• Title/Summary/Keyword: cross-correlation method

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Korean Word Sense Disambiguation using Dictionary and Corpus (사전과 말뭉치를 이용한 한국어 단어 중의성 해소)

  • Jeong, Hanjo;Park, Byeonghwa
    • Journal of Intelligence and Information Systems
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    • v.21 no.1
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    • pp.1-13
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    • 2015
  • As opinion mining in big data applications has been highlighted, a lot of research on unstructured data has made. Lots of social media on the Internet generate unstructured or semi-structured data every second and they are often made by natural or human languages we use in daily life. Many words in human languages have multiple meanings or senses. In this result, it is very difficult for computers to extract useful information from these datasets. Traditional web search engines are usually based on keyword search, resulting in incorrect search results which are far from users' intentions. Even though a lot of progress in enhancing the performance of search engines has made over the last years in order to provide users with appropriate results, there is still so much to improve it. Word sense disambiguation can play a very important role in dealing with natural language processing and is considered as one of the most difficult problems in this area. Major approaches to word sense disambiguation can be classified as knowledge-base, supervised corpus-based, and unsupervised corpus-based approaches. This paper presents a method which automatically generates a corpus for word sense disambiguation by taking advantage of examples in existing dictionaries and avoids expensive sense tagging processes. It experiments the effectiveness of the method based on Naïve Bayes Model, which is one of supervised learning algorithms, by using Korean standard unabridged dictionary and Sejong Corpus. Korean standard unabridged dictionary has approximately 57,000 sentences. Sejong Corpus has about 790,000 sentences tagged with part-of-speech and senses all together. For the experiment of this study, Korean standard unabridged dictionary and Sejong Corpus were experimented as a combination and separate entities using cross validation. Only nouns, target subjects in word sense disambiguation, were selected. 93,522 word senses among 265,655 nouns and 56,914 sentences from related proverbs and examples were additionally combined in the corpus. Sejong Corpus was easily merged with Korean standard unabridged dictionary because Sejong Corpus was tagged based on sense indices defined by Korean standard unabridged dictionary. Sense vectors were formed after the merged corpus was created. Terms used in creating sense vectors were added in the named entity dictionary of Korean morphological analyzer. By using the extended named entity dictionary, term vectors were extracted from the input sentences and then term vectors for the sentences were created. Given the extracted term vector and the sense vector model made during the pre-processing stage, the sense-tagged terms were determined by the vector space model based word sense disambiguation. In addition, this study shows the effectiveness of merged corpus from examples in Korean standard unabridged dictionary and Sejong Corpus. The experiment shows the better results in precision and recall are found with the merged corpus. This study suggests it can practically enhance the performance of internet search engines and help us to understand more accurate meaning of a sentence in natural language processing pertinent to search engines, opinion mining, and text mining. Naïve Bayes classifier used in this study represents a supervised learning algorithm and uses Bayes theorem. Naïve Bayes classifier has an assumption that all senses are independent. Even though the assumption of Naïve Bayes classifier is not realistic and ignores the correlation between attributes, Naïve Bayes classifier is widely used because of its simplicity and in practice it is known to be very effective in many applications such as text classification and medical diagnosis. However, further research need to be carried out to consider all possible combinations and/or partial combinations of all senses in a sentence. Also, the effectiveness of word sense disambiguation may be improved if rhetorical structures or morphological dependencies between words are analyzed through syntactic analysis.

한국 청소년의 약물남용과 비행행위

  • 김성이
    • Korea journal of population studies
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    • v.11 no.2
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    • pp.54-66
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    • 1988
  • I. Introduction Since the 1970's drug abuse among young people has increasingly become a social problem in Korea. In the 1980's, drug abuse, especially glue sniffing, has become the cause of many unfortunated incidents resulting in harm to others as well as the abusers themselves. Taking into consideration of the seriousness of this problem, the Republic of Korea National Red Cross initiated a nation-wide research programme, to understand the present situation and to raise the level of public awareness. The goal of this research was to begin a nation - wide campaign against drug abuse. The research team was composed of the Advisary Committee members and the staff of the Youth Department of the Republic of Korea National Red Cross. The data were collected in February 1988 with the collaboration of the staff and volunteers in the local Chapters. The respondents were allocated nation-wide by the quota sampling method. The questionnaires were distributed to the respondents in three groups :2, 700 to junior and senior high school students, 605 to working youths, and 916 to delinquent youths. A total of 4, 221 questionnaires were collected. II. Characteristics of the Respondents The respondents in each group were selected evenly from rural and urban areas. The general characteristics of the respondents can be described as follow: in case of students, the proportions between male and female respondents, and between senior high school and junior high school students were almost evenly distributed. In case of working youths, the proportion of females (80.5%) was higher than those of the students and the delinquents groups. Delinquent youths were defined as those currently being under custody of the centers for juvenile delinquents. Of this number, 38.8% and 68.2% were junior and senior high school drop-outs respectively. The majority of them (92.6%) were male. As for the family background of the respondents, the proportion of those residing in poverty - stricken areas, and the proportion of those from broken families were higher in case of working youths and delinquent youths than those in case of students. III. Present Patterns of Drug Abuse The following summarizes the presents of drug abuse, as tabulated from the results of the survey. 1. Smoking The percentage of youths who smoke was 36% in the student group, 32% m the working youths group, and 94.4% in the delinquent youths group. 2. Alcohol 50.3% of students, 71.6% of working youths, and 93.3% of delinquent youths has experienced drinking alcohol beverages. 3. Tonic: non - alcoholic, caffeinated beverages popular in Korea and Japan The percentage of those who have used tonic at least once was over 90% in all of the three groups. 4. Sedative About 70% of each group has used sedative with the proportion of working youths use higher than those in other groups. 5. Stimulants Those who have used stimulants comprised around 15% in each group. 6. Tranquilizers Somewhat less than 5% of students and working youths, and 28% of delinquent youths, have used tranquilizers. 7. Hypnotics The users of hypnotics amounted to 0.4% of students, 2.6% of working youths and 7.1% of delinquent youths. 8. Marihuana Those who have used marihuana indicated 0.7% of students, 0.8% of working youths, and 13% of delinquent youths. 9. Glue-sniffing The percentage of glue-sniffing was 3.7%, 5% in the students group and in the youths group respectively, but the proportion was unusually high, at 40.7% in the delinquent youths group. From the results of the survey the present situation of drug abuse in Korea can be summarized as follows: 1. A high percentage of Korean youths have experienced smoking cigarettes and drinking alcoholic beverages. 2. Tonics (non - alcoholic, caffeinated beverages), antipyretic analgesics and stimulants quite regularly used. 3. Tranquilizers, hypnotics, marihuana and glue-sniffing are more widely used among delinquent youths than the other youths. From this fact, there exists a correlation between drug abuse and juvenile delinquency. IV. Time-series Analysis of the First Experience of Drug Abuse and Deviant Behaviour The respoundents were asked when they were first exposed to drugs and when they committed deviant acts. By calculating the average age of each experience, the following pattern was found (See Figure 1). Youths are first exposed to drugs by abuse of tonic(non - alcoholic, caffeinated beverages). At the age of 13, they amoke cigarettes, the use of antipyretic analgesics begins at 14 year old, while at the age of 15, they use tranquilizers, and at 16 hynotics. The period of drug abuse which starts from drinking caffeinated beverages and smoking cigarettes and ends in the use of hypnotics takes about three years. During this period, other delinquent behaviours begin to surface, that is, at the age of 13 when smoking cigarettes begins, the delinquent behaviour pattern starts with truancy. Next, they start taking money from others by using physical force. Prior to the age of 15, they are suspended from school, become hostile to adults, begin running away from home, and start using stimulants and alcohol. Soon they become involved even in glue-sniffing and in the use of marihuana. At the age of 15, they begin to see adult videos and carry weapons. Sexual promiscuity and usage of tranquilizers follows the viewing of adult videos. Consequently, by the time they reach the age of 16, they visit drinking establishments, and are picked up by police for committing delinquent acts. And finally, they come to use hypnotic - type drugs. From the above descriptions, drug abuse can be assumed to have a close correlation with delinquent behaviour. V. Social Factors Related to Drug Abuse As for the Korean youths, glue-sniffing is found to he related to aggressive delinquency, in such cases as run - aways, being picked up by the police, and taking money by force. Smoking cigarettes and drinking alcohol is found to be related to seeing adult videos and visiting drinking establishments. Hypnotics and marihuana were found to be representive of drugs which are related to degenerational delinquency, irrespective of social delinquency. The social factors connected with these drug abuse are as follows: 1. Individual factors Male students were more heavily involved in the usage of drug than females. Youths who do not attend church were more likely to be involved in drugs than those who attend. 2. Family factors The youths who were displeased with their mothers smoking and those who thought their parents did not love each other, or those whose parents had used drugs without prescription, were more likely to he drug users. 3. School factors Those youths who found school life boring, were unsuccessful in their studies, spend most of their time with friends, feel their teachers smoke too much, those who had a positive perception of their teachers smoking were likely to he drug users. To sum up, drug abusers depend on the influence of their parents, teachers and peers. IV. Reasons for Drug Abuse Korean students have mainly used drugs to release stress (42.8%), to stay awake (19.7%), and because of the easy accessibility of drugs( 16.6%). Other reasons are due to their ignorance of the side effects of the drugs (3.6%), natural curiosity (4.2%), and to increase strength(3.O%). From the above facts, the major reasons for drug abuse among Korean youths are to release stress and to stay awake in order to prepare exams. Furthermore, since drugs are readily available, we can conclude that drug abuse is caused by the school system(such as entrance exams) in Korea. VII. Conclusion Drug usage among Korean youths are relatively less common than those of western youths. In some cases, such as, glue-sniffing and use of stimulants, the pattern of drug abuse is found. Moreover, early drug abuse is evident, and it has a close connection with deviant behaviour, resulting in juvenile delinquency. Drug abuse cannot be attributed to any one social factor. Specifically, drug abuse depends on parents, peers, teachers and other members of the community, and also is influenced by social institutions such as the entrance exam system. Every person and organization concerned with youth must participate collectively in restraining drug abuse. Finally, it is suggested that social agencial working for youth welfare should make every effort to tackle this serious problem confronted by the Korean youths today.

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A Study on the Women's Need during early Postpartum (산욕 초기 여성의 간호 요구에 관한 연구)

  • Yoo, Eun-Kwang;Lee, Mi-Young;Kim, Jin-Hee;Sin, Chu-Kyung;Yoo, Soon-Jae;Ji, Soo-Kyung
    • Women's Health Nursing
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    • v.6 no.3
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    • pp.439-452
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    • 2000
  • This study sought to figure out women's needs during early postpartum for developing adequate nursing intervention toward postpartal women's healthy adaptation. A convenience sample of 89 women who are in the early postpartal period and admitted in a university hospital located in Seoul, Korea was studied from July 1, 1999 to August 13. 1999. 1. The age group of 26-30 years was 52.8% and the level of education above high school 91%. 67.6% of women had no job, 62.9% had experienced one time of delivery, and 52.8% had no experience of abortion. 2. 31.5% of women received prenatal education, 44.9% only postpartal education. 77.5% of women planned breast-feeding, and 53.9% of women had an experience of breast-feeding during hospital stay. For the feeling of confidence related to the self-care, 27% only expressed 'yes. I have' and 59.5% 'just a little bit'. For the feeling of confidence related to the baby rearing, 29.2% only expressed 'yes. I have' and 60.7% 'just a little bit'. 3. The rate of postpartal women's mother as a preferred non-professional care giver was the highest, 75.3%. The rate of the style of Sanhujori highly preferred and planned at this time was at postpartal women's maiden home or her home with mother, 58.4%, 47.7% respectively. It shows that women still wish to have traditional Sanhuiori at home. 4. The mean of nursing need of postpartal women was 4.25% and it means that universally the degree of nursing need during postpartum is still high. General nursing need (4.29) was higher than that of traditional Sanhujori (4.09), however, the need of Sanhujori is still high. 5. Specifically, the degree of nursing need according to the category of needs was 'educational need for baby rearing,' 4.43; 'emotional-psychological care', 4.41; 'environmental care,' 4.31; 'self-care,' 4.14; and 'physical care,' 3.85 in rank. The educational need core of the specific method about Sanhuiori (4.35) was second to the highest among 15 items of self-care. 6. The related factors to the degree of nursing need were age to physical care; educational level, plan of breast feeding and experience of breast feeding during hospital stay to emotional-psychological care; and the feeling of confidence in baby rearing to environmental care. 7. There was highly positive correlation between the degree of traditional Sanhujori need and general care need(r=.77). This result strongly reflects that there is a necessity of professional care givers' capability to consider the integrative care reflecting the socio-cultural need for women's healthy adaptation during postpartum. It provides a challenge to the professional care givers to research further on the effects of Sanhuiori on the health status, health recovery after abortion or delivery from the various aspects through the cross-sectional and longitudinal research for the refinement of the reality of Sanhuiori not only as cultural phenomenon but as an inseparable factor influencing on women's postpartal healthy adaptation and for the appropriateness of intervention and quality of care for desirable health outcome.

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Development and Evaluation of Traffic Conflict Criteria at an intersection (교차로 교통상충기준 개발 및 평가에 관한 연구)

  • 하태준;박형규;박제진;박찬모
    • Journal of Korean Society of Transportation
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    • v.20 no.2
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    • pp.105-115
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    • 2002
  • For many rears, traffic accident statistics are the most direct measure of safety for a signalized intersection. However it takes more than 2 or 3 yearn to collect certain accident data for adequate sample sizes. And the accident data itself is unreliable because of the difference between accident data recorded and accident that is actually occurred. Therefore, it is rather difficult to evaluate safety for a intersection by using accident data. For these reasons, traffic conflict technique(TCT) was developed as a buick and accurate counter-measure of safety for a intersection. However, the collected conflict data is not always reliable because there is absence of clear criteria for conflict. This study developed objective and accurate conflict criteria, which is shown below based on traffic engineering theory. Frist, the rear-end conflict is regarded, when the following vehicle takes evasive maneuver against the first vehicle within a certain distance, according to car-following theory. Second, lane-change conflict is regarded when the following vehicle takes evasive maneuver against first vehicle which is changing its lane within the minimum stopping distance of the following vehicle. Third, cross and opposing-left turn conflicts are regarded when the vehicle which receives green sign takes evasive maneuver against the vehicle which lost its right-of-way crossing a intersection. As a result of correlation analysis between conflict and accident, it is verified that the suggested conflict criteria in this study ave applicable. And it is proven that estimating safety evaluation for a intersection with conflict data is possible, according to the regression analysis preformed between accident and conflict, EPDO accident and conflict. Adopting the conflict criteria suggested in this study would be both quick and accurate method for diagnosing safety and operational deficiencies and for evaluation improvements at intersections. Further research is required to refine the suggested conflict criteria to extend its application. In addition, it is necessary to develope other types of conflict criteria, not included in this study, in later study.

Ultrastructrual Change of Myocardium in Open Cardiac Surgery with Cold Blood Cardioplegia (개심술 시 냉혈성 심정지액 사용에 따른 허혈 전후 심근 미세구조의 변화)

  • 김병호;김대현;공준혁;조준용;손윤경;이종태
    • Journal of Chest Surgery
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    • v.36 no.9
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    • pp.638-645
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    • 2003
  • The purposes of this study were to evaluate the effect of myocardial protection with our cold blood cardioplegic solution and to observe the relationship between ultrastructural study and other evaluation methods and its effectiveness. Material and Method: We evaluated the changes of myocardial ultrastructure using semi-quantitative scoring system, CK-MB fraction, SGOT and LDH1/LDH2, and EKG in 18 patients undergoing valvular heart surgery and coronary artery bypass grafting (CABG). Right atrial auricular biopsies were taken before the cardiopulmonary bypass (CPB) and shortly after the end of CPB. Myocardium-related serum enzymes & EKG were checked for 3 days of postoperative period and their postoperative peak enzyme value and observed new Q wave & ST segment elevation in EKG were choosen. Result: There were 8 males and 10 females, and their mean age was 55.6$\pm$13. Eight patients underwent valvular heart surgery and ten coronary artery bypass grafting, The mean CPB time was 119$\pm$29 minutes and the mean aortic cross-clamp (ACC) time was 75.4$\pm$24 minutes. Before the start of CPB, the mean mitochondrial score was 4.28$\pm$0.53 and after the end of CPB, it significantly increased to 2.35$\pm$0.79. There was no evidence of perioperative myocardial infarction in terms of myocardiumrelated serum enzyme value and Q wave and ST change in EKG. There was no significant relationship between pre-CPB and post-CPB mitochondrial score and the mean time of CPB and ACC, and the mean value of postoperative peak CK-MB, SGOT and LDH1/LDH2, but there was relatively positive correlation of CPB time with peak LDH1/LDH2. Conclusion: Despite the apparent satisfactory results in myocardium-related serum enzymes & EKG, with this study using the cold blood cardioplegic solution, there were many changes in myocardial ultrastructures, and more studies are needed to obtain further information.

Diameters of the Thoracic Aorta Measured with Multidetector Computed Tomography (다중검출 전산화 단층촬영을 이용하여 측정한 흉부대동맥의 직경)

  • Lee, Gun;Lim, Chang-Young;Lee, Hyeon-Jae
    • Journal of Chest Surgery
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    • v.42 no.1
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    • pp.79-86
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    • 2009
  • Background: Background: Computed tomography (CT) is the main tool for detecting abnormalities of the thoracic aorta, but conventional CT only shows the cross-sectional images. These CT images have some limitations fo accuratly measuring the thoracic aortic diameters at various levels. Multidetector computed tomography (MDCT) overcomes these limitations. We measured the thoracic aortic diameter perpendicular to the loop-shaped thoracic aortic course and this was studied in relation to age, gender, height, weight, the body surface area, the body mass index and the presence of hypertension. Material and Method: Thirty hundred thirty one patients (males: 141 patients and females: 190 patients) who had no abnormalities of the thoracic aorta were investigated using MDCT aortography. They were divided into three age categories: 20~39 years old, 40~59 years old and over age 60. The image was reformed with multiplanar reconstruction and the diameter of the aorta was measured perpendicular to the aortic course at 5 anatomic segments. Level A was the mid-ascending aorta, level B was the distal ascending aorta, level C was the aortic arch, level D was the aortic isthmus and level E was the mid-descending aorta. Result: The mean age was 49.5 years old for males and 54.9 years old for females (p<0.05). The mean diameter of the thoracic aorta at level A was 31.1 mm, that at level B was 30.2 mm, that at level C was 26.5 mm, that at level D was 24.0 mm and that at level E was 22.6 mm. The diameters at all the levels were gradually increased with age. Hypertensive patients had larger diameters than did the non-hypertensive population. There was a positive correlation between the ascending aortic diameter (levels A&B) and height and the body surface area, but there were no statistical differences at the aortic arch (level C) and the descending aorta (levels D&E). There were no statistical differences of the weight and body mass index at all levels. Conclusion: The diameters of the thoracic aortas were directly correlated with gender, age and hypertension. Height and the body surface area were only correlated with the ascending aorta. Weight and the body mass index have no statistical difference at all levels. We measured the age related thoracic aortic diameters and the upper normal limits and we provide this data as reference values for the thoracic aortic diameter in the Korean population.

Serum ghrelin and leptin concentrations in children with cancer : comparisons with normal children (소아 종양 환아의 혈중 Ghrelin과 Leptin의 농도: 정상 소아와 비교)

  • Park, So Hyun;Jung, Min Ho;Chung, Nac Gyun;Suh, Byung-Kyu;Lee, Byung Churl
    • Clinical and Experimental Pediatrics
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    • v.50 no.9
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    • pp.905-911
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    • 2007
  • Purpose : Ghrelin, being secreted from the stomach, stimulates growth hormone secretion and controls energy homeostasis by increasing appetite. Leptin, being secreted from the adipocytes, controls weight and energy homeostasis by decreasing appetite. Leptin concentration is reported to increase after childhood cancer therapy. This study was aimed to compare ghrelin and leptin concentrations in normal children and children who received cancer therapy. Methods : We enrolled forty-three patients who were diagnosed with cancer and received radiotherapy or chemotherapy during Dec. 2004 through Dec. 2005 in St. Marys hospital and Kangnam St. Marys hospital. Forty-five healthy children were selected as a control group whose age, gender, weight and height were similar to those of cancer group. The serum leptin and ghrelin concentrations were also measured by radioimmunoassay. Results : The cancer group showed higher BMI and leptin concentrations. The control group showed higher concentrations of ghrelin. Both control and cancer groups revealed positive correlations between leptin concentrations and BMI. Ghrelin concentrations in the control group showed negative correlations with age, height, weight and BMI but no significant correlation was found in the cancer group. All the parameters in the group treated with chemotherapy only were not different from those in the group treated with chemotherapy and irradiation. But the level of ghrelin in the acute myeloid leukemia group was much higher than those in the acute lymphoblastic leukemia group. Conclusion : Patients with pediatric cancer treatment have presented higher BMI and leptin concentrations but lower ghrelin concentrations than those in healthy children. Because of the relatively short duration and cross sectional method of the study, however, further long term and prospective study will be required in the future.

Studies on the growth duration and hybrid sterility in remote cross breeding of cultivated rice (수도원연품종간잡종에 있어서의 생육일수와 불임에 관한 연구)

  • Mun-Hue Heu
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.4 no.1
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    • pp.31-71
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    • 1968
  • To clarify the breeding behavior of the hybrids between tropical and temperate area rice varieties, investigations were made on heading days and grain sterility. In this study, crosses were made in half way diallel involving 7 varieties: 2 photoperied sensitive Indicas, 2 less sensitive intermediate Indicas, 1 Ponlai Japonica and 2 high temperature sensitive Japonicas. The parents and $F_1$s were grown under 10 hours and 14 hours daylength controlled conditions at both IRRI(International Rice Research Institute, N$14^{\circ}$17') and Suwon(N$37^{\circ}$16'). F2s with their parents were grown at IRRI in the short day season, and at Suwon under natural conditions. Fa lines with their parents were grown at Suwon under natural conditions. Observations were made for heading days and sterility. The results are summarized as follow; 1. Heading days : 1. For the $F_1$s, earliness showed dominance or overdominance to lateness under the 10 hours condition, and dominance or partial dominance under the 14 hours conditions, at both IRRI and Suwon. 2. For the $F_2$s grown at IRRI during the shortday season earliness appeared to be dominant over lateness and segregation was not distinct and continuous. In the early season culture of $F_2$s at Suwon earliness showed partial dominance or was intermediate. In the proper season culture of $F_2$s lateness showed partial dominance or was intermediate. 3. In the combinations between late parental varieties which do not head at Suwon, transgressive segregants bearing effective panicles were obtained. 4. The crosses of parental varieties having long basic vegetative growth duration showed bigger variance in heading days, and significant correlation was found between of parental varieties and the mean coefficient of variance for parental arrays. 5. The means of heading days of F2 populations were significantly correlated with those of $F_1$ or mid-parents. The means of F 8 lines were also highly correlated with the means of $F_2$s, but, the means of $F_3$ lines grown at Suwon and of their parental $F_2$ individual, grown at IRRI were not correlated. 6. A faint heritability was calculated from the regression of $F_3$ lines grown at Suwon on the $F_2$ individuals grown at IRRI for most combinations, especially in the combinations involving shortday sensitive varieties. This implies low efficiency for the selection of heading days of $F_2$ individuals at IRRI to be grown in lines at Suwon. 7. No significant reciprocal effects were measured for $F_1$ and $F_2$ mean heading days. 8. Partitioning the observed photoperiod sensitivity. into two components, parental array mean md the deviation from this array mean, the parental photoperiod sensitivity contributing to the hybrids was measured in terms of general and specific combining ability for photoperiod sensitivity. 9. The photoperiod sensitivity of $F_1$s was higher than that of the parents, and it decreased as the generation progressed in most combinations of tested varieties. 10. The response of heading days to difference of temperature was weaker for $F_1$ hybrids than for the parents. The differences of temperature responses between the longday and shortday treatments were specific for the variety. 2. Sterility : 1. The $F_1$ sterility was specific for the combinations and not correlated to the parental sterility. The sterility of $F_1$s grown under the 10 hours condition was higher than of those grown under 14 hours. These results were the same at both locations, IRRI and Suwon. 2. The high sterile combinations in $F_1$ showed high sterility in $F_2$. The combinations between a high photoperiod sensitive variety and a high temperature sensitive variety showed high sterility and wider variance. 3. The mean sterility of $F_2$s was lower than of $F_1$s and the mean of $F_3$ lines was lower than of $F_2$s. Sterility decreased as the generation progressed, and the differences of $F_3$ sterility of different combinations were not significant. 4. A faint correlation between grain sterility and pollen sterility was observed in $F_2$ populations. 5. No significant reciprocal effects were measured in $F_1$ and $F_2$ sterility. 6. Following Griffing's method, specific combining ability effects were higher than general combining ability effects, especially in the combinations between highly photoperiod sensitive varieties and highly temperature sensitive varieties. 7. No distinct correlations were found between $F_2$ individual sterility grown at IRRI and $F_3$ line sterility grown at Suwon. 8. No distinct correlations were observed between heading days and sterility of $F_2$ individuals.

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