• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.5B
• /
• pp.475-488
• /
• 2003

To prevent performance degradation of TCP due to packet losses in the smooth handoff by the route optimization extension of Mobile IP protocol, a buffering of packets at a base station is needed. A buffering of packets at a base station recovers those packets dropped during handoff by forwarding buffered packets at the old base station to the mobile user. But, when the mobile user moves to a congested base station in a new foreign subnetwork, those buffered packets forwarded by the old base station are dropped and TCP transmission performance of a mobile user in the congested base station degrades due to increased congestion by those forwarded burst packets. In this paper, considering the general case that a mobile user moves to a congested base station, we analyze the influence of packet buffering on TCP performance according to handoff arrival distribution for Drop-tail and RED (Random Early Detection) buffer management schemes. Simulation results show that RED scheme can reduce the congestion increased by those forwarded burst packets comparing Drop-Tail, but RED scheme cannot avoid Global Synchronization due to forwarded burst packets by the old base station and new buffer management scheme to avoid it is needed in Mobile IP based networks.

• Journal of Navigation and Port Research
• /
• v.43 no.1
• /
• pp.23-32
• /
• 2019

In this paper, we proposed a multi-chain Time of Arrival (ToA) positioning method to estimate positions using all received Loran-C signals from multiple chains without constraining to a single chain. Conventionally, we have to choose only one chain among several available chains for position estimation using Loran-C. Therefore, the number of signals to be used for positioning is limited to three to five. In general, if more signals are used for positioning estimation, its performance tends to be improved in terms of accuracy and availability. To validate the proposed method for multi-chain Loran-C, we firstly carried out a static positioning test in land. By analyzing the test results, we confirmed that the proposed method works well under a multi-chain Loran-C scenario. Subsequently, another mobile positioning test was conducted on board a vessel under a practical application scenario. From this second test, we successfully demonstrated that the multi-chain ToA positioning method even in situations where the conventional single-chain Loran-C approach fails for positioning.

• Journal of The Korean Society of Clinical Toxicology
• /
• v.16 no.2
• /
• pp.75-85
• /
• 2018

Purpose: This study examined the Poisoning Severity Score (PSS) from acute poisoning patients, to determine the relationships among the PSS, PSSsum, the primary outcome (prolonged stay at the ER over 24 hours, general ward and ICU admission and the application of intubation and mechanical ventilator, and the administration of inotropes). Methods: A retrospective study was conducted through the EMR for 15 months. The PSS grade was classified according to the evidence of symptoms and signs. The differences in the primary outcomes between the PSS of when a single organ was damaged, and the PSS, PSSsum combined with the grade of when multiple organs were damaged, were studied. The cutoff value was calculated using the receiving operating characteristics (ROC) curve. Results: Of the 284 patients; 85 (29.9%) were men with a mean age of 48.8 years, and their average arrival time to the ER was $4.4{\pm}6.7\;hours$. The most frequently used drug was hypnotics. The number of patients with PSS grade 0, 1, 2, 3, and 4 was 17, 129, 122, 24, and one, respectively. No ICU admissions, application of intubation and mechanical ventilators, administration of inotropes were observed among the patients with PSS grades 0 and 1 but only on patients with PSS grades 2 to 4. At PSS, when separating the patients according to the number of damaged organs, 17 had no symptoms, 133 had one organ damaged, 75 had two organs damaged, 36 had three organs damaged, and 23 had four organs damaged. Significant differences were observed between increasing number of damaged organs and the primary outcome. Conclusion: Among the acute poisoning patients, the PSS was higher in severity when the grade was higher. The number of damaged organs and the primary outcome showed meaningful statistical differences. This study confirmed that when the patients' PSS>2 and PSSsum>5, the frequency of ICU admission was higher, and they were considered to be severe with an increased prescription risk of application of intubation and mechanical ventilator, and the administration of inotropes.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.15 no.1
• /
• pp.45-55
• /
• 2022

Currently, the Collective Control Algorithm is the most popular elevator algorithm. The Collective Control Algorithm allows the user to use the elevator when the direction of movement of the elevator and the direction of the user's destination are the same. However, the algorithm has a problem in that only one elevator responds to a user's call when the user's waiting time and using multiple elevators. To solve this problem, this paper proposes a new hybrid HRN algorithm based on the highest response ratio next (HRN) algorithm. In general, HRN Algorithm requires a user's boarding time and getting off time, but due to the nature of the elevator, it is difficult to predict the user's call in advance. Therefore, to overcome these limitations, this paper proposes Hybrid HRN Algorithm that considers the distance between the user's call location and the arrival location. This paper shows that Hybrid HRN Algorithm, proposed through experiments, has an average waiting time of 23.34 seconds, a standard deviation of 11.86, a total moving distance of 535.2m, a total operating time of 84sec, and a driving balance between the two elevators is 92m, which is superior to the previously suggested Collective Control, Zoning, and 3-Passage Algorithm.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.23 no.1
• /
• pp.61-81
• /
• 2024

eCall system assists traffic accident victims by connecting emergency rescue institutions with accurate accident information, helping them to identify the on-site situation in the event of a traffic accident. The purpose of this paper is to develop a Korean eCall system that reflects the requirements of domestic emergency rescue institutions and to analyze the expected effects through an integrated demonstration. The results of an integrated demonstration indicated that the communication success rate between the eCall IVS and the call center was 99.25%, and the average location information error was 1.2 m. In particular, it has been confirmed that the average location information error is less than 21.6 meters, as assessed by the Korea Communications Commission when evaluating the accuracy of domestic emergency rescue location information. When the eCall system was introduced, it was confirmed that the time from traffic accidents to hospital arrival could be shortened by 3 m 38 s for highways and 1 m 22 s for general roads. By it to traffic deaths from 2005 to 2022, it was analyzed that the number of fatalities decreased by 82,662, resulting in a reduction of approximately social costs.

• Journal of Navigation and Port Research
• /
• v.47 no.6
• /
• pp.341-349
• /
• 2023

Gamcheon Port, which is one of three major harbors in the Port of Busan, is being operated to load, discharge and transport a wide range of cargoes, including general cargo, fisheries, steel products, cement, etc,. The harbor, designated as a compulsory pilotage area, provides pilotage services in compliance with relevant laws and regulations for arrival and departure of vessels in the Gamcheon Port area. Some academic research on the marine traffic environment in Gamcheon Port has been conducted. However, the pilotage environment and hazards to pilotage safety in the port have yet to be studied. Therefore, in this research, the pilotage environment and hazards to pilotage safety were identified, and it was confirmed that there are hazards to pilotage safety, such as vessels installed poor facilities including damaged pilot boarding arrangements, vessels blocking pilot's view by her structures and fishing nets, vessels unable to communicate in English, vessels not following VTS's order. The hazards to pilotage safety were also stratified, and the importance of the hazards was verified in accordance with a survey based on Analytic Hierachy P rocess(AHP) for Busan Harbor pilots, and safety measures to secure pilotage safety were examined to secure the safety of vessels calling Gamcheon Port.

• The Korean Journal of Air & Space Law and Policy
• /
• v.30 no.2
• /
• pp.249-277
• /
• 2015

Regulation (EC) No 261/2004 ("Regulation") is a common rule on compensation and assistance to passengers in the event of denied boarding and of cancellation or long delay of flights. In some recent cases of European nations, passengers sued the air carrier in order to obtain monetary compensation under Article 7(1) of the Regulation. Some courts dismissed the actions on the grounds that, unlike denied boarding or cancellation of the flight, the Regulation provides no compensation in relation to delayed flights. However, Court of Justice of the European Union(CJEU) ruled that Regulation 261/2004 must be interpreted to mean that passengers whose flights are delayed have a right to compensation in cases when the loss of time is equivalent to, or is in excess of three hours - where the passengers eventually reached their final destination three hours or more later than the originally scheduled arrival time. It is true that a strict interpretation of the regulation would suggest that passengers whose flight has merely been delayed are not entitled to compensation. They should only be offered assistance in accordance with the Articles 6 and 9. Nevertheless, the Court recognized the same right to the same compensation for passengers of flights delayed by more than three hours as that explicitly provided for passengers of cancelled flights. On the one hand, the Court bases this ruling on the recitals of the Regulation, in which the legislature links the question of compensation to that of a long delay, while indicating that the Regulations seek to ensure a high level of protection for passengers regardless of whether they are denied boarding or their flight is cancelled or delayed. On the other hand, the Court interprets the relevant provisions of the Regulation in light of the general principle of equal treatment. Furthermore, the Court delivered a ruling that the loss of time inherent in a flight delay, which constitutes an inconvenience within the intention of Regulation No 261/2004 and which cannot be categorized as 'damage occasioned by delay' within the meaning of Article 19 of the Montreal Convention, cannot come within the scope of Article 29 of that convention. Consequently, under this view, the obligation under Regulation No 261/2004 intended to compensate passengers whose flights are subject to a long delay is in line with Article 29 of the Montreal Convention. Although the above interpretation of the Court can be a analogical interpretation, the progressive attitude of the Regulation and the view of Court forward to protect passengers' interest is a leading role in the area of international air passenger transportation. Hopefully, after the model of the positive support in Europe, Korea can establish a concrete rule for protecting passengers' right and interest.

• Journal of Intelligence and Information Systems
• /
• v.22 no.4
• /
• pp.247-264
• /
• 2016

With the rapid acceleration of low-birth rate and population aging, the employment of the neglected groups of people including the middle aged class is a crucial issue in South Korea. In particular, in the 2010s, the number of the middle aged who want to find a new job after retirement age is significantly increasing with the arrival of the retirement time of the baby boom generation (born 1955-1963). Despite the importance of matching jobs to this emerging middle aged class, private job portals as well as the Korean government do not provide any online job service tailored for them. A gigantic amount of job information is available online; however, the current recruiting systems do not meet the demand of the middle aged class as their primary targets are young workers. We are in dire need of a specially designed recruiting system for the middle aged. Meanwhile, when users are searching the desired occupations on the Worknet website, provided by the Korean Ministry of Employment and Labor, users are experiencing discomfort to search for similar jobs because Worknet is providing filtered search results on the basis of exact matches of a preferred job code. Besides, according to our Worknet data analysis, only about 24% of job seekers had landed on a job position consistent with their initial preferred job code while the rest had landed on a position different from their initial preference. To improve the situation, particularly for the middle aged class, we investigate a soft job matching technique by performing the following: 1) we review a user behavior logs of Worknet, which is a public job recruiting system set up by the Korean government and point out key system design implications for the middle aged. Specifically, we analyze the job postings that include preferential tags for the middle aged in order to disclose what types of jobs are in favor of the middle aged; 2) we develope a new occupation classification scheme for the middle aged, Korea Occupation Classification for the Middle-aged (KOCM), based on the similarity between jobs by reorganizing and modifying a general occupation classification scheme. When viewed from the perspective of job placement, an occupation classification scheme is a way to connect the enterprises and job seekers and a basic mechanism for job placement. The key features of KOCM include establishing the Simple Labor category, which is the most requested category by enterprises; and 3) we design MOMA (Middle-aged Occupation Matching Algorithm), which is a hybrid job matching algorithm comprising constraint-based reasoning and case-based reasoning. MOMA incorporates KOCM to expand query to search similar jobs in the database. MOMA utilizes cosine similarity between user requirement and job posting to rank a set of postings in terms of preferred job code, salary, distance, and job type. The developed system using MOMA demonstrates about 20 times of improvement over the hard matching performance. In implementing the algorithm for a web-based application of recruiting system for the middle aged, we also considered the usability issue of making the system easier to use, which is especially important for this particular class of users. That is, we wanted to improve the usability of the system during the job search process for the middle aged users by asking to enter only a few simple and core pieces of information such as preferred job (job code), salary, and (allowable) distance to the working place, enabling the middle aged to find a job suitable to their needs efficiently. The Web site implemented with MOMA should be able to contribute to improving job search of the middle aged class. We also expect the overall approach to be applicable to other groups of people for the improvement of job matching results.

• Korean Journal of Heritage: History & Science
• /
• v.53 no.4
• /
• pp.216-233
• /
• 2020

This study set out to review tomb culture in the Gyeongju region during the Bronze Age, and also examine the patterns of dolmens during their end phase. For these purposes, the study analyzed 18 tomb relics from the Bronze Age and nine from the early Iron Age. Gyeongju belongs to the Geomdan-ri cultural zone. Approximately 120 tombs from the Bronze Age have been excavated in the Gyeongju region. There are fewer tombs than dwellings in the region, which is a general characteristic of the Geomdan-ri cultural zone. Although the number of tombs is small, the detailed structure of the dead body is varied. During the Bronze Age, tombs in the Gyeongju region were characterized by more prolific construction of pit tombs, dolmens with boundaries, and stacked stone altars than were the cases in other areas. There is a great possibility that the pit tombs in the Gyeongju region were influenced by their counterparts in the northeastern parts of North Korea, given the spindle whorl artifacts buried at the Dongsan-ri sites. Dolmens with boundaries and stacked stone altars are usually distributed in the Songguk-ri cultural zone, and it is peculiar that instances of these are found in large numbers in the Gyeongju region as part of the Geomdanri cultural zone. Even in the early Iron Age, the building of dolmens with boundaries and stacked stone altars continued in the Gyeongju region under the influence of the Bronze Age. A new group of people moved into the area, and they crafted ring-rimmed pottery and built wooden coffin tombs. In the early Iron Age, new rituals performed in high places also appeared, and were likely to provide venues for memorial services for heavenly gods in town-center areas. The Hwacheon-ri Mt. 251-1 relic and the Jukdong-ri relic are ruins that exhibit the aspect of rituals performed in high places well. In these rituals performed in high places, a stacked stone altar was built with the same form as the dolmens with boundaries, and a similar rock to the cover stone of a dolmen was used. People continued to build and use dolmens with boundaries and stacked stone altars while sustaining the Bronze Age traditions, even into the early Iron Age, because the authority of dolmens was maintained. Some dolmens with boundaries and stacked stone altars, known as being Bronze Age in origin, would have continued to be used in ritual practices until the early Iron Age. Entering the latter half of the second century B.C., wooden coffin tombs began to propagate. This was the time when the southern provinces, including the Gyeongju region, were included in the East Asian network, with the spread of ironware culture and the arrival of artifacts from central China. Around this time, dolmen culture faded into history with a new era beginning in its place.