Ethylene content in OTR films did not reveal significant differences during storage. The 1,300 cc OTR film revealed highest off-flavor and lowest fungal incidence rate by sensory evaluation. The firmness, soluble solids, and visual quality were preserved the highest at 10,000 cc OTR film. In conclusion, 10,000 cc OTR film preserved the highest quality and extended shelf-life by 13 days if compared with conventional distribution conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.712-721
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• 2017

Recently, the intensity and frequency of floods has increasing worldwide, and flood disasters have become a big problem. Flood disasters, which account for the largest portion of disasters, are floods accompanied by typhoons and localized heavy rainfall. As a result, they cause damage of levee overtopping, in which the water level of a river rises to the levee crown. Therefore, countermeasures are essential and necessary because of the damage to the facility itself as well as to life and other property. The damage magnitude depends on the collapse of the levee. A levee that is difficult to collapse will reduce the discharge inland significantly. Accordingly, the protection of the inland slope, where the collapse of the levee is initiated, is one of the most important countermeasures In this study, revetments with various porosity and forms were suggested and hydraulic experiments were carried out for each type. The hydraulic experiments showed that the stability of a revetment in an inland slope is strongly correlated with the weight per unit area of the revetment. The relationship between the critical velocity, which is the velocity at the moment of leaving the revetment, and the weight per unit area was derived. Through this study, by applying the nature friendly revetment, which has not yet been applied to Korea, it is expected that life and property damage caused by levee overtopping during flooding can be reduced, and a nature friendly river space can be constructed.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.319-324
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• 2008

The sweet pepper (paprika) is one of the most important exported vegetable crops in Korea. This study evaluated the storability of sweet pepper fruits between 2 cultivars with different maturities under different storage conditions. The sweet peppers ('Special' and 'Fiesta') were grown in a rockwool hydroponic system, and harvested two different maturities: half-maturity and full-maturity levels. The sweet pepper fruits were stored in MA(non-ventilated) and non-MA(ventilated) conditions at 4 and $9^{\circ}C$ for 20 days. The storability of sweet pepper fruit was the highest in $4^{\circ}C$ MA conditions that remained 5% carbon dioxide and 10% oxygen during the storage. The ethylene concentration in MA condition showed $2{\sim}8{\mu}l/l$ regardless of storage temperatures, cultivars and maturities. The fruits packaged with non-ventilated film, showed lower weight loss, and higher firmness, and there was no different about decay ratio compared to the fruits packed ventilated film. The coloration of semi-matured fruit that colored 50% before storage progressed faster in non-ventilated packaging condition at $9^{\circ}C$, but their color did not changed as same as level of full-matured fruit. The electrolyte leakages and respiratory rate that estimated degree of chilling injury was highest in non-MA(ventilated) conditions of 'Special' full matured fruit placed at room temperature for 3 days following storage at $4^{\circ}C$ for 20 days. It may be suggested that sweet pepper fruit packed sealed (non-ventilated) film and stored at non-chilling temperature can be maintained better quality for long term storage.

• Korea lubricating oil industries association bulletin
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• no.18
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• pp.12-22
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• 1986

국내정유산업의 후방부문인 윤활유사업은 산업의 발전과 함께 국내 진출, 다국적석유기업에 의하여 원료 및 첨가제의 공급에 의한 단순생산과 마아케팅을 하여 국내시장을 지배하여 왔다. 또한 중화학공업의 발달과 함께 산업기계에 요구되는 윤활유제품도 다양화와 품질고급화로 시장구조가 점점 변화되고 있다. 국내윤활유총생산량중 65$\%$의 시장을 가지고 있는 고급윤활유시장은 4개 제조회사에 의하여 96$\%$의 시장을 유지하고 있다. 각 제조회사의 시장확대정책에 의하여 각대리점에 대한 유통경로의 관리가 중요 마아케팅전략음 되고 있는 실정이다. 제조회사의 대형 소비자에 대한 직매, 직영대리점, 일반대리점에 대한 유통기구중 많은 판매비중을 차지하고 있는 일반대리점에 대하여 4P를 기준하여 대리점측 입장에서 마아케팅 믹스를 분석하였다. 제조회사가 판매대리점에 취하는 마아케팅 전략중 직접적인 방법과 간접적인 방법이 시장관리에 나타나는 갈등정도를 가설로 설문지를 작성하여 6월 10일부터 6월 19일까지 경인지역은 조사원에 의한 직접방문과 지방은 등기우편에 의하여 50개 일반대리점에 송부하여 60$\%$의 회수율을 보였다. 응답자료를 통하여 제조회사의 직접적인 시장관리방법과 간접적인 시장관리방법을 사용시 일반대리점에 대한 갈등해소 정도를 상관분석을 통한 통계처리를 하였다. 본 연구결과는 다음과 같은 사실을 얻을수 있었다. 제조회사가 일반대리점에 실시하는 직접적 또는 간접적인 시장관리는 일반대리점에 대하여 갈등해소에 커다란 작용을 하지 못한다. 따라서 제조회사는 유통경로에 대한 전략을 첫째, 일반대리점과 직영대리점과의 시장에 대한 마찰해소 둘때, 대리점에 대한 안정적인 판매이윤제공 셋째, 계획적인 판매대리점간 시장경쟁조정 넷째, R & D 투자강화로 제조회사 차원에서 공동으로 산학협동하여 첨가제 및 상표의 국내개발을 이루어 제품가격인하로 장기적인 시장개발이 요청된다는 결론을 얻었다.

• Journal of Drive and Control
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• v.13 no.3
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• pp.8-14
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• 2016

This study describes the effect of the critical pressure ratio of a control valve on the performance of an air spring system composed of an air spring, auxiliary chamber, control valve and mass in order to suggest a more efficient design for an air spring system. The critical pressure ratio of the control valve is assumed to have a fixed value, but the critical pressure ratio of the control valve is known to have various values between 0.05 and 0.6, and the effect of the variation of the critical pressure ratio on the performance of the air spring system has not yet been reported. The analysis derives nonlinear and linear governing equations of the air spring system, including the critical pressure ratio of the control valve. This simulation study is presented to show that the impedance and transmissibility characteristics of the air spring system change due to variations in the critical pressure ratio of the control valve as well as its sonic conductance. As a result, the critical pressure ratio of the control valve should be maintained as large as possible to improve the vibration isolation characteristics of the air spring system.

• Journal of Drive and Control
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• v.14 no.2
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• pp.16-22
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• 2017

This paper presents the algorithm of an adaptive model-free-control-based steering control for multi-axle all-terrain cranes for which the recursive least squares with forgetting are applied. To optimally control the actual system in the real world, the linear or nonlinear mathematical model of the system should be given for the determination of the optimal control inputs; however, it is difficult to derive the mathematical model due to the actual system's complexity and nonlinearity. To address this problem, the proposed adaptive model-free controller is used to control the steering angle of a multi-axle crane. The proposed model-free control algorithm uses only the input and output signals of the system to determine the optimal inputs. The recursive least-squares algorithm identifies first-order systems. The uncertainty between the identified system and the actual system was estimated based on the disturbance observer. The proposed control algorithm was used for the steering control of a multi-axle crane, where only the steering input and the desired yaw rate were employed, to track the reference path. The controller and performance evaluations were constructed and conducted in the Matlab/Simulink environment. The evaluation results show that the proposed adaptive model-free-control-based steering-control algorithm produces a sound path-tracking performance.

• Journal of Drive and Control
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• v.11 no.2
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• pp.30-35
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• 2014

The pumps of electro-hydrostatic actuators operate most frequently in boundary lubrication speed range, as they compensate for the position control errors as a control element. When conventional swash plate type piston pumps are applied to electro-hydrostatic actuators, the frictional power losses as well as the wear rate of sliding components, such as piston shoes can increase drastically under the boundary friction condition. In this paper, the power losses of the piston shoes were investigated which were engendered by a frictional solid-to-solid contact and leakage flow rate of their hydrostatic bearing. In order to reduce them, DLC-coating was applied to the swash plate and the ball joint of pistons along with its effects were demonstrated. In addition, it was also shown that the wear rate of the piston shoes could be markedly reduced using the DLC-coated swash plate.

• Health Policy and Management
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• v.31 no.1
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• pp.35-45
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• 2021

Background: As a descriptive study targeting 2,068 cancer patients as men of national merit in 2013, this study aims to provide the basic data for systematizing the early diagnosis and treatment of cancer by comparatively analyzing the 5-year survival rate. Methods: This study researched the survival of cancer patients through Electronic Medical Record and Patriots-Veterans Qualification Program, targeting 2,068 newly-diagnosed cancer patients verified in five veterans hospitals and consigned management system. This study verified differences between general characteristics of cancer patients as men of national merit and analyzed their survival rate. Results: The cancer patients as men of national merit were super-aged as their average age was 72.5. In the analysis of general characteristics of five major prevalent cancers, there were statistically significant differences according to age, region, cancer diagnostic path, differentiation, diagnostic method, treatment method, SEER stage, and survival period, except for the types of the man of national merit (p<0.001). The whole survival rate of cancer patients as men of national merit was 50%. The 5-year survival rates of predisposing cancers were shown as prostate cancer (79%), colorectal cancer (64%), gastric cancer (57%), liver cancer (32%), and lung cancer (12%). In the cancer diagnostic path, all the predisposing cancers showed the highest survival rate in medical examination. In the treatment method, the surgery showed the highest survival rate. The cancer patients as men of national merit showed a lower survival rate than the general cancer patients of Korea. Conclusion: It would be needed to guarantee the honorable and happy life through health recovery as special treatment of contribution and sacrifice of super-aged men of national merit by increasing the cancer survival rates through regular checkup, early diagnosis, and high-quality treatment system that could have important effects on the survival rate according to the occurrence of cancers.

• Journal of Drive and Control
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• v.19 no.4
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• pp.36-45
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• 2022

The aim of this study was to verify an E-driving system of a 44 kW-class electric tractor using agricultural workload data. Workload data were acquired during field test (plow tillage, rotary tillage, loader operation, field driving, asphalt driving) using a conventional tractor with a load measurement system. These workload data were converted to data of a 44 kW-class tractor based on the load factor of the engine. These data were used to verify the design of the E-driving system of an electric tractor. High-load operations such as plow tillage, rotary tillage, and loader operation could be performed at stage L and stage M. High-speed operation (asphalt driving) could be effectively performed at stage H using a rated rotational speed of the motor. As a result, the E-driving system of the electric tractor was possible to perform all major agricultural operations according to gear stages of range shift. Based on results of this research, we plan to develop an electric tractor equipped with an E-driving system and conduct research on actual vehicle verification in the future.