• Journal of Navigation and Port Research
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• v.30 no.5 s.111
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• pp.415-420
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• 2006

Urinalyses have been conducted for 28 crew's in H University's training ship and creatine and uric acid turned out to be higher in all ages, which can be inferred that board job has caused negative impact on kidney and/or malfunction In addition, TC and HDL-C, LDL-C ha; decreased, however, TG has increased after the navigation. All different positions including officer, crew, decker, engineer and radio part showed the similar pattern TC and HDL-C has decreased in 30s, 40s and TG has increased in 30s. A few of the 30's show extremely high TG rates so hyperlipidemia is suspected. 7 members turned out positive for UBG test and 5 positive for PRO test. Especially there was only one UBG positive before the navigation but, 7 members has become positive, which means the one-month long-tenn navigation has definite impact on the liver cell function.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.538-548
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• 2016

The purpose of this study is to identify the possibility of effective tuning works, understand the characteristics of tuning engine, and analyse the basic data of engine tuning inspection corresponding to the safe operation and environment of a driving gasoline car. The effects of tuning on the characteristics of performance and exhaust emissions under a wide range of engine speeds are experimentally investigated by the actual driving car with a four-cycle, four-cylinder DOHC, turbo-intercooler, water-cooled gasoline engine operating at four types of non-tuning, tuning 1, 2 and 3. The tuning parts in the gasoline engine are the intake manifold, intake pipe and air filter. In the experiment, the output, torque and air-fuel ratio of the five-speed automatic transmission vehicles were measured at the chassis dynamometer(Dynojet 224xLC) with one person on board. The exhaust emissions of $NO_X$, THC, CO, $O_2$ and $CO_2$, and excess air ratio(${\lambda}$) at the other chassis dynamometer(DASAN-MD-ASM-97-KR-HD) were also measured by the idle/constant-speed mode(ASM2525 mode) test method. It is found that the actual air-fuel ratios of non-tuning and tuning engines were shown to be lower than the stoichiometric air-fuel ratio with increasing engine speed, and the actual air-fuel ratio of non-tuning engine was slightly higher than those of tuning engines when the engine speed is more than 4000 rpm. The output was significantly increased by the tuning whereby the maximum output of tuning engine was more increased to approximately 117.64% than that of non-tuning engine. In addition, CO, THC and $NO_X$ emissions of non-tuning and tuning engines measured by the constant-speed test mode were all satisfied with the inspection standards. CO emission was increased, while THC and $NO_X$ emissions were reduced by tuning.

• Journal of Biomedical Engineering Research
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• v.32 no.2
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• pp.177-184
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• 2011

In this study, the system for application of the bone stimulation was implemented using high frequency and low strain method. The whole system consists of the high frequency and low strain vibration stimulation system 177 for stimulating bone, LVDT sensor, and wireless sensor based on tri-axial accelerometer. To evaluate the usefulness of the system, the frequencies and accelerations from function generator were applied to the vibration stimulation system. The range of frequency was 17 Hz, 30 Hz, 45 Hz, 50 Hz and the range of acceleration was set 0.3 g, 0.6 g, 1g, and 2 g. The measured frequencies and acceleration using LVDT (linear variable difference transformer) sensor and 3-axial accelerometer were estimated and compared. The range of frequencies average difference was from 0.0 to 0.004 Hz. As the standard deviation of frequencies estimated by LVDT sensor and accelerometer was below 0.03 Hz and the output frequencies of function generator were similar: Also the results of t-test were satisfied with conditions of p > 0.05. And the acquired frequencies and acceleration from vibration measuring device module were estimated and analyzed. As the mean of accelerations was similar to the acceleration applied from function generator. And the standard deviation of acceleration estimated from vibration measuring device module was ranged from 0.019 g to 0.038 g. Also the results of t-test were satisfied with conditions of p > 0.05. Therefore, these results were airy similar to the acceleration applied from function generator. As a result, the usefulness of the system was confirmed. n a further study, clinical experiment will be carried out with the authorization of IRB (institutional review board) so that appropriate frequency and strain would be investigated in clinical field.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6C
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• pp.339-347
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• 2008

The penetration of the probe produces the excess pore pressure due to the disturbance. The objective of this study is to evaluate the disturbance zone by using the dissipation of the excess pore water pressure, which was generated due to the penetration of the penetrometer with different size. The CPT, DMT and FVP (Field Velocity Probe) are adopted for in-situ tests. The tests are carried out in the construction site of north container pier of Busan new port, Korea where is accelerating the consolidation settlement using plastic board drains (PBD) and surcharges by crushed gravels. The coefficient of consolidation $(C_h)$ and soil properties are deduced by the laboratory test. The in-site tests are performed after the predrilling the surcharge zone at the point of 90% degree of consolidation. To minimize the penetration effect, the horizontal distance between penetration tests is 3m, the change of the pore pressure is monitored at the fixed depth of 24m. The coefficient of consolidation $(C_h)$ and the $t_{50}s$ are calculated based on the laboratory test and the in-situ data, respectively. The equvalent radi based on the $t_{50}$ shows that the FVP and the DMT produce the smallest and the greatest equivalent radi, respectively.

• Imaging Science in Dentistry
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• v.54 no.3
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• pp.271-275
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• 2024

Purpose: Recent advancements in artificial intelligence (AI), particularly tools such as ChatGPT developed by OpenAI, a U.S.-based AI research organization, have transformed the healthcare and education sectors. This study investigated the effectiveness of ChatGPT in answering dentistry exam questions, demonstrating its potential to enhance professional practice and patient care. Materials and Methods: This study assessed the performance of ChatGPT 3.5 and 4 on U.S. dental exams - specifically, the Integrated National Board Dental Examination (INBDE), Dental Admission Test (DAT), and Advanced Dental Admission Test (ADAT) - excluding image-based questions. Using customized prompts, ChatGPT's answers were evaluated against official answer sheets. Results: ChatGPT 3.5 and 4 were tested with 253 questions from the INBDE, ADAT, and DAT exams. For the INBDE, both versions achieved 80% accuracy in knowledge-based questions and 66-69% in case history questions. In ADAT, they scored 66-83% in knowledge-based and 76% in case history questions. ChatGPT 4 excelled on the DAT, with 94% accuracy in knowledge-based questions, 57% in mathematical analysis items, and 100% in comprehension questions, surpassing ChatGPT 3.5's rates of 83%, 31%, and 82%, respectively. The difference was significant for knowledge-based questions(P=0.009). Both versions showed similar patterns in incorrect responses. Conclusion: Both ChatGPT 3.5 and 4 effectively handled knowledge-based, case history, and comprehension questions, with ChatGPT 4 being more reliable and surpassing the performance of 3.5. ChatGPT 4's perfect score in comprehension questions underscores its trainability in specific subjects. However, both versions exhibited weaker performance in mathematical analysis, suggesting this as an area for improvement.

• The Journal of Korean Society for Radiation Therapy
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• v.23 no.1
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• pp.1-6
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• 2011

Purpose: Immobilizations used in order to maintain the reproducibility of a patient set-up and the stable posture for a long period are important more than anything else for the accurate treatment when the stereotactic body radiotherapy is underway. So the purpose of this study is to adapt the optimum immobilizations for the stereotactic body radiotherapy by comparing two commercial immobilizations with the self-manufactured immobilizations. Materials and Methods: Five people were selected for the experiment and three different immobilizations (A: Wing-board, B: BodyFix system, C: Arm up holder with vac-lock) were used to each target. After deciding on the target's most stable respiratory cycles, the targets were asked to wear a goggle monitor and maintain their respiration regularly for thirty minutes to obtain the respiratory signals. To analyze the respiratory signal, the standard deviation and the variation value of the peak value and the valley value of the respiratory signal were separated by time zone with the self-developed program at the hospital and each tie-downs were compared for the estimation by calculating a comparative index using the above. Results: The stability of each immobilizations were measured in consideration of deviation changes studied in each respiratory time lapse. Comparative indexes of each immobilizations of each experimenter are shown to be A: 11.20, B: 4.87, C: 1.63 / A: 3.94, B: 0.67, C: 0.13 / A: 2.41, B: 0.29, C: 0.04 / A: 0.16, B: 0.19, C: 0.007 / A: 35.70, B: 2.37, C: 1.86. And when all five experimenters wore the immobilizations C, the test proved the most stable value while four people wearing A and one man wearing D expressed relatively the most unstable respiratory outcomes. Conclusion: The self-developed immobilizations, so called the arm up holder vac-lock for the stereotactic body radiotherapy is expected to improve the effect of the treatment by decreasing the intra-fraction organ motions because it keeps the respiration more stable than other two immobilizations. Particularly in case of the stereotactic body therapy which requires the maintenance of set-up state for a long time, the self-developed immobilizations is thought to more useful for stereotactic body radiotherapy rather than the rest two immobilizations with instable respiratory cycle as time passes.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.1 s.6
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• pp.15-29
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• 2005

Truck Shipment Safety Information, which is a part of the development of NERIS is divided into Optimal Route Guidance System and Emergency Response System. This research is for establishing an advance warning system, which aims for preventing damages(fire, explosion, gas-escape etc.) and detecting incidents that are able to happen during transporting hazardous materials in advance through monitoring the position of moving vehicles and the state of hazardous materials in real-time. This research is peformed to confirm the practical possibility of application of the advance warning system that monitors whether the hazardous materials transport vehicles move the allowed routes, finds the time and the location of incidents of the vehicles promptly and develops the emergency system that is able to respond to the incidents as well by using the technologies of CPS, CDMA and CIS with testing the ability of performance. As the results of the test, communication accuracies are 99$\%$ in freeway, 96$\%$ in arterial, 97$\%$ in hilly sections, 99$\%$ in normal sections, 96$\%$ in local sections, 99$\%$ in urban sections and 98$\%$ in tunnels. According to those results, the system has been recorded a high success rate of communication that enough to apply to the real site. However, the weak point appeared through the testing is that the system has a limitation of communication that is caused in the rural areas and certain areas where are fewer antennas that make communication possible between on-board unit and management server. Consequently, for the practical use of this system, it is essential to develop the exclusive en-board unit for the vehicles and find the method that supplements the receiving limitation of the GPS coordinates inside tunnels. Additionally, this system can be used to regulate illegal acts automatically such as illegal negligence of hazardous materials. And the system can be applied to the study about an application scheme as a guideline for transporting hazardous materials because there is no certain management system and act of toxic substances in Korea.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.10
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• pp.441-450
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• 2014

The stock market is constantly changing and sometimes the stock prices unaccountably plummet or surge. So, the stock market is recognized as a complex system and the change on the stock prices is unpredictable. Recently, many researchers try to understand the stock market as the network among individual stocks and to find a clue about the change of the stock prices from big data being created in real time from Internet. We focus on the correlation between the stock prices and the human interactions in Internet especially in the stock message boards. To uncover this correlation, we collected and investigated the articles concerning with 57 target companies, members of KOSPI200. From the analysis result, we found that there is no significant correlation between the stock prices and the article volume, but the strength of correlation between the article volume and the stock prices is relevant to the stock return. We propose a new method for recommending stock portfolio base on the result of our analysis. According to the simulated investment test using the article data from the stock message boards in 'Daum' portal site, the returns of our portfolio is about 1.55% per month, which is about 0.72% and 1.21% higher than that of the Markowitz's efficient portfolio and that of the KOSPI average respectively. Also, the case using the data from 'Naver' portal site, the stock returns of our proposed portfolio is about 0.90%, which is 0.35%, 0.40%, and 0.58% higher than those of our previous portfolio, Markowitz's efficient portfolio, and KOSPI average respectively. This study presents that collective human behavior on Internet stock message board can be much helpful to understand the stock market and the correlation between the stock price and the collective human behavior can be used to invest in stocks.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.4
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• pp.302-307
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• 2001

The underwater background noise measured in Geoje and Tongyoung diving fishing ground from May to December, 2000 and analyzed to get optimum carrier frequency and transmitter power level for underwater wireless telephone design. The results obtained are summarized as follows: 1. At the Geoje and Tongyoung diving fishing ground, the lowest ambient noise band was 25~30kHz with 57dB and 52dB re 1$\mu$Pa, respectively. 2. At the Geoje and Tongyoung diving fishing ground, the lowest noise band during fishing activity was 67dB and 62dB re 1$\mu$Pa, respectively. 3. At the Geoje diving fishing ground, the noise of water jetter which is a digging machine for subbottom shells was 102dB re 1$\mu$Pa. 4. Considering the design parameters of underwater wireless telephone, it is found that the optimum carrier frequency band is around 30kHz and the transmitter source level should be at least 131dB re 1$\mu$Pa for 500m range telephone.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.6 no.2
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• pp.10-18
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• 1988

In the three-dimensional analysis and deformation analysis of large structures, efficient is the use of the multiple method of close range photogrammetry which approaches the object distance. This study analyzes the influence of errors according to the overlap, the control points, and the object distance, to solve the problems which are raised in the multiple method. A wall-board, 7 meters by 3 meters, was used as a test field on which a total of 225 unknown points were equally disposed. The photographs with changing the overlap and object distance were taken by P-31 camera system. a total of 143 negatives are used in this study for computing 3-dimensional coordinates and its standard errors, and bundle adjustment of strips and blocks developed with on-line system is applied. In case of decreasing the number of control points, simulation error increases but actual error decreases and increases again. Due to the changed of object distances Z error represents largely compared to X, Y error, but good results in Z can be obtained by increasing the redundancy. And simulation error or actual error shows best results at the endlap of about 70%. To sum up this study, approprate arrangement of control points and overlap is meaningful, and multiple method by short object distance will be widely used to precision and deformation analysis of critical structures.