• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.27 no.5
• /
• pp.385-396
• /
• 2001

The purpose of this experiment was to examine the histological changes and the pattern of expression of proliferating cell nuclear antigen(PCNA) and type I collagen in the elongated bone affected by osteodistraction of the mandibular body in an adult canine model. Seven adult male mongrel dogs weighing over 20kg were used for this experiment. The author excluded 3 animals because they died before the planned time of sacrifice. The custom-made linear extraoral device and 4 bicortical fixation screws 2.3mm in diameter, 50mm in total length, 15mm in screw length were used in each animal. The distal part of the distractor produced a 0.75mm gap between proximal and distal bony segments every $360^{\circ}$ turn of the rotation rod of the device. The mandibular body of the right side from each animal was experimental side and the left side was left intact and served as control. At the experimental side, the mandibular body was osteotomized. After 5-day latency period, the segments were distracted with a rate of 1.1mm/day and a rhythm of two/day for ensuing 7 days. The animals were sacrificed at the 4th. 17th, and 32th day after the end of the distraction. The bony specimens were decalcified, embedded in paraffin, sectioned $5{\mu}m$ thick and stained with Masson trichrome and examined under the light microscope. The immunohistochemical examinations using anti-PCNA antibody and anti-type-I collagen antibody were performed to examine the pattern of the expression of PCNA and type I collagen, respectively. Results : 1. The mean increment of the distance between the proximal and distal screw-holding parts of the distractor was 6.8mm. The average elongation of the mandible in the experimental side was 5.3mm. The loss of elongation was 1.5mm in average. 2. New bone was already observed at the 4th. day after the end of distraction. But, bony union was not completed in the distraction gap at the 32th. day after the end of distraction by radiographic and microscopic examinations. 3. The expression rate of PCNA positive cells in the distraction gap had a tendency of decrease from 35.1-68.8% initially, to 49.1%, and finally to 17.6-27.2%. But at the final period, the tissue of the elongated gap still had the ability of cell proliferation. On the other hand, the expression of PCNA positive cells in the control side were negligible through the experimental period. 4. PCNA positive cells were observed primarily both at the central fibrous zone and at the region of just adjacent to CFZ which initiated new bone formation. 5. The expression pattern of the type I collagen was not zone-specific. They were observed diffusely throughout the elongation gap. 6. The predominant mechanism of new bone formation in the distraction gap was intramembranous. But, some of the regenerated bone was formed by endochondral ossification.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.31 no.2
• /
• pp.169-179
• /
• 2004

The purpose of this study was to discriminate clinically and radiographically among the three groups of dentigerous cysts studied. First, Group I, involved area of dentigerous cyst was successive permanent tooth area beneath deciduous tooth. Second, Group II, involved permanent molar area, and the last, Group III involved maxillary anterior supernumerary tooth area. The author observed and compared the clinico-radiographic features of 49 cases of Group I, 36 cases of Group II, and 15 cases of Group III of dentigerous cyst and this observation and comparison had been done by based on the charts and panoramic films. The obtained results were as follows: 1. The cases of Group I were 29 cases and, those of Group II were 36 and those of Group III were 15. 2. The incidence of dentigerous cyst is high in first decade. In Group I, before first decade and early first decade was 87.8%, in Group II and Group III, was discovered more lately. 3. The frequency of dentigerous cyst is 2.5 times higher in male than in female. 4. The sequence of chief complaint was swelling(50%), routine examination(32%), and pain(9%). 5. When considering the type of the cyst, lateral type is many most in Group I (71.4%) and central type is many most in Group II (94.4%) and Group III (100%). 6. The most size of dentigerous cyst was 2 crown size in Group I, 1 crown size in Group II, above of 4 crown size in Group III. 7. Almost involved teeth showed displacement and some tooth of displaced teeth showed delayed root development and dilaceration of root. 8. The most many response of alveolar bone was buccal bone expansion in Group I (67.3%), no bone expansion in Group II(66.7%) and palatal bone expansion in Group III (60.0%). 9. The percentage of involved teeth were as follows : The mandibular third molar was 31% and many most. The mandibular second premolar was 30%. Mesiodens of maxillary anterior area was 15%. The maxillary canine was 8%. The mandibular first premolar was 5%. 10. In the Group I, causes suggesting of dentigeous cyst are pulpotomized deciduous tooth(59.2%), severe dental caries of deciduous tooth, untreated traumatic history on the deciduous tooth etc. 11. The treatment method of dentigerous was marsupialization in 61.2% of cases of Group I and that was enucleation in 61.1% of cases of Group II and in 80.0% of cases of Group III.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.38 no.1
• /
• pp.10-20
• /
• 2020

This study aims to analyze the developed characteristics of the knowledge and information of gardens through garden or flowering plant books compiled in the 15th and 19th centuries of Joseon Dynasty. Diachronically analysis of the garden or flowering plant books classified the characteristics in which knowledge and information about gardens are developed by the period, and looked at the factors. The results are as follows; First, the relationship between the authors who compiled the garden or flowering plant books had similar characteristics to the genealogy of Realist School of Confucianism(實學) in the Joseon Dynasty. Kang, Hee-An's practical features influenced later realist school of confucianism scholars. Lee, Su-Gwang has accumulated knowledge of the garden through his experience of traveling the diplomatic envoy to China. Since then, Hong Man-sun's ideology has been related to Charles, a member of the Southerners. Seo Yu-gu was also able to accept Realist School of Confucianism in an integrated way through the Jungnong school's theory and interaction with the Jungsang school. Ryu, Jung-Lim's relationship with the Jungnong school emerged as he added to the 『Jeungbosanrimgyeongje(增補山林經濟)』. Second, the 『Yanghwasorok(養花小錄)』, 『Jibongyuseol(芝峯類說)』 「Hwuimok(卉木)」, 『Hangjeongrok(閑情錄)』, 『Sanrimgyeongje(山林經濟)』 「Yanghwa(養花)」, 『Jeungbosanrimgyeongje(增補山林經濟)』 「Yanghwa(養花)」, 『Hwaamsurok(花庵隨錄)』 and 『Imwongyeongjeji(林園經濟志)』 「Yewonji(藝畹志)」 contain garden plant characteristics, cultivation methods, and management methods. The 『Imwongyeongjeji(林園經濟志)』 「Seomyongji(贍用志)」, 「Iunji(怡雲志)」, 「Sangtaekji(相宅志)」 contain details on the location selection of gardens, the layout of facilities, how to create them and materials. The description of these garden or flowering plant books was found to be the most common introduction with 55 percent, followed by methodologies(42.8%), the Lichi Theory(理氣論, 15.5%), the classification(12.4%), and the convention(1.9%). Third, based on the importance of knowledge and information on gardens, the garden or flowering plant books related to the period were classified as early period, including 『Yanghwasorok(養花小錄)』, 『Jibongyuseol(芝峯類說)』 which were compiled before the 17th century. The 18th-century compiled 『Sanrimgyeongje(山林經濟)』 and 『Jeungbosanrimgyeongje(增補山林經濟)』 were classified as middle period, and the 19th-century compilation of 『Imwongyeongjeji(林園經濟志)』 was classified as late period. The garden or flowering plant books were cited the contents of ancient Chinese books, the author's experiences and opinions contained in the preceding period in later garden books. And the reinforcement of garden knowledge was made to reflect the agricultural technology and expertise developed at the time of writing. Fourth, based on analysis of the development and acceptance of knowledge information in garden by period, In the early period was dealing with floriculture as a way to explore the logic of things. Later, in the 18th century, a vast influx of garden knowledge information came from China. Among scholars, they secured justification for garden creation as part of various knowledge-seeking activities, which expanded their expertise in gardens. In response to the trend of gardening in the 19th century, professional books were written based on knowledge and information on gardens that were collected in the past, and systems were established such as the collection and management of garden plants, construction methods, enjoying methods, and self-realization.

• Korean journal of communication and information
• /
• v.33
• /
• pp.115-167
• /
• 2006

The purpose of this study was to investigate coverage patterns of the Korean internet news media on 'US-Iraq War' and its meaning and discourse structure. The internet news media was recently established and become a popular news media to compete with old news media in Korea. The author selected the 'Oh My News' as a representative internet news media for his analysis, and collected its news items from Mar. 20, 2003 to Dec. 17, 2003. on the basis of 4 different phases of the war. He analysed the whole of news items with various semiotic and discourse analytic methods, especially applying for Bell's concepts of time and discourse structure. As a result of this study, first of all, it was found that the 'Oh My News' tended to cover this war so different ways as the old news media did. It did not pay attention to the procedure of war, especially, battlefields, fighting between US and Iraq, damages and casualties. But, instead, it paid attention to many doubts about intention of US government and the President, Bush, dichotomous shift between pro-America and anti-America, rightness of dispatching Korean army into Iraq, etc. Secondly, it functioned as a kind of alternative media to speak up different voices comparing with those of old media. It tended to suggest different perspectives and opinions, while the old media tended to follow American perspectives and opinions. Thirdly, it became as a kind of new media setting agendas for this war in Korean society. It played a very important role for setting agendas for various issues related with this war. In conclusion, the internet news media has recently become a kind of new news media for suggesting alternative or different opinions, setting agendas, initiating discourses, etc., even though it still has may problems of becoming so called orthodox news media.

• Korean Journal of Psychosomatic Medicine
• /
• v.8 no.1
• /
• pp.88-97
• /
• 2000

Objectives : This study was aimed to investigate the emotional state and personality factors of patients with vitiligo, and the impacts of clinical characteristics. Methods : Twenty one patients with vitiligo and 20 normal controls were studied. Beck Depression Inventory(BDI), Spielberg's State and Trait Anxiety Inventory(STAI) and Cattell's 16 Personality Factors Questionnaire(16-PF) were used for assessment. Statistically, t-test, Oneway ANOVA, Mann-Whitney U test and Pearson's correlation test were used. Results : The Results were as follows. 1) The comparison of total score of BDI, state anxiety and trait anxiety between the patients with vitiligo and normal controls were not significantly different. 2) In first-stratum source traits of 16-PF, normal control group was significantly higher than the patients with vitiligo in H-factor(Boldness) and I-factor(Tender-mindedness). In second-stratum source traits of 16-PF, there was no significant difference between the patients with vitiligo and normal control in all factors. 3) According to sex, the comparison of total scores of BDI, STAI between male and female patients with vitiligo were not significantly different. In the comparison of 16-PF, female patients were higher than male patients in I-factor only. 4) As according to age(under and over 30 years of age), the comparison of total scores of BDI, STAI between patients over 30 years of age and under 30 years of age were not significantly different. In the comparison of 16-PF, patients over 30 years of age were higher than patients under 30 years of age in E-, G-, L-, M-, Q2-, Q3-, IND-, SUP-, and CRE-factor. 5) As according to the presence of progression of vitiligo and the presence of visible lesion, the comparison of total scores of BDI, STAI and 16-PF were not significantly different. 6) There were no significant correlation between the duration of the vitiligo and BDI, STAI-S, STAI-T, and 16-PF. Conclusions : There were no significant difference between patients with vitiligo and normal controls on the emotional state and personality characteristics. But patients with vitiligo were more bolder and tender-minded than normal controls on 16-PF. The author propose that methods of treatment to resolve problems of the interpersonal relations will be helpful.

• Journal of Plant Biology
• /
• v.15 no.s
• /
• pp.1-32
• /
• 1972

In order to utilize for the prevention and preservation of the Han River from the environmental pollution the present studies were carried out to clarify the microflora and estimation of the water pollution levels of the Han River. In addition to the above regional and seasonal fluctuation of the phytoplankton was also examined. Samples of phytoplankton were collected from 6 stations in the South Han River during the period from December, 1971 to October, 1972. The results obtained during the present studies are as follows: 1. The phytoplankton samples collected from 6 stations, Yeoju, Hajapo-ri, Yangpyeong, Daruraegi, Giduwon and Paldang were identified and classified by Engler's classification system(1954). It resulted in 2 phylum, 2 classes, 7 orders, 10 families, 29 genera, 137 species, 1 sub-species, 49 varieties, 6 forma and 2 variety-forma. The total numbers of phytoplankton identified were 195 species, of which 7 families, 27 species, 26 varieties, 4 forma and 2 variety-forma are new to Korea, that of 54 species are first described in Korea. 2. In lower area of the Han River it is found 53 species from Paldang and in middle area it is found 114 species from Giduwon, 95 species from Daruraegi, 66 species from Yangpyeong, 71 species from Hajapori and 81 species from Yeoju. In standpoint of seasonal fluctuation of phytoplankton, the total numbers of the plankton is more abundant in summer than in winter season and it shows bimodal pattern. 3. As compared with previous data which obtained from 30 stations covering estuary to upper area, both South and North Han River, during the period from 1965-1972 it is shown that 10 species of the South Han River and 11 species of the North Han River are found throughout all seasons. Among the above species two are common in both area. In the other hand it is found that 9 species in spring season and 6 species in fall season in the South Han River and 10 species in spring, 23 species in summer, 4 species in fall and 15 species in winter season in the North Han River shows their seasonal fluctuation in this area. Among the seasonal occurrence of phytoplankton 10 species were consider to be indicator for the estimation of biological water pollution levels. 4. According to Fjerdingstad's water pollution level system (1963) the total numbers of 1, 230 species which have been collected from the Han River since 1965 includes 27 species of phytoplankton as indicator; 3 species of blue-green algae, 20 species of diatom, and 4 species of green-algae. 5. With 27 indicator species new estimation of water pollution level system was arranged for water pollution in the Han River. 6. The lower part of the central area of the Han River indicates mesosaprobic. In central area of the Han River shows mesosaprobic and oligosaprobic, but predominant in mesosaporobic. And it is indicated that mesosaprobic, oligosaprobic, and polysaprobic factors mixed up in the North Han River. Compare with their water pollution level in the South and North Han River, with author's new system, it is estimated that North Han River is more polluted than South Han River. 7. The reason why North Han River is more polluted suggested that the selfpurification action was limited by their circulation speed. The rapid speed of water in the North Han River is mainly caused by their topography and water-drainage from waterpower plant. In conclusion the central area of the Han River consist of mesosaprobe zone, as a part with oligosaprobe zone. But the presence of polysaprobe zone in the North Han River gives us many problems in future for the nationa development programme and natural conservation in this area.

• Korean Journal of Plant Taxonomy
• /
• v.41 no.2
• /
• pp.144-155
• /
• 2011

The infraspecific taxa of Adonis amurensis Regel et Radde are currently known to include one subspecies (subsp. nanus Y. Lee), two varieties (var. ramosa Makino, and var. dissectipetalis Y. Lee) and two forms (for. argentatus Y. Lee, and for. viridescensicalyx Y. Lee). Among them, the remaining three taxa except for subsp. nanus and var. dissectipetalis are unified with A. amurensis. Therefore, we examined the morphological characteristics and geographical distribution of A. amurensis in effort to elucidate the taxonomic status of subsp. nanus and var. dissectipetalis. After the subsp. nanus samples had been transplanted from their type locality, i.e. highland at more than 1,000 m above sea level, to a lowland habitat, we measured the samples' morphological characteristics. The range of values we recorded of the plant height and floral diameter from the subsp. nanus samples were within the parameters used to characterize A. amurensis. Accordingly, subsp. nanus has been characterized as an ecophene of A. amurensis. It is considered as a synonym of A. amurensis. Among the populations of A. amurensis (sensu Y.Lee, author), those with highly dissected petals at their apices have previously been described as var. dissectipetalis. However, this characteristic has been observed together with obtuse or rounded petal apices not only in one population but also in a single individual. However, populations with these characteristics belong to A. pseudoamurensis due to the simultaneous development of leaves and flowers, branched stems, acute leaf apices, and petals that are shorter than sepals. Therefore, we suggest that A. amurensis var. dissectipetalis be unified with A. pseudoamurensis. Very useful characteristics for distinguishing A. amurensis from its relative species are anthesis, the presence or absence of branches, the development of scales into normal leaves, the relative length of the sepals and petals, and the position of the stipules. A. amurensis is geographically restricted to E. Asia, including E. Siberia, and especially on the Korean Peninsula, it is distributed throughout the northern provinces of Gyeonggi province and in Gangwon province, Gyeongbuk province (Mt. Bohyeon-san) and Jeonbuk province (Mt Jeoksang-san) along Baekdudaegan mountain.

• Korean Journal of Agricultural Science
• /
• v.7 no.2
• /
• pp.131-144
• /
• 1980

The Linear Regression Model to extend the monthly runoff data in the short-recorded river was proposed by the author in 1979. Here in this study generalization precedure is made to apply that model to any given river basin and to any given station. Lengthier monthly runoff data generated by this generalized model would be useful for water resources assessment and waterworks planning. The results are as follows. 1. This Linear Regression Model which is a transformed water-balance equation attempts to represent the physical properties of the parameters and the time and space varient system in catchment response lumpedly, qualitatively and deductively through the regression coefficients as component grey box, whereas deterministic model deals the foregoings distributedly, quantitatively and inductively through all the integrated processes in the catchment response. This Linear Regression Model would be termed "Statistically deterministic model". 2. Linear regression equations are obtained at four hydrostation in Geum-river basin. Significance test of equations is carried out according to the statistical criterion and shows "Highly" It is recognized th at the regression coefficients of each parameter vary regularly with catchment area increase. Those are: The larger the catchment area, the bigger the loss of precipitation due to interception and detention storage in crease. The larger the catchment area, the bigger the release of baseflow due to catchment slope decrease and storage capacity increase. The larger the catchment area, the bigger the loss of evapotranspiration due to more naked coverage and soil properties. These facts coincide well with hydrological commonsenses. 3. Generalized diagram of regression coefficients is made to follow those commonsenses. By this diagram, Linear Regression Model would be set up for a given river basin and for a given station (Fig.10).

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.10 no.1
• /
• pp.367-382
• /
• 1997

The author analyzed 46 cases of allergic rhinitis patients, who were treated in the Kwang-ju Oriental Medical Hospital of Wonkwang University from January 1997 to April 1996. I've examined the 46 cases in the view of age and sex distribution, seasonal distribution, distribution of the job, duration of the disease, past history, family history, distribution of complicated signs, the degree of recovery about the total patient, the relationship of the ages and the remedial value, the relationship of the duration of disease and the remedial value. The following results are obtained. 1. The ratio of under teenagers was $32.61\%$(15 cases), teenagers was $30.43\%$(11 cases), 2th decade was $17.39\%$(8 cases), 3th decade was $17.39\%$(8 cases), 4th decade was $4.35\%$(2 cases), 5th decade was $2.17\%$(1 case), over sixty was $2.17\%$(1 case). 2. The ratio of the male was $58.70\%$(27 cases) and femal was $41.30\%$(19 cases). 3. The ratio of spring was $21.74\%$(10 cases), summer was $8.70\%$(4 cases), fall was $43.48\%$(20 cases), winter was $43.48\%$(20 cases) and unknown was $10.87\%$(5 cases). 4. The ratio of the students was $45.65\%$(21 cases), house-wives was $15.22\%$(7 cases), office men was $10.87\%$(5 cases), farmers was $4.35\%$(2 cases), driver was $2.17\%$(1 case) and unemployed was $21.74\%$(10 cases). 5. The ratio of the under six months was $8.70\%$(4 cases), under 1 year was $17.39\%$(8 cases), under 3 years was $32.60\%$(15 cases), over 3 years was $41.31\%$(19 cases). 6. The ratio of atopic dermatitis was $32.61\%$(15 cases), allergic dermatitis was $21,74\%$(10 cases), the asthma was $17.39\%$(8 cases), digestion disorder was $6.52\%$(3 cases) and etc. 7. The ratio of paternal line was $21.74\%$(10 cases), maternal line was $13.04\%$(6 cases), paternal and maternal lines was $4.35\%$(2 cases), brother or sisters was $13.04\%$(6 cases) and non-significant was $47.83\%$(22 cases). 8. The ratio of sneezing was $100\%$(46 cases) , nasal discharge was $100\%$(46 cases), nasal obstruction was $86.96\%$(40 cases), pruritus was $45.65\%$(21 cases), headache was $13.04\%$(6 cases), asthma was $10.87\%$(5 cases), digestion disorder was $6.52\%$(3 cases), light phovia was $6.52\%$(3 cases), tears was $4.35\%$(2 cases), nosebreeding was $2.17\%$(1 case). 9. The total remedial value of the 46 patients was revealed $52.17\%$. 10. The remedial value of under teenagers, teenagers were higher than the total remedial value($52.17\%$). 11. The remedial value of under 6 months, under 1 year were higher than the total remedial value($52.17\%$). These results demonstrated that in the point of remedial view, the patients who were younger and shorter of the duration of disease, would be well recovered.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.10 no.1
• /
• pp.383-402
• /
• 1997

The author analyzed 155 cases of Facial Palsy, excluding lesions caused by cerebrovascular attacks, who were treated in the Kwang-ju Oriental Medical Hospital of Wonkwang University from March 1996 to September 1996. I've examined the 155 cases in the view of the etiologic distributions, the age, the relationship of the sex and paralytic side, attended symptoms and analyzed 95 cases who were treated over ten times in the view of the ratio of recovery according to the age, anatomic focus, the relations of sex and paralytic side. The following results are obtained. 1. The ratio of punghan(風寒) was $20.64\%$(32 cases), overwork was $18.70\%$(29 cases), stress was $6.44\%$(10 cases), excessive drinking was $3.23\%$(5 cases), teeth pain was $1.93\%$(3 cases), and idiopathy was $38.05\%$(59) and etc. 2. The ratio of stylomastoid pain was $15.48\%$(24 cases), auricular pain was $10.32\%$(16 cases), headache was $4.51\%$(7 cases), eyedried was $4.51\%$(7 cases), taste paralysis was $2.57\%$(4 cases), tinnitus was $2.57\%$(4 cases) and non-significant symptoms was $50.97\%$(79) and etc. 3. The ratio of 2th and 5th decade were $20.00\%$(31 cases), 4th decade was $18.71\%$(29 cases), 3th decade was $16.71\%$(26 cases), 6th decade was $11.61\%$(18 cases), teenagers in $5.81\%$(9 cases), over seventy and under teenagers were $3.23\%$(5 cases), and infant was $0.65\%$(1 case). 4. The ratio of the male-right was $28.39\%$(44 cases), female-right was $25.82\%$(40 cases), male-left was $23.23\%$(36 cases), female-left was $20.65\%$(32 cases) and male-both side was $1.94\%$(3 cases) in order. 5. Topographically, The ratio of the infrachordal lesion was $72.90\%$(113 cases), transgeniculate lesion was $16.13\%$(25 cases), suprageniculate lesion was $5.81\%$(9 cases), infrastapedial lesion was $3.87\%$(6 cases) and suprastapedial lesion was $1.29\%$(2 cases) in order. 6. When we examined the degree of recovery about the 95 patients who were treated over ten times after on attack, normal improvement was seen in $46.32\%$(44 cases), excellent in $7.37\%$(7 cases), good in $12.63\%$(12 cases), fair in $13.68\%$(13 cases), poor in $20.00\%$(19 cases). The total remedial value of the 95 patients who were treated over ten times was revealed $61.58\%$. 7. When we examined the 95 patients who were treated over ten times, the remedial value of the infant was $50.00\%$, under teenagers $43.75\%$, teenagers $37.50\%$, 2th decade $56.82\%$, 3th decade $64.06\%$, 4th decade $55.00\%$, 5th decade $73.53\%$, 6th decade $77.50\%$, over seventieth $68.75\%$. The remedial value of 3th decade, 5th decade, 6th decade, 7th decade and over seventieth were higher than the total remedial value($61.58\%$) 8. In the point of topographical lesion, when we examined the 95 patients who were treated over ten times, the remedial value of infrachordal lesion was $66.78\%$, infrastapedial lesion $58.33\%$, suprastapedial lesion $50.00\%$, transgeniculate lesion $48.44\%$, suprageniculate lesion $31.25\%$, in order. Only the remedial value of Infrachordal($66.78\%$) was higher than the total remedial value($61.58\%$). 9. In the point of the relationship of the sex and the paralytic side, when we examined the 95 patients who were treated over ten times, the remedial value of male-left was $57.29\%$, male-right $61.54\%$, male-both side $58.33\$%, female-left $57.81\%$ and female-right $68.27\%$. Only the remedial value of female-right($68.27\%$) was higher than the total remedial value($61.58\%$). These results demonstrated that in the point of prognostic view there was more concerned with the topographical lesion, body condition than the traditional rule of sex-paralytic relationship that man is awed left paralysis and woman right paralysis.