• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1994.04a
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• pp.43-48
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• 1994

A wide band design method of an electromagnetic wave absorber using exponentially tapered ferrite which has very wide band frequency characteristics is proposed and discussed. The wide band electromagnetic wave absorber can be designed by the proposed equivalent material constants method for the regions varying spatially in the shape of ferrite. Furthemore the wide band ferrite electromagnetic wave absorbers with taper which have not only excellent reflectivity frequency characteristics but also the band width of 30MHz to 2150 or 2450MHz under the tolerance limits of -20dB reflectivity were designed.

• Journal of Chest Surgery
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• v.47 no.4
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• pp.384-388
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• 2014

Background: Recently, single-port video-assisted thoracic surgery (VATS) has been proposed as an alternative to the conventional three-port VATS for primary spontaneous pneumothorax (PSP). The aim of this study is to evaluate the early outcomes of the single-port VATS for PSP. Methods: VATS was performed for PSP in 52 patients from March 2012 to March 2013. We reviewed the medical records of these 52 patients, retrospectively. Nineteen patients underwent the conventional three-port VATS (three-port group) and 33 patients underwent the single-port VATS (single-port group). Both groups were compared according to the operation time, number of wedge resections, amount of chest tube drainage during the first 24 hours after surgery, length of chest tube drainage, length of hospital stay, postoperative pain score, and postoperative paresthesia. Results: There was no difference in patient characteristics between the two groups. There was no difference in the number of wedge resections, operation time, or amount of drainage between the two groups. The mean lengths of chest tube drainage and hospital stay were shorter in the single-port group than in the three-port group. Further, there was less postoperative pain and paresthesia in the single-port group than in the three-port group. These differences were statistically significant. The mean size of the surgical wound was 2.10 cm (range, 1.6 to 3.0 cm) in the single-port group. Conclusion: Single-port VATS for PSP had many advantages in terms of the lengths of chest tube drainage and hospital stay, postoperative pain, and paresthesia. Single-port VATS is a feasible technique for PSP as an alternative to the conventional three-port VATS in well-selected patients.

• Journal of Navigation and Port Research
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• v.29 no.10 s.106
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• pp.821-826
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• 2005

The traffic volume will be increased and the traffic of larger vessel could be multiplied in the Pohang port by the opening of the Young-il new port in 2006. Unfortunately, however, potential danger factors to the safe navigation, disordered navigation and traffic congestion are still existing in the Pohang port and approaching waters. This paper describes the status of marine traffic flow and navigational characteristics based on the marine traffic survey using the exclusive software, and the results of marine traffic survey classify into ship's type, size and track history of passing ships through the statistical methods. Finally the examinations of marine traffic route, traffic flow and navigational characteristics are discussed. These results can be used for the best design of ship's routing at the Pohang waters.

• Proceedings of KOSOMES biannual meeting
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• 2009.06a
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• pp.89-94
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• 2009

This study aims to examine the the characteristics if the sea water circulation in related to the change of the water exchange rate according to the the development phases of Busan Port. To clarify the characteristics, the water exchange caused by construction if new-port and river discharge conditions was examined by the numerical experiments using the Lagrangian particle tracking model based on 2-D shallow water equation. This study deals with the charge of flow field and water exchange after redevelopment using numerical simulation technique, based on the field observation and 4 rivers discharge flow. As a result if numerical simulation, Variation if current velocity in Busan North Port is almost nothing before and after construction. Water exchange of channel in area of redevelopment is a little. Futhermore, the tidal exchange had a tendency to be small both before and after redevelopment by 60%.

• Journal of Navigation and Port Research
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• v.33 no.10
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• pp.743-756
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• 2009

This paper tries to analyze how the governance institutions of the Port Authority of New York and New Jersey overcome agent problems in public agencies based on the Principal-Agent Theory, and find the implications that will be helpful to the governance of port authorities in Korea. The Port Authority's governance is characterized by decentralization of personnel rights, open meetings policy, freedom of information policy, public hearings, and fiscally self-supporting system. Those characteristics are helpful in overcoming the agent problems of public agency, such as adverse selection, moral hazard, and complicated external structure, through reinforcing of monitoring agent by principal, easing of information asymmetry between principal and agent, and clarification of organizational ownership structure. Those characteristics may give many implications for the design of governance structures of port authorities in Korea.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2071-2075
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• 2003

Pressure variation is one of the major sources on noise emission in the oil hydraulic piston pumps. Therefore, it is necessary to clarify about pressure variation characteristics of the oil hydraulic piston pumps to reduce noise. Pressure variations in a cylinder at trapping region were measured during pump working period with discharge pressures, rotational speeds. The effect of pre-compression of the discharge port with three types valve plates also investigated. It was found that the pressure variation characteristics of oil hydraulic piston pumps deeply related with pre-compression design of the discharge port. Also, it was found that the pressure overshoot at trapping region can reduce by use of pre-compression at the end of the discharge port in valve plate

• Journal of Korean Port Research
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• v.12 no.1
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• pp.145-154
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• 1998

Protection characteristics of the corroded steel pile which was served as a pier structure over 8 years in seawater have been examined in terms of corrosion potential, electrochemical impedance spectroscopy(EIS) and anodic/cathodic polarization curves. The steel structure was sectioned into two parts, waterline(splash zone, just above the seawater surface) and in-water(underwater), and protection characteristics for the two parts were investigated with the application of cathodic protection(CP) by sacrificial anodes using Zn and Al alloys. The main results obtained were as follows; (1) The corrosion potential of waterline zone was higher than that of in-water, which implied that the corrosion of waterline was more severe than that of in-water, (2) As a result of EIS examination, the transition period from the apparent CP to the substantial CP took about twenty to thirty days according to the corrosion condition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.7
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• pp.417-427
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• 2016

This paper is the first investigation of the steady flow characteristics of an SI engine with a semi-wedge combustion chamber as a function of the port shape. For this purpose, the planar velocity profiles were measured at the 1.75B position by particle image velocimetry. The flow patterns were examined with both a straight and a helical port. Two swirls were observed up to 4 mm valve lift with the straight port and up to 2 mm with the helical one; however, only one swirl was present after these lifts. The flow characteristics changed suddenly between 4 and 5 mm lift in the straight port; on the other hand, the change with lift was gradual with the helical port - the transition points between flow regimes were different with the port shapes. In addition, the centers of the swirls were relatively far from the cylinder center so that the effect of eccentricity may not be negligible at 1.75B, regardless the shape. The eccentricity values with the straight port were especially high - over 0.5 for all lifts. Finally, real velocities were found to be much lower than those predicted by the assumption of ISM evaluation, with the profiles differing qualitatively as well.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.806-811
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• 2001

Since the characteristics of combustion and pollutant in Diesel engines were mainly effected by the characteristics of in-cylinder gas flow and fuel spray, an understanding of those was essential to the design of the D.I. Diesel engines. The improvement of volumetric efficiency of air charging into combustion chamber is a primary requirement to obtain better mean effective pressure of an engine. Since parameters such as the air resistances in intake and exhaust flow passages, valve lift and valve shape influence greatly to the volumetric efficiency, it is very important to investigate the flow characteristics of intake and exhaust port which develops air motion in the combustion chamber. In this study, two approach methods were used for design intake and exhaust port; experiment and computation which were made by using steady flow test rig and commercial CFD code. This paper presents the results of an experimental and analytical investigation of steady flow through the prototype cylinder head ports and valves of the HHI's H21/32 HIMSEN Engine.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.503-512
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• 2012

In Yongwon channel, its natural flow of seawater is blocked by the construction of Busan New Port including the container berth. The channel was transformed into a narrow and long one, where it is possible that ships are only allowed to pass through the north-side channel of Gyeonmado located at the point of river mouth to Songjeongcheon. In addition, Yongwon channel is approximately 100 m wide on average and 3,600 m long, and has the highest slenderness ratio (length/width = 36). So it is considered that the changes in the terrain characteristics of Yongwon channel is likely to alter the circulation of sea water, thereby changing its water quality. In this study, the bottom sediment were collected from the 48 points of the Yongwon channel and the long-term leaching characteristics were analyzed. Thus, changes in sediment and water quality were analyzed through the sediment release test to investigate the degree of contamination. The sediment release from the inside region was higher than the outer region, which is due to the pollutant that comes form the downtown area. The results of this study can be used to predict the water quality in the future and prepare the economically optimized countermeasures to improve the water quality of Yongwon channel, Busan New Port.