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A Template-based Interactive University Timetabling Support System (템플릿 기반의 상호대화형 전공강의시간표 작성지원시스템)

  • Chang, Yong-Sik;Jeong, Ye-Won
    • Journal of Intelligence and Information Systems
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    • v.16 no.3
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    • pp.121-145
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    • 2010
  • University timetabling depending on the educational environments of universities is an NP-hard problem that the amount of computation required to find solutions increases exponentially with the problem size. For many years, there have been lots of studies on university timetabling from the necessity of automatic timetable generation for students' convenience and effective lesson, and for the effective allocation of subjects, lecturers, and classrooms. Timetables are classified into a course timetable and an examination timetable. This study focuses on the former. In general, a course timetable for liberal arts is scheduled by the office of academic affairs and a course timetable for major subjects is scheduled by each department of a university. We found several problems from the analysis of current course timetabling in departments. First, it is time-consuming and inefficient for each department to do the routine and repetitive timetabling work manually. Second, many classes are concentrated into several time slots in a timetable. This tendency decreases the effectiveness of students' classes. Third, several major subjects might overlap some required subjects in liberal arts at the same time slots in the timetable. In this case, it is required that students should choose only one from the overlapped subjects. Fourth, many subjects are lectured by same lecturers every year and most of lecturers prefer the same time slots for the subjects compared with last year. This means that it will be helpful if departments reuse the previous timetables. To solve such problems and support the effective course timetabling in each department, this study proposes a university timetabling support system based on two phases. In the first phase, each department generates a timetable template from the most similar timetable case, which is based on case-based reasoning. In the second phase, the department schedules a timetable with the help of interactive user interface under the timetabling criteria, which is based on rule-based approach. This study provides the illustrations of Hanshin University. We classified timetabling criteria into intrinsic and extrinsic criteria. In intrinsic criteria, there are three criteria related to lecturer, class, and classroom which are all hard constraints. In extrinsic criteria, there are four criteria related to 'the numbers of lesson hours' by the lecturer, 'prohibition of lecture allocation to specific day-hours' for committee members, 'the number of subjects in the same day-hour,' and 'the use of common classrooms.' In 'the numbers of lesson hours' by the lecturer, there are three kinds of criteria : 'minimum number of lesson hours per week,' 'maximum number of lesson hours per week,' 'maximum number of lesson hours per day.' Extrinsic criteria are also all hard constraints except for 'minimum number of lesson hours per week' considered as a soft constraint. In addition, we proposed two indices for measuring similarities between subjects of current semester and subjects of the previous timetables, and for evaluating distribution degrees of a scheduled timetable. Similarity is measured by comparison of two attributes-subject name and its lecturer-between current semester and a previous semester. The index of distribution degree, based on information entropy, indicates a distribution of subjects in the timetable. To show this study's viability, we implemented a prototype system and performed experiments with the real data of Hanshin University. Average similarity from the most similar cases of all departments was estimated as 41.72%. It means that a timetable template generated from the most similar case will be helpful. Through sensitivity analysis, the result shows that distribution degree will increase if we set 'the number of subjects in the same day-hour' to more than 90%.

Microbiological Evaluation of Raw Vegetables (비가열 섭취 채소류의 미생물 오염도 조사)

  • Jung, Seung-Hye;Hur, Myung-Je;Ju, Jeong-Hwa;Kim, Kyung-Ae;Oh, Sung-Suck;Go, Jong-Myoung;Kim, Yong-Hee;Im, Jeong-Soo
    • Journal of Food Hygiene and Safety
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    • v.21 no.4
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    • pp.250-257
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    • 2006
  • The purpose of this study is to evaluate microbiological contamination of leafy vegetables. Total aerobic bacteria and coliforms were monitored to get the contamination levels and Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, Escherichia coli, Escherichia coli O157:H7, Salmonella spp., Vibrio parahaemolyticus, Listeria monocytogenes, Yersinia enterocolitica, Campylobacter jejuni to detect pathogens with risk of foodpoisoning from fresh vegetables. The colony count of total aerobes and coliforms was also performed to determine the efficacy of washing with tab water by common consumers. 124 samples which are divided into 8 kinds of vegetables - Sesame leaf, Dropwort, Chinese cabbage, Korean leek, Lettuce, Crown daisy, Pimpinella brachycarpa, Chicory were sampled in 2 wholesale markets in Incheon. Mean counts of total aerobic bacteria for individual vegetables ranged from $2.2\times10^6\;CFU/g\;to\;6.0\times10^7\;CFU/g$ and total coliforms were from $4.1\times10^5\;CFU/g\;to\;9.8\times10^6\;CFU/g$. Both show the peaks in summer on this study from March to September. Decrease rates after washing with tab water averaged 81.0% and 82.5% in total aerobic bacteria and coliform counts respectively. Staphylococcus aureus was isolated 8.1%, Bacillus cereus 14.5%, Clostridium perfringens 5.6%, Escherichia coli 18.5%. 11 samples showed overlapped bacterial contamination. For respective vegetables Staphylococcus aureus isolated from 0.0% to 22.2%, Bacillus cereus from 0.0% to 29.4%, Clostridium perfringens from 0.0% to 23.1 %, Escherichia. coli from 0.0% to 35.0%. Escherichia coli O157:H7, Salmonella spp., Vibrio parahaemolyticus, Listeria monocytogenes, Yersinia enterocolitica, Campylobacter jejuni were not isolated. This study is expected to be available as the reference for the basal data of pathogens in fresh vegetables.

PASKYULA's Theory of Art (파스큐라의 미술론)

  • Jung, Ju-Young
    • The Journal of Art Theory & Practice
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    • no.5
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    • pp.43-80
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    • 2007
  • PASKYULA was formed in September, 1923 through the union of artists involved in two art groups: Kim Ki-Jin, Kim Bok-Jin, Yeon Hak-Nyeon who had previously participated in the ToWolHoi, and Park Young-Hi, Lee Sang-Hwa, An Seok-Ju, former members of the BaeckJo. After its founding, the PASKYULA artists had been searching for the social function of art to reform the harsh reality of Minjung and the nation with criticism toward society as well as art world. Their art theory for MinJung could grow relatively ease in relation to changing social and political conditions in the early 1920s. In August, 1925, PASKYULA organized the Korea Artista Proletaria Federatio with the YeomGunSa, and laid the groundwork for Proletariat art movement which was regularized in the late 1920s. From PASKYULA up to the early state of KAPF, the theory of art advocated by Kim Bok-Jin and An Seok-Ju could be summarized as "art for MinJung". At that time, widely ranging discourses on MinJung, however, was spawned in art theory, because many intellectuals-including artists and writers-begun to pay more attention to MinJung, who emerged as one of the social forces after the Samil Independent Movement. Sometimes, MinJung was construed as the target of enlightenment from a negative viewpoint. On the other hand, several intellectuals under the influence of individualism asserted that the discussion itself on MinJung exerted an evil influence on art. In contrast of these cases, the PASKYULA artists including Kim Bok-Jin, An Seok-Ju perceived that MinJung had the potential to change society, and regarded them as "a creator of genuine civilization and art". In the PASKYULA artist's writings, the concept of MinJung was often overlapped with the meaning of the Choson nation suffering under colony. Although their concept of MinJung was transformed gradually into the proletariat as they were under the strong influence of socialism, it did not change that they grasped the realities of the whole Choson Peninsula through the proletarian consciousness. In the early state of PASKYULA, the methodology for social function of art was presented in a twofold manner. First of all, Kim Bok-Jin emphasized on the necessity of education to improve MinJung's way of life through art, and it was embodied by the organization of ToWol Art Workshop and public lecture. Also, he championed "the popularization of art", which was one of methods to distribute art to MinJung. According to the PASKYULA artists, art should be not art for art' sake but art for MinJung. That was why they advocated the convergence of art and MinJung's life. Especially Kim Bok-Jin affirmed a link between art and industry because he considered industry the field inextricably linked with MinJung's life. In this context, his idea could be read as the generalization and equalization within the framework of possession. Kim Bok-Jin thought that the social ramifications of capitalism deprived MinJung of their right to enjoy art, and emphasized the artist' social role to return the right to them. That is, the even distribution of art was mainly discussed than the contents of art in the half of 1920s. By 1925, the contents of art itself became an issue in the PASKYULA art theory, and it was based in realism. Kim Bok-Jin and An Seok-Ju insisted that art should be reflection of real life. At that time, realism acquired the representation of MinJung and the nation's realities not realistic style. In fact, the various Western art styles including Futurism, Constructivism, Cubism etc. were exploited in the PASKYULA's visual images. Western art, target of criticism on theory, was selectively adopted in the works which were produced by Kim Bok-Jin and An Seok-Ju. Kim Bok-Jin's MoonYeUnDong cover design was conceived of as the example in which Western art was adopted with it's ideology under the influence of MAVO, while Western art shown in An Seok-Ju's illustrations served as a decorative function in many cases. Especially, An Seok-Ju attempted the various styles of Western art simultaneously, which may be seen as representing that PASKYULA did not have a firm ideology for their style. Also, it can be read as showing his hasty zeal to overcome Western art rapidly. The wish to establish "art for MinJung" as soon as possible was accompanied with the will to jump over the all steps of Western art though it was superficial. This aspiration of PASKYULA was expressed through the mass media, which had the potential for communicating to MinJung. At this point, there was a significant disparity between PASKYULA and another art groups in the first half of 1920s. However, the PASKYULA's method on the basis of the mass media could not but have a certain limitation because of the medium's properties. Nevertheless, PASKYULA' attempts may be considered to be valuable in sense that they expended the boundaries of Korean modern art into the commercial art questioning the matter of the distribution for art.

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A Study on Improvement of Vital Registration and Statistics System in Korea (인구동태신고 및 통계조사의 개선방안)

  • 신윤재
    • Korea journal of population studies
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    • v.11 no.1
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    • pp.58-75
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    • 1988
  • 1.Objectives of the Study It is a well known fact that a prompt and reliable data on demographic information is essential in a proper planning and evaluation of any program of national or community level. Especially vital statistics are an important demographic component among demographic information. Realizing the importance of vital statistics, the government has made some efforts for years to improve the vital registration system which has a close relationship with the production of vital statistics. However, it is still observed that there are some limitations in utilizing vital registration data due to considerable amount of vital events which are never registered and registered but not in time or inaccurately, even though vital registration system in Korea has sound legal basis. In this connection, the objectives of the study is as follows :(1) To examine some problems of the vital registration system in various aspects, (2) To make improvement programme of continuous Demographic Survey as a supplementary source of vital statistics, and (3) To find out some alternatives for making it possible to produce and utilize the reliable vital statistics by developing analytical methodologies on that. 2. Current Situation of Vital Registration System All the vital events, i.e. births, deaths, marriages and divorces, are to be registered in time under the Civil Registration Law, Statistics Law and Regulation on Vital Statstics as a duty of people. Some recent tendencies in each of recent registration are summarized as below: (1) The completeness of vital registration .Out of all births which are occurred during a year, around 75% of those compared to the estimates are registered in the year of occurrence. .In case of death registration, the percentage of registration in the year of occurrene has been gradually increased from 86.2% in the year of 1980, but it is still below the level of 90% compared to the estimates. .The percentage of registration for marriages and divorces in the year of occurrence out of total registered numbers was revealed to be 69% and 73% respectively in 1985. (2) Continuous Demographic Survey .It is a kind of sample survey for the purpose of producing reliable vital statistics which could not be provided by the vital registration. .It covers about 17, 000 sample households at national level and important information for vital events are collected in every month by 323 expertized enumerators who are regular staff of the government. .Although the result of the survey seems to be more reliable than of vital registration, the reliability of the data is still bellow the acceptable level if compared with relevant information from other sources such as population census or special surveys. 3. Problems of Vital Registration System There are four major obstacles in improving vital registration system in Korea; (1) In general, policy priority is not given on any programme of improving vital registration system. It is, therefore, very difficult to formulate comprehensive programme through having cooperation from related authorities and sufficient financial assistance. (2) In all the laws related and system itself, there is substantial degree of overlap and irrationality. Registration of each vital event is maintained according to several laws and regulation such as Civil Registration Law, Statistics Law, Resident Registration Law and Regulation on Vital Statistics. However they are mutually overlapped and overall supervision can not be done systematically due to lack of co-operation among the authorities concerned. (3) The administration of vital registration system seems to be working inefficiently, because of most of civil servants who are in charge of vital registration are lacking of conception on vital statistics and also there is a certain extent of regidity in handling the works. Therefore, they are doing their jobs in a passive way. (4) A substantial proportion of vital events occurred is not registered within the legal time limit (i.e. within one month after the occurrence in case of birth and death) or not registered forever. Some of social customs and superstitution seem to be the potential causes especially in case of births and deaths. 4. Recommendations for the Improvement of Vital Statistics (1) Reporting systems such as civil registration, vital statistics and resident registration should be integrated under the single law. Also, administrative supervision, personnel and budget with regard to the registration system should be under the control of a single ministry. (2) It is necessary to simplify the procedures and methods of reporting vital events, i.e., reducing number of sheets of the form, making corrections easily, reducing registration items, etc. (3) Continuous Demographic Survey as a supplementary source of vital registration should be improved and special ad-hoc surveys should be conducted wth regular interval. (4) In-depth analysis should be done using various sources of data on vital statistics. 5. Concluding Remarks From this study, we can notice that temporary campaign and motivation programs are not sufficient to improve the quality of vital statistics. Strong intentions and continuous efforts of the government are needed for the improvement of the vital registration system. Furthermore, most of the data collected through the registration are not properly analyzed and utilized, partly due to the lack of appreciation among high-level governmental officials of the need for vital statistics. It is, therefore, requested that long-term improvement programs of vital statistics be implemented with policy priority and continuous efforts be given to this purpose as a long-term goal of development in Korea.

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A reevaluation of the castles and palaces of Goryeo Gangdo (江都) using GIS (고려 강도(江都)의 성곽과 궁궐 재고찰)

  • KANG, Dongseok
    • Korean Journal of Heritage: History & Science
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    • v.54 no.4
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    • pp.174-191
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    • 2021
  • Gangdo (江都), a reproduction of Gaegyeong, was the capital of Goryeo for 39 years. However, due to the urgent wartime situation of the Mongol invasion and the geographical features of Ganghwa Island, the castle system and palace layout were somewhat different from those of Gaegyeong. Gangdo's castle can be understood as a triple castle system consisting of outer castle, middle castle, and inner castle. First, the outer castle was the first to be completed, and it was built at the forefront to prevent the Mongol army from invading in the first place. It is presumed that the section was between Huamdon and Hwadodon in the outer castle during the Joseon Dynasty. The middle castle can be seen as the present 'Middle Castle', a castle built of earth on the outskirts of the Ganghwa-mountain Castle. Considering the sophistication and robustness of the construction method confirmed in the archaeological research, this castle is thought to have been built under a meticulous plan. In other words, as the capital city, it was completed 'at last' as recorded in the Koryo History, after a long 18-year construction process to protect palaces, government offices, and private houses. The inner castle was a castle with the character of a palace. This corresponds to the Old Castle of Ganghwabu (江華府) during the Joseon Dynasty, and it almost coincided with the scale of the composition of Gaegyeong's palace castle. It was a complex functional space, featuring the integration of the palace and the imperial castle, where the main government offices and ancillary facilities, including the palace, were located. Based on the documentary record that these palaces were similar to Gaegyeong's palace, the palace map was overlapped with that of Gaegyeong. The central axis of the building from Seungpyeongmun (昇平門) to Seongyeongjeon (宣慶殿) coincided with Kim Sangyongsunjeol Monument in Ganghwa- Goryeo Palace. Therefore, it seems that the palace of Gangdo had the same basic structure as that of Gaegyeong. However, the inner palace and annexed buildings must have been arranged in consideration of the topographical conditions of Ganghwa, and this is estimated to be the Gunggol area in Gwancheong-ri.

Situations and Challenges of ODA for Sustainability of Asian Cultural Heritage (아시아 문화유산의 지속가능성을 위한 ODA 현황과 과제)

  • Yu, Jae Eun
    • Korean Journal of Heritage: History & Science
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    • v.49 no.3
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    • pp.270-285
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    • 2016
  • Various opinions and discussions have been actively in progress which are connected with cultural heritage since 'Sustainable Development Goals, SDGs' was announced by UN Sustainable Development Summit 2015 as Post-2015 Development Agenda. Apart from SDGs, conservation of cultural heritage itself stands on the basis of sustainability that originality, characteristic, diversity of cultural heritage should be permanently preserved. From that point of view, it is necessary to understand practical ODA for cultural heritage, far from theoretical approaches and policies. This paper is intended to look into the domestic and overseas situation related to ODA of Asian cultural heritage and the mentioned problems, future plans and challenges. First, the background and concepts about ODA were described and then ODA projects which have been carried out by Japan and China as typical ODA countries for Southeast Asia were introduced. ODA of cultural heritage in Korea has relatively recently started for restoration work for historic sites of Laos and Cambodia and its scale and performance do not come to much yet. Therefore, to develop ODA of cultural heritage, there are suggestions as in the followings. First, it is necessary to have a long-term master plan of ODA projects for sustainability of cultural heritage. Second, based on the view from the long-term perspective, the selection and focus for ODA partner countries should be considered, avoiding short-term projects aiming at a number of countries. Not widespread existing projects by other countries, but the model of Korean ODA for cultural heritage only Korea can conduct should be prepared. The next thing is connection with sustainability, and ultimately the conservation of cultural heritage should result in benefit to the natives by giving an impetus to economy as well as fostering tourism of local areas. To accomplish that connection, educational training and building capacity are suggested as the most suitable alternatives. Cultural heritage of each country reflects its indigenous originality and characteristics, therefore, the restoration work should be conducted by people in each country as the best way. From this point of view, ACPCS held by National Research Institute of Cultural Heritage will take a role of a specialized training program in Korean way. Lastly, establishment of a control tower for ODA in Korea is necessary. JCIC(Japan Consortium for International Cooperation in Cultural Heritage), which was set up in Japan for sharing information, establishment of cooperation system and prevention of overlapped projects will be an example we can take into consideration.

Salvage with Reverse Total Shoulder Arthroplasty after the Failure of Proximal Humeral Tumor Treatment (근위 상완골 종양 치료 실패 후 역 견관절 전치환물을 이용한 구제술)

  • Jeon, Dae-Geun;Cho, Wan Hyeong;Kim, Bum Suk;Park, Hwanseong
    • Journal of the Korean Orthopaedic Association
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    • v.53 no.6
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    • pp.505-512
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    • 2018
  • Purpose: Many reconstruction methods have been attempted after an en-bloc resection of the proximal humerus. In particular, the introduction of reverse shoulder arthroplasty (RSA) has made a breakthrough in the functional recovery of the shoulder. Nevertheless, RSA has limitations when the humeral bone stock loss is significant. In addition, it is unclear if RSA is effective in patients showing failure with non-operative treatment of a proximal humeral tumor. Materials and Methods: A reconstruction was performed using an overlapping allograft-RSA composite for 11 patients with a failed proximal humeral construct. Delayed RSA was performed on 6 patients with failed non-operative treatment. The pre- and postoperative Musculoskeletal Tumor Society (MSTS) score and the complications were addressed. Results: Overlapping allograft-RSA composite afforded a stable construct in 11 failed proximal humeral reconstructions and the patient's chief complaints were resolved. The mean time to the union of overlapped allograft-host junction was 5.5 months. Average preoperative MSTS score of 20.3 point increased to 25.7 point, postoperatively. Four of the six patients who had RSA within 4 years from the index operation showed arm elevation of more than $90^{\circ}$ whereas the remaining 5 patients showed some disability. The complications include one case each of dislocation and aseptic infection, which were resolved by changing the polyethylene liner and scar revision, respectively. None of the 6 patients who underwent delayed RSA after the failure of non-operative treatment showed arm elevation more than $90^{\circ}$. Conclusion: An overlapping allograft-RSA composite is a simple and reliable reconstructive modality in patients with massive bone loss. In patients with metastatic cancer necessitating a surgical resection at presentation, early conversion to RSA is recommended to secure functional recovery.

A Study of Disposition of Archaeological Remains in Wolseong Fortress of Gyeongju : Using Ground Penetration Radar(GPR) (GPR탐사를 통해 본 경주 월성의 유적 분포 현황 연구)

  • Oh, Hyun Dok;Shin, Jong Woo
    • Korean Journal of Heritage: History & Science
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    • v.43 no.3
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    • pp.306-333
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    • 2010
  • Previous studies on Wolseong fortress have focused on capital system of Silla Dynasty and on the recreation of Wolseong fortress due to the excavations in and around Wolseong moat. Since the report on the Geographical Survey of Wolseong fortress was published and GPR survey in Wolseong fortress was executed as a trial test in 2004, the academic interest in the site has now expanded to the inside of the fortress. From such context, the preliminary research on the fortress including geophysical survey had been commenced. GPR survey had been conducted for a year from March, 2007. The principal purpose of the recent 3D GPR survey was to provide visualization of subsurface images of the entire Wolseong fortress area. In order to obtain 3D GPR data, dense profile lines were laid in grid-form. The total area surveyed was $112,535m^2$. Depth slice was applied to analyse each level to examine how the layers of the remains had changed and overlapped over time. In addition, slice overlay analysis methodology was used to gather reflects of each depth on a single map. Isolated surface visualization, which is one of 3D analysis methods, was also employed to gain more in-depth understanding and more accurate interpretations of the remain The GPR survey has confirmed that there are building sites whose archaeological features can be classified into 14 different groups. Three interesting areas with huge public building arrangement have been found in Zone 2 in the far west, Zone 9 in the middle, and Zone 14 in the far east. It is recognized that such areas must had been used for important public functions. This research has displayed that 3D GPR survey can be effective for a vast area of archaeological remains and that slice overlay images can provide clearer image with high contrast for objects and remains buried the site.

Documentation of a Forgotten Journey: A Study on Haenghaeng Ilgi (Diary of a Royal Trip) in the Collection of the National Museum of Korea (사도세자 1761년 평양 밀행의 기록 - 국립중앙박물관 소장 <행행일기(幸行日記)> 연구)

  • Kim, Gyuhun
    • MISULJARYO - National Museum of Korea Art Journal
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    • v.97
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    • pp.69-86
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    • 2020
  • Haenghaeng Ilgi (Diary of a Royal Trip) (koo 7152; hereafter Ilgi) in the collection of the National Museum of Korea provides an account of Crown Prince Sado's incognito royal visit to Pyeongyang in the fourth month of 1761. Ilgi was written by Ham Daeil, a low-ranking military officer in Pyeongyang. Ham was singled out for praise by Crown Prince Sado (1735-1762) and served the prince from the seventh day of the fourth month to the first day of the fifth month. Ilgi documented the deeds of Crown Prince Sado during this period and provides detailed information on his incognito visit to Pyeongyang, which was not officially recorded. Ilgi shows characteristics differentiating it from many other diaries. For example, the quality of the paper, neat handwriting, and well-organized sentences differ from those of common diaries. These distinctions indicate that Ilgi is closer to an official document than a private diary written by an individual. Since Ilgi records Crown Prince Sado's incognito visit to Pyeongyang, is only vaguely known otherwise, its contents need to be examined in terms of whether or not they are fully factual. As the first step in such verification, It is traced that Ham Daeil's family history which turned out to match what is written in Ilgi. Moreover, Ilgi mentions about Prince Crown Sado's writing a piece of calligraphy, and a matching piece of calligraphy written by Sado still survives today. It can be confirmed that the contents of Ilgi are factual in at least these regards. However, although Crown Prince Sado was known to have met people from various social classes during his visit to Pyeongyang, Ilgi focuses only on Crown Prince Sado and Ham Daeil. This suggests the possibility that the surviving version of Ilgi may be an edited condensation based on original texts containing more complete information on Crown Prince Sado's visit. Ilgi is presumed to have been produced during the generation of Ham Jeonghui, a son of Ham Daeil. The dates of birth and death of Ham Daeil fall during the reign of King Yeongjo. It is unlikely that any records regarding Crown Prince Sado would have been published while King Yeongjo, who was hostile to Sado, ruled the country. Ilgi also provides strong evidence that Ham Jeonghui presented the subsequent king, King Jeongjo, with the calligraphy by Crown Prince Sado and the diary. It is unclear if the book Ham Jeonghui presented him was the same as the extant version of Ilgi. Nonetheless, considering the situation at the time when King Jeongjo was pursuing several projects to honor his father Sado, it is highly probable that Ilgi was produced during the reign of King Jeongjo. The periods of presenting the calligraphy and the diary respectively overlapped with the production of Hyeollyungwon, the royal tomb of Crown Prince Sado, and Sado's sixtieth birthday. Therefore, is it considered reasonable that Ham Jeonghui produced Ilgi to promote his own social ambitions.

Mechanism of steel pipe reinforcement grouting based on tunnel field measurement results (터널 현장 계측결과를 통한 강관보강 그라우팅의 거동 메커니즘)

  • Shin, Hyunkang;Jung, Hyuksang;Lee, Yong-joo;Kim, Nag-young;Ko, Sungil
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.23 no.3
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    • pp.133-149
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    • 2021
  • This study aims to report the behavioral mechanism of steel pipe reinforcement grouting, which is being actively used to ensure the stability of the excavation surface during tunnel excavation, based on measurements taken at the actual site. After using a 12 m steel pipe attached with a shape displacement meter and a strain gauge to reinforce the actual tunnel surface, behavioral characteristics were identified by analyzing the measured deformation and stress of the steel pipe. Taking into account that the steel pipes were overlapped every 6 m, the measured data up to 7 m of excavation were used. In addition, the behavioral characteristics of the steel pipe reinforcement according to the difference in strength were also examined by applying steel pipes with different allowable stresses (SGT275 and SGT550). As a result of analyzing the behavior of steel pipes for 7 hours after the first excavation for 1 m and before proceeding with the next excavation, the stress redistribution due to the arching effect caused by the excavation relaxation load was observed. As excavation proceeded by 1 m, the excavated section exhibited the greatest deformation during excavation of 4 to 6 m due to the stress distribution of the three-dimensional relaxation load, and deformation and stress were generated in the steel pipe installed in the ground ahead of the tunnel face. As a result of comparing the behavior of SGT275 steel pipe (yield strength 275 MPa) and SGT550 steel pipe (yield strength 550 MPa), the difference in the amount of deformation was up to 18 times and the stress was up to 12 times; the stronger the steel pipe, the better it was at responding to the relaxation load. In this study, the behavior mechanism of steel pipe reinforcement grouting in response to the arching effect due to the relaxation load was identified based on the measured data during the actual tunnel excavation, and the results were reported.