• Journal of the Society of Naval Architects of Korea
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• v.61 no.4
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• pp.258-266
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• 2024

It is necessary to predict the ship's manoeuvrabilities in waves for its safe operations in adverse weather. At the early design stage, free-running model tests can be performed to estimate the ship's manoeuvring performance in irregular wave conditions. The wave elevations are randomly varied with times in irregular waves, large deviations of the manoeuvring performance indices are likely to occur depending on the start time of steering scenarios. In this study, a KSUPRAMAX model ship's manoeuvres in long-crested irregular waves are reproduced in the equivalent regular waves. The equivalent regular waves are searched from the energy flux relations between long-crested irregular and regular waves. But there are differences of forward speeds in the model tests, regular wave height and period are modified so that both the forward speed and the trajectory drift in regular waves are similar to those in irregular waves. In addition, low speed course-keeping tests are performed with various wave incident angles in irregular and regular waves. It is confirmed that check helms, drift angles, and speeds as well as trajectories in irregular waves are similar to those in equivalent regular waves.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.127-134
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• 2024

With the growth of offshore wind power generation market, the corresponding installation vessel market is also growing. It is anticipated that approximately 100 installation vessels will be required in the of shore wind power generation market by 2030. With a price range of 300 to 400 billion Korean won per vessel, this represents a high-value market compared to merchant vessels. Particularly, the demand for large installation vessels with a capacity of 11 MW or more is increasing. The rapid growth of the offshore wind power generation market in the Asia-Pacific region, centered around China, has led to several discussions on orders for operational installation vessels in this region. The seabed geology in the Asia-Pacific region is dominated by clay layers with low bearing capacity. Owing to these characteristics, during vessel operations, significant spudcan and leg penetration depths occur as the installation vessel rises and descends above the water surface. In this study, using penetration variables ranging from 3 to 21 m, the unique vibration period, structural safety of the legs, and conductivity safety index were assessed based on penetration depths. As the penetration depth increases, the natural vibration period and the moment length of the leg become shorter, increasing the margin of structural strength. It is safe against overturning moment at all angles of incidence, and the maximum value occurs at 270 degrees. The conditions reviewed through this study can be used as crucial data to determine the operation of the legs according to the penetration depth when developing operating procedures for WTIV in soft soil. In conclusion, accurately determining the safety of the leg structure according to the penetration depth is directly related to the safety of the WTIV.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.789-797
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• 2021

The worldwide sizes of container ships are rapidly increasing. The container ship size in 2005, which was about 9,200 TEU has increased to 24,000 TEU in recent times. In addition to the increase in the sizes of the container ships, the arrivals/departures of large container vessels to/from Korea have also increased. Hence, the necessity for reviewing safe passage of such vessels is emphasized. In the present study, a 24,000 TEU container vessel was used as a model ship to calculate the under-keel clearance (UKC) at Gadeok Channel through which vessels must pass to arrive at Busan New Port, in accordance with the Korean Port and Fishing Port Design Standards and Commentary. In addition, the maximum allowable speed that meets UKC standards was calculated using various squat formulas, whose results were then compared with the current speed limit standards. The analysis results show that Busan New Port requires 10% marginal water depth, and the squat that meets this requirement is 0.95 m. Gadeok Channel requires 15% marginal water depth, and the squat that meets this requirement is 1.78 m; in this case, the maximum allowable speed is calculated as 15 kts. Busan New Port has set the speed limit as 12 kts, which is higher than the calculated 11 kts. Thus, speed limit reconsideration is required in terms of safety. However, the set speed limit for Gadeok Channel is 12 kts, which is lower than the calculated 15 kts. Thus, additional considerations may be provided to increase the speed limits for smooth navigational passage of vessels. The present study, however, is constrained by the fact that it reflects only a limited number of elements in the UKC and allowable speed calculations; therefore, more accurate UKC and safe speed values can be suggested based on extended studies to this research.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.189.2-189.2
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• 2010

The purpose of this study is fatigue damage assessment for large sized casting parts (hub and mainframe) of the 3MW offshore wind turbine by computer simulation. Hub and mainframe durability assessment is necessary because wind turbine have to guarantee for 20 years. Fatigue life evaluation must be considered all of fatigue load conditions as the components are wind load transmission path. Palmgren-Miner linear damage accumulation hypothesis is applied for fatigue life estimation with stress-life approach. S-N curve for the spheroid graphite cast iron EN-GJS-400-18-LT is derived according to durability guidelines. Reduction factors were applied for survival probability, surface roughness, material quality and partial safety factor according to Germanischer Lloyd rules. To calculate fatigue damage, stress tensors, extracted from the unity load calculation from ANSYS is multiplied with time track of fatigue loads extracted from GH bladed. Damage accumulation is performed with all of fatigue load conditions at each finite element nodes. In this study maximum nodal damage value is under 1.0. casted parts are safe. This research was financially supported by the Ministry of Knowledge Economy(MKE), Korea Institute for Advancement of Technology(KIAT) and Honam Leading Industry Office through the Leading Industry Development for Economic Region.

• Journal of East-West Nursing Research
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• v.23 no.1
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• pp.75-85
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• 2017

Purpose: This study was conducted to examine the effects of Pericardium Kimek (K9) and Nei-Guan (P6) acupressure on relief of the anxiety, nausea, retching and physiologic changes (oxygen saturation, blood pressure, heart rate, temperature and respiration) in the patients undergoing unsedated esophagogastroduodenoscopy. Methods: A quasi-experimental research design was used. The participants were assigned into the listed three groups, i.e., the control group, the first experimental group (E1: K9 acupressure group) and the second experimental group (E2: P6 acupressure group). A total of 60 participants were included for analysis. Results: The severity of nausea (F=3.503, p=.037), the oxygen saturation (F=5.417, p=.007). and the respiration rate (F=7.270, p=.002) showed statistically significant differences in three groups. Conclusion: Based on the results of the present study, K9 acupressure with moxa pellets and P6 acupressure with wristbands (Sea-Band) are considered to be safe and an easy-to-apply intervention to relieve nausea and maintain the level of oxygen saturation and respiration rate in patients undergone unsedated esophagogastroduodenoscopy.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.862-870
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• 2016

AIS and V-PASS, which are used for safe navigation and automatic vessel arrival and departure, are mandatory standard equipment installed on all ships. If an aircraft is equipped with a ship identification system using AIS and V-PASS, and then ship identification information is received by a vessel such as a large fishery inspection boat or a patrol ship or a ground control system, we can quickly perform maritime surveillance and disaster response. This paper describes the development of a ship identification and display system using a ship identification device for aircraft. Flight test results and a future application plan are also included.

• Korean Journal of Head & Neck Oncology
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• v.16 no.1
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• pp.37-41
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• 2000

Background and Objectives: The most commonly used incision for parotidectomy is modified Blair incision, but it has unsatisfactory cosmetic result due to long exposed scar in the neck. Therefore, we introduce an alternative approach with more acceptable scar named modified facelift incision. We report it's techniques, indications and disadvantages with our experiences. Materials and Methods: During the 1999, 15 patients were underwent parotidectomies using modified facelift incision. We studied the postoperative complications and the cosmetic results respectively. Results: There were 11 benign tumors, 3 malignant tumors, and 1 chronic inflammation. Total parotidectomy was performed in 2 malignant tumors and chronic parotitis patients. The others has superficial parotidectomy. In terms of operation field, there was no difference between classical incision and facelift incision. Partial facial nerve palsy was noted in 2 cases, who required sacrifice of branches of facial nerve because of malignant tumor invasion. There were no specific complications associated with this type of approach. Postoperative cosmetic results were satisfactory in all cases. Conclusion: Modified facelift incision provides better cosmetic result than conventional incision without narrowing of operation field. We believe that it is a safe alternative approach to all parotidectomy cases especially to women and patient with keloid skin. The only limitation of this incision is poor adaptability for combining neck dissection.

• Convergence Security Journal
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• v.1 no.1
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• pp.9-20
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• 2001

In the 3rd Wave of information revolution, technical research & development for more rapid and safe information exchange take a sudden turn currently According to a step up in importance and efficiency value of information, it's necessary to research technical development in various field altogether. Especially information security is the very core of essential technology. However most System attacks are based on the weakness of OS, it is difficult to achieve the security goal in the only application level. For the solution of this problem, so many technology researches to serve secure, trust information security in OS itself are activated. Consequently we introduce the tendency of current secure OS development projects of security kernel all over world in this report and inquire into security mechanism of the File Griffin which prevents file system forgery, modification perfectly by performing digital signature certificate on kernel level.

• Journal of Energy Engineering
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• v.5 no.2
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• pp.146-152
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• 1996

A small power reactor core of 108 MW$\_$th/ was designed with some design constraints: 2 year refueling cycle length, soluble boron free operation, low power density, and proven fuel assembly design - Uljin 3'||'&'||'4 design specifications. CASMO-3 and KINS-3 was used to evaluate operational capability for power level control via control rods. Cycle length, power peaking factor, M.T.C., and power coefficients were also checked. Designed core loaded with KOFAs satisfied all design goals. We found that much more burnable poisons are to be loaded with axial enrichment zoning. Control rod assemblies should be located at every other assemblies with more than 3 banks. Additional shutdown banks are proposed for the safe plant cooldown, which could be located at core periphery.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.10 no.1
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• pp.35-44
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• 2002

Inertial Navigation System(INS) has been used in the field of air navigation for a long time but is not popular in general aviation due to high price. Recently low-price GPS is available but vulnerable to radio interference. As an alternative on these problems, GPS/INS integrated navigation system has been considered. GPS/INS is capable of implementing navigation with low-price inertial sensors but its accuracy is dependent upon how much drift of INS may be calibrated by using GPS. In order to apply GPS/INS to air navigation, it must be investigated how long drift of INS in case of no GPS aiding will be bounded within requirements for safe flight. From the above motivation, the flight test for GPS/INS navigation system was conducted in order to make sense its performance in air navigation and its result was shown.