A Deep Learning Based Approach to Recognizing Accompanying Status of Smartphone Users Using Multimodal Data (스마트폰 다종 데이터를 활용한 딥러닝 기반의 사용자 동행 상태 인식)
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- Journal of Intelligence and Information Systems
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- v.25 no.1
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- pp.163-177
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- 2019
As smartphones are getting widely used, human activity recognition (HAR) tasks for recognizing personal activities of smartphone users with multimodal data have been actively studied recently. The research area is expanding from the recognition of the simple body movement of an individual user to the recognition of low-level behavior and high-level behavior. However, HAR tasks for recognizing interaction behavior with other people, such as whether the user is accompanying or communicating with someone else, have gotten less attention so far. And previous research for recognizing interaction behavior has usually depended on audio, Bluetooth, and Wi-Fi sensors, which are vulnerable to privacy issues and require much time to collect enough data. Whereas physical sensors including accelerometer, magnetic field and gyroscope sensors are less vulnerable to privacy issues and can collect a large amount of data within a short time. In this paper, a method for detecting accompanying status based on deep learning model by only using multimodal physical sensor data, such as an accelerometer, magnetic field and gyroscope, was proposed. The accompanying status was defined as a redefinition of a part of the user interaction behavior, including whether the user is accompanying with an acquaintance at a close distance and the user is actively communicating with the acquaintance. A framework based on convolutional neural networks (CNN) and long short-term memory (LSTM) recurrent networks for classifying accompanying and conversation was proposed. First, a data preprocessing method which consists of time synchronization of multimodal data from different physical sensors, data normalization and sequence data generation was introduced. We applied the nearest interpolation to synchronize the time of collected data from different sensors. Normalization was performed for each x, y, z axis value of the sensor data, and the sequence data was generated according to the sliding window method. Then, the sequence data became the input for CNN, where feature maps representing local dependencies of the original sequence are extracted. The CNN consisted of 3 convolutional layers and did not have a pooling layer to maintain the temporal information of the sequence data. Next, LSTM recurrent networks received the feature maps, learned long-term dependencies from them and extracted features. The LSTM recurrent networks consisted of two layers, each with 128 cells. Finally, the extracted features were used for classification by softmax classifier. The loss function of the model was cross entropy function and the weights of the model were randomly initialized on a normal distribution with an average of 0 and a standard deviation of 0.1. The model was trained using adaptive moment estimation (ADAM) optimization algorithm and the mini batch size was set to 128. We applied dropout to input values of the LSTM recurrent networks to prevent overfitting. The initial learning rate was set to 0.001, and it decreased exponentially by 0.99 at the end of each epoch training. An Android smartphone application was developed and released to collect data. We collected smartphone data for a total of 18 subjects. Using the data, the model classified accompanying and conversation by 98.74% and 98.83% accuracy each. Both the F1 score and accuracy of the model were higher than the F1 score and accuracy of the majority vote classifier, support vector machine, and deep recurrent neural network. In the future research, we will focus on more rigorous multimodal sensor data synchronization methods that minimize the time stamp differences. In addition, we will further study transfer learning method that enables transfer of trained models tailored to the training data to the evaluation data that follows a different distribution. It is expected that a model capable of exhibiting robust recognition performance against changes in data that is not considered in the model learning stage will be obtained.
1. Objective of the Study The objective of the study was to make fundamental suggestions for drawing a forest insurance system applicable in Korea by investigating forest insurance systems undertaken in foreign countries, analyzing the forest hazards occurred in entire forests of Korea in the past, and hearing the opinions of people engaged in forestry. 2. Methods of the Study First, reference studies on insurance at large as well as on forest insurance were intensively made to draw the characteristics of forest insurance practiced in main forestry countries, Second, the investigations of forest hazards in Korea for the past ten years were made with the help of the Office of Forestry. Third, the questionnaires concerning forest insurance were prepared and delivered at random to 533 personnel who are working at different administrative offices of forestry, forest stations, forest cooperatives, colleges and universities, research institutes, and fire insurance companies. Fourth, fifty three representative forest owners in the area of three forest types (coniferous, hardwood, and mixed forest), a representative region in Kyonggi Province out of fourteen collective forest development programs in Korea, were directly interviewed with the writer. 3. Results of the Study The rate of response to the questionnaire was 74.40% as shown in the table 3, and the results of the questionaire were as follows: (% in the parenthes shows the rates of response; shortages in amount to 100% were due to the facts of excluding the rates of response of minor respondents). 1) Necessity of forest insurance The respondents expressed their opinions that forest insurance must be undertaken to assure forest financing (5.65%); for receiving the reimbursement of replanting costs in case of damages done (35.87%); and to protect silvicultural investments (46.74%). 2) Law of forest insurance Few respondents showed their views in favor of applying the general insurance regulations to forest insurance practice (9.35%), but the majority of respondents were in favor of passing a special forest insurance law in the light of forest characteristics (88.26%). 3) Sorts of institutes to undertake forest insurance A few respondents believed that insurance companies at large could take care of forest insurance (17.42%); forest owner's mutual associations would manage the forest insurance more effectively (23.53%); but the more than half of the respondents were in favor of establishing public or national forest insurance institutes (56.18%). 4) Kinds of risks to be undertaken in forest insurance It would be desirable that the risks to be undertaken in forest insurance be limited: To forest fire hazards only (23.38%); to forest fire hazards plus damages made by weather (14.32%); to forest fire hazards, weather damages, and insect damages (60.68%). 5) Objectives to be insured It was responded that the objectives to be included in forest insurance should be limited: (1) To artificial coniferous forest only (13.47%); (2) to both coniferous and broad-leaved artificial forests (23.74%); (3) but the more than half of the respondents showed their desire that all the forests regardless of species and the methods of establishment should be insured (61.64%). 6) Range of risks in age of trees to be included in forest insurance The opinions of the respondents showed that it might be enough to insure the trees less than ten years of age (15.23%); but it would be more desirous of taking up forest trees under twenty years of age (32.95%); nevertheless, a large number of respondents were in favor of underwriting all the forest trees less than fourty years of age (46.37%). 7) Term of a forest insurance contract Quite a few respondents favored a contract made on one year basis (31.74%), but the more than half of the respondents favored the contract made on five year bases (58.68%). 8) Limitation in a forest insurance contract The respondents indicated that it would be desirable in a forest insurance contract to exclude forests less than five hectars (20.78%), but more than half of the respondents expressed their opinions that forests above a minimum volume or number of trees per unit area should be included in a forest insurance contract regardless of the area of forest lands (63.77%). 9) Methods of contract Some responded that it would be good to let the forest owners choose their forests in making a forest insurance contract (32.13%); others inclined to think that it would be desirable to include all the forests that owners hold whenerver they decide to make a forest insurance contract (33.48%); the rest responded in favor of forcing the owners to buy insurance policy if they own the forests that were established with subsidy or own highly vauable growing stock (31.92%) 10) Rate of premium The responses were divided into three categories: (1) The rate of primium is to be decided according to the regional degree of risks(27.72%); (2) to be decided by taking consideration both regional degree of risks and insurable values(31.59%); (3) and to be decided according to the rate of risks for the entire country and the insurable values (39.55%). 11) Payment of Premium Although a few respondents wished to make a payment of premium at once for a short term forest insurance contract, and an annual payment for a long term contract (13.80%); the majority of the respondents wished to pay the premium annually regardless of the term of contract, by employing a high rate of premium on a short term contract, but a low rate on a long term contract (83.71%). 12) Institutes in charge of forest insurance business A few respondents showed their desire that forest insurance be taken care of at the government forest administrative offices (18.75%); others at insurance companies (35.76%); but the rest, the largest number of the respondents, favored forest associations in the county. They also wanted to pay a certain rate of premium to the forest associations that issue the insurance (44.22%). 13) Limitation on indemnity for damages done In limitation on indemnity for damages done, the respondents showed a quite different views. Some desired compesation to cover replanting costs when young stands suffered damages and to be paid at the rate of eighty percent to the losses received when matured timber stands suffered damages(29.70%); others desired to receive compensation of the actual total loss valued at present market prices (31.07%); but the rest responded in favor of compensation at the present value figured out by applying a certain rate of prolongation factors to the establishment costs(36.99%). 14) Raising of funds for forest insurance A few respondents hoped to raise the fund for forest insurance by setting aside certain amount of money from the indemnity paid (15.65%); others wished to raise the fund by levying new forest land taxes(33.79%); but the rest expressed their hope to raise the fund by reserving certain amount of money from the surplus money that was saved due to the non-risks (44.81%). 15) Causes of fires The main causes of forest fires 6gured out by the respondents experience turned out to be (1) an accidental fire, (2) cigarettes, (3) shifting cultivation. The reponses were coincided with the forest fire analysis made by the Office of Forestry. 16) Fire prevention The respondents suggested that the most important and practical three kinds of forest fire prevention measures would be (1) providing a fire-break, (2) keeping passers-by out during the drought seasons, (3) enlightenment through mass communication systems. 4. Suggestions The writer wishes to present some suggestions that seemed helpful in drawing up a forest insurance system by reviewing the findings in the questionaire analysis and the results of investigations on forest insurance undertaken in foreign countries. 1) A forest insurance system designed to compensate the loss figured out on the basis of replanting cost when young forest stands suffered damages, and to strengthen credit rating by relieving of risks of damages, must be put in practice as soon as possible with the enactment of a specifically drawn forest insurance law. And the committee of forest insurance should be organized to make a full study of forest insurance system. 2) Two kinds of forest insurance organizations furnishing forest insurance, publicly-owned insurance organizations and privately-owned, are desirable in order to handle forest risks properly. The privately-owned forest insurance organizations should take up forest fire insurance only, and the publicly-owned ought to write insurance for forest fires and insect damages. 3) The privately-owned organizations furnishing forest insurance are desired to take up all the forest stands older than twenty years; whereas, the publicly-owned should sell forest insurance on artificially planted stands younger than twenty years with emphasis on compensating replanting costs of forest stands when they suffer damages. 4) Small forest stands, less than one hectare holding volume or stocked at smaller than standard per unit area are not to be included in a forest insurance writing, and the minimum term of insuring should not be longer than one year in the privately-owned forest insurance organizations although insuring period could be extended more than one year; whereas, consecutive five year term of insurance periods should be set as a mimimum period of insuring forest in the publicly-owned forest insurance organizations. 5) The forest owners should be free in selecting their forests in insuring; whereas, forest owners of the stands that were established with subsidy should be required to insure their forests at publicly-owned forest insurance organizations. 6) Annual insurance premiums for both publicly-owned and privately-owned forest insurance organizations ought to be figured out in proportion to the amount of insurance in accordance with the degree of risks which are grouped into three categories on the basis of the rate of risks throughout the country. 7) Annual premium should be paid at the beginning of forest insurance contract, but reduction must be made if the insuring periods extend longer than a minimum period of forest insurance set by the law. 8) The compensation for damages, the reimbursement, should be figured out on the basis of the ratio between the amount of insurance and insurable value. In the publicly-owned forest insurance system, the standard amount of insurance should be set on the basis of establishment costs in order to prevent over-compensation. 9) Forest insurance business is to be taken care of at the window of insurance com pnies when forest owners buy the privately-owned forest insurance, but the business of writing the publicly-owned forest insurance should be done through the forest cooperatives and certain portions of the premium be reimbursed to the forest cooperatives. 10) Forest insurance funds ought to be reserved by levying a property tax on forest lands. 11) In order to prevent forest damages, the forest owners should be required to report forest hazards immediately to the forest insurance organizations and the latter should bear the responsibility of taking preventive measures.
AirAsia QZ8501 Jet departed from Juanda International Airport in, Surabaya, Indonesia at 05:35 on Dec. 28, 2014 and was scheduled to arrive at Changi International Airport in Singapore at 08:30 the same day. The aircraft, an Airbus A320-200 crashed into the Java Sea on Dec. 28, 2014 carrying 162 passengers and crew off the coast of Indonesia's second largest city Surabaya on its way to Singapore. Indonesia's AirAsia jet carrying 162 people lost contact with ground control on Dec. 28, 2014. The aircraft's debris was found about 66 miles from the plane's last detected position. The 155 passengers and seven crew members aboard Flight QZ 8501, which vanished from radar 42 minutes after having departed Indonesia's second largest city of Surabaya bound for Singapore early Dec. 28, 2014. AirAsia QZ8501 had on board 137 adult passengers, 17 children and one infant, along with two pilots and five crew members in the aircraft, a majority of them Indonesian nationals. On board Flight QZ8501 were 155 Indonesian, three South Koreans, and one person each from Singapore, Malaysia and the UK. The Malaysia Airlines Flight 370 departed from Kuala Lumpur International Airport on March 8, 2014 at 00:41 local time and was scheduled to land at Beijing's Capital International Airport at 06:30 local time. Malaysia Airlines also marketed as China Southern Airlines Flight 748 (CZ748) through a code-share agreement, was a scheduled international passenger flight that disappeared on 8 March 2014 en route from Kuala Lumpur International Airport to Beijing's Capital International Airport (a distance of 2,743 miles: 4,414 km). The aircraft, a Boeing 777-200ER, last made contact with air traffic control less than an hour after takeoff. Operated by Malaysia Airlines (MAS), the aircraft carried 12 crew members and 227 passengers from 15 nations. There were 227 passengers, including 153 Chinese and 38 Malaysians, according to records. Nearly two-thirds of the passengers on Flight 370 were from China. On April 5, 2014 what could be the wreckage of the ill-fated Malaysia Airlines was found. What appeared to be the remnants of flight MH370 have been spotted drifting in a remote section of the Indian Ocean. Compensation for loss of life is vastly different between US. passengers and non-U.S. passengers. "If the claim is brought in the US. court, it's of significantly more value than if it's brought into any other court." Some victims and survivors of the Indonesian and Malaysia airline's air crash case would like to sue the lawsuit to the United States court in order to receive a larger compensation package for damage caused by an accident that occurred in the sea of Java sea and the Indian ocean and rather than taking it to the Indonesian or Malaysian court. Though each victim and survivor of the Indonesian and Malaysia airline's air crash case will receive an unconditional 113,100 Unit of Account (SDR) as an amount of compensation for damage from Indonesia's AirAsia and Malaysia Airlines in accordance with Article 21, 1 (absolute, strict, no-fault liability system) of the 1999 Montreal Convention. But if Indonesia AirAsia airlines and Malaysia Airlines cannot prove as to the following two points without fault based on Article 21, 2 (presumed faulty system) of the 1999 Montreal Convention, AirAsia of Indonesiaand Malaysia Airlines will be burdened the unlimited liability to the each victim and survivor of the Indonesian and Malaysia airline's air crash case such as (1) such damage was not due to the negligence or other wrongful act or omission of the air carrier or its servants or agents, or (2) such damage was solely due to the negligence or other wrongful act or omission of a third party. In this researcher's view for the aforementioned reasons, and under the laws of China, Indonesia, Malaysia and Korea the Chinese, Indonesian, Malaysia and Korean, some victims and survivors of the crash of the two flights are entitled to receive possibly from more than 113,100 SDR to 5 million US$ from the two airlines or from the Aviation Insurance Company based on decision of the American court. It could also be argued that it is reasonable and necessary to revise the clause referring to bodily injury to a clause mentioning personal injury based on Article 17 of the 1999 Montreal Convention so as to be included the mental injury and condolence in the near future.
Experiments and investigations were done basically and practically for the purpose of labor saving in paddy rice cultivation especially on Homizil i.e. hoeing and herbicide, 1969. 8 concrete tanks were established on the open base of Keon Kuk University for comparison of percolation, dissolved oxygen and yield test of rice in the paddy plot of tank. The dimension of the bottom of each tank is square meter. Each of the 4 of the 8 tanks is 21cm in height and each of the remaining 4 tanks is 36cm. Each tank has a system that comprises 2 sets of tubes, each of which has 20 holes of 5mm in diameter scattered every side and is covered with nylon cloth taking water in the tank. One set consists of 4 P.V.C tubes. The first set is situated 8cm below the top of the tank and the second set is located at bottom layer inside the tank. The 4 tubes of each set are combined together and led to the glass tube which protects from inside to outside. And this inside-outside glass tube is connected to the small rubber tube. Also a glass tube is set 4cm below the top of the tank. Paddy loam was filled on sand in each of the tanks in the soil depth of either 15cm or 30cm. The depth of sand was 5cm in the soil depth of 15cm and 10cm in the soil depth of 30cm. (Fig. 1, 2 and 3). The paddy rice was grown in the tank. The percolation of water, the dissolved oxygen and the yield of rice were observed in the tank. And the dissolved oxygen was detected by Winkler method. A sandy paddy field of heavy percolation was selected at the field of the National Agricultural Material Inspection Center in Seoul. It was divided into 9 plots. These plots were given 3 treatments: (A) not hoeing, (B) hoeing one time and (C) hoeing two times. These treatments were replicated 3 times along the latin square design. The paddy rice was grown and sprayed with Stam F-34 in the all plots for the purpose of killing weeds before hoeing. The two types of paddy of field i.e. one for normal percolation and the other for ill drainage were selected at Iri Crop Experiment Station, Jeonla-Bukdo. Each field was divided into 24 plots for 8 treatments. They are: (A) not hoeing; (B) hoeing one time; (C) hoeing two times; (D) not hoeing but treating with herbicide, Pamcon; (E) hoeing one time and weeding two times also treating with herbicide, Pamcon; (F) hoeing two times and weeding one time a], o treating with herbicide, Pamcon; (G) hoeing two times and weeding two times also treating with herbicide, Pamcon, ; (H) usual manner. The labor hours and expenses needed for weeding in the paddy by hoeing were investigated in a farmer at Suwon and the price of herbicide and the yield of rice were taken out at Iri, Jeonla-Bukdo. The results obtained from the above experiments and investigations are as follows: 1. The relationship between percolation and dissolved oxygen shows that a very small amount of oxygen is detected in the soil water under 2cm below surface of earth in the paddy even when percolation is over 4.0cm per 24 hours (Tab. 1). 2. The relationship between percolation and yield of rice shows that the yield of rice increases in the percolation of 0cm and 1.5cm per 24 hours and decreases in the percolation of 2.5cm and 3.4cm in the plot of the 15cm ploughing depth and increases in the percolation of 1.4cm and 3.0cm and decreases in the percolation of 0cm and 4.0cm in the plot of 30cm ploughing depth (Tab. 1 and Fig. 5). 3. The yield of paddy weeded with Stam F-34 in the sandy field of heavy percolation in Seoul was 3.02 tons in the plot of not hoeing, 2.99 tons in hoeing one time and 3.05 tons in hoeing two times per hectare (Tab. 5). 4.1). 4. 1) The yield of rice per 10 ares in the field of normal percolation at Iri was 338kg in not hoeing, 379kg in hoeing one time, 383kg in hoeing two times, 413kg in spraying herbicide, Pamcon, and not hoeing, 433kg in spraying herbicide, Pamcon, and hoeing one time and weeding two times, 399kg in spraying herbicide, Pamcon, and hoeing two times and weeding one time, 420kg in spraying herbicide, Pamcon, and hoeing two times and weeding two times and 418kg in usual manner (Tab. 6-1). 2) The yield of rice per 10 ares in the field of ill drainage at Iri was 323kg in not hoeing, 363kg in hoeing one time, 342kg in hoeing two times, 388kg in spraying herbicide, Pamcon, and not hoeing, 425kg in spraying herbicide, Pamcon, and hoeing one time and weeding two times, 427kg in spraying herbicide, Pamcon, and hoeing two times and weeding one time, 449kg in spraying herbicide, Pamcon, and hoeing two times and weeding two times and 412kg in usual manner (Tab. 6-2). 5. 1) The labor hours for weeding by hoeing was 37.1 hours but 53.5 hours if hours for meal, smoking and so on are included, and the expenses including labor cost needed for weeding by hoeing in the paddy rice was 2, 346 Won per 10 ares at Suwon (Tab. 7). 2) The labor hours for weeding by spraying herbicide with hand sprayer in the paddy rice was about 5 hours per 10 ares at Suwon and the expenses for weeding by spraying herbicide in the paddy rice was 750 Won but 1130 Won if the loss by decrement of rice in the paddy field of ill drainage per 10 ares is calculated in estimation at Iri (Tab. 8). From these observations and investigations it is known that using of some kinds of herbicides Saves labor and expenses of weeding, almost without giving damages to the rice itself, in the field of normal or heavy percolation comparing usual manner of hoeing.
This study investigates the current preservation and management of four records and documentary heritage in Korea that is in the UNESCO's Memory of the World Register. The study analyzes their problems and corresponding solutions in digitizing those world records heritages. This study also reviews additional four documentary books in Korea that are in the wish list to add to UNESCO's Memory of the World Register. This study is organized as the following: Chapter 2 examines the value and meanings of world records and documentary heritage in Korea. The registry requirements and procedures of UNESCO's Memory of the World Register are examined. The currently registered records of Korea include Hunmin-Chongum, the Annals of the Choson Dynasty, the Diaries of the Royal Secretariat (Seungjeongwon Ilgi), and Buljo- Jikji-Simche-Yojeol (vol. II). These records heritage's worth and significance are carefully analyzed. For example, Hunmin-Chongum("訓民正音") is consisted of unique and systematic letters. Letters were delicately explained with examples in its original manual at the time of letter's creation, which is an unparalleled case in the world documentary history. The Annals of the Choson Dynasty("朝鮮王朝實錄") are the most comprehensive historic documents that contain the longest period of time in history. Their truthfulness and reliability in describing history give credits to the annals. The Royal Secretariat Diary (called Seungjeongwon-Ilgi("承政院日記")) is the most voluminous primary resources in history, superior to the Annals of Choson Dynasty and Twenty Five Histories in China. Jikji("直指") is the oldest existing book published by movable metal print sets in the world. It evidences the beginning of metal printing in the world printing history and is worthy of being as world heritage. The review of the four registered records confirms that they are valuable world documentary heritage that transfers culture of mankind to next generations and should be preserved carefully and safely without deterioration or loss. Chapter 3 investigates the current status of preservation and management of three repositories that store the four registered records in Korea. The repositories include Kyujanggak Archives in Seoul National University, Pusan Records and Information Center of National Records and Archives Service, and Gansong Art Museum. The quality of their preservation and management are excellent in all of three institutions by the following aspects: 1) detailed security measures are close to perfection 2) archiving practices are very careful by using a special stack room in steady temperature and humidity and depositing it in stack or archival box made of paulownia tree and 3) fire prevention, lighting, and fumigation are thoroughly prepared. Chapter 4 summarizes the status quo of digitization projects of records heritage in Korea. The most important issue related to digitization and database construction on Korean records heritage is likely to set up the standardization of digitization processes and facilities. It is urgently necessary to develop comprehensive standard systems for digitization. Two institutions are closely interested in these tasks: 1) the National Records and Archives Service experienced in developing government records management systems; and 2) the Cultural Heritage Administration interested in digitization of Korean old documents. In collaboration of these two institutions, a new standard system will be designed for digitizing records heritage on Korean Studies. Chapter 5 deals with additional Korean records heritage in the wish list for UNESCO's Memory of the World Register, including: 1) Wooden Printing Blocks(經板) of Koryo-Taejangkyong(高麗大藏經) in Haein Temple(海印寺); 2) Dongui-Bogam("東醫寶鑑") 3) Samguk-Yusa("三國遺事") and 4) Mugujeonggwangdaedaranigyeong. Their world value and importance are examined as followings. Wooden Printing Blocks of Koryo-Taejangkyong in Haein Temple is the worldly oldest wooden printing block of cannon of Buddhism that still exist and was created over 750 years ago. It needs a special conservation treatment to disinfect germs residing in surface and inside of wooden plates. Otherwise, it may be damaged seriously. For its effective conservation and preservation, we hope that UNESCO and Government will schedule special care and budget and join the list of Memory of the Word Register. Dongui-Bogam is the most comprehensive and well-written medical book in the Korean history, summarizing all medical books in Korea and China from the Ancient Times through the early 17th century and concentrating on Korean herb medicine and prescriptions. It is proved as the best clinical guidebook in the 17th century for doctors and practitioners to easily use. The book was also published in China and Japan in the 18th century and greatly influenced the development of practical clinic and medical research in Asia at that time. This is why Dongui Bogam is in the wish list to register to the Memory of the World. Samguk-Yusa is evaluated as one of the most comprehensive history books and treasure sources in Korea, which illustrates foundations of Korean people and covers histories and cultures of ancient Korean peninsula and nearby countries. The book contains the oldest fixed form verse, called Hyang-Ka(鄕歌), and became the origin of Korean literature. In particular, the section of Gi-ee(紀異篇) describes the historical processes of dynasty transition from the first dynasty Gochosun(古朝鮮) to Goguryeo(高句麗) and illustrates the identity of Korean people from its historical origin. This book is worthy of adding to the Memory of the World Register. Mugujeonggwangdaedaranigyeong is the oldest book printed by wooden type plates, and it is estimated to print in between 706 and 751. It contains several reasons and evidence to be worthy of adding to the list of the Memory of the World. It is the greatest documentary heritage that represents the first wooden printing book that still exists in the world as well as illustrates the history of wooden printing in Korea.