• Korean Journal of Remote Sensing
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• v.38 no.2
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• pp.215-222
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• 2022

In this study, the effect of wavelength range and absorption cross-section used to retrieve nitrogen dioxide (NO₂) vertical column density (VCD) from Pandora was analyzed using Differential Optical Absorption Spectroscopy (DOAS). During the GEMS Map of the Air Pollution (GMAP) 2020 campaign, data from direct sunlight observation with Pandora instrument in Seosan was used, and NO₂ VCD was retrieved under four conditions. The average NO₂ VCD under the four conditions ranged from 1.22×10¹⁶~1.38×10¹⁶ molec. cm^-2, with a maximum difference of 0.16×10¹⁶ molec. cm^-2 between each condition. The fitting error averaged 3.19~9.59%, showing an error within 10% in all cases, and the RMS was 5.11×10^-3~7.16×10^-3 molec. cm^-2. The retrieved NO₂ VCD using 4 conditions shows a slope in the range of 0.98 to 1.09 and correlation of 0.96 to 0.98 in comparison with Pandonia Global Network (PGN).

• Journal of Korean Philosophical Society
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• v.119
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• pp.141-172
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• 2011

This thesis, centered on J. Locke and W. v. Humboldt's concept of language, is written for the purpose of illuminating their view of language and investigating the relationship between a matter of language and that of thought. First, Locke considers language was to be the great instrument and common tie of society. And language consists of words, and words are signs of ideas. Locke's discussion in language is shaped by his belief that these conditions of the transference of knowledge were in his time commonly unsatisfied, especially in two domains. First, there was no agreed classification of 'substance' based on careful observation and experiment. Second, the ideas associated with the names of mixed modes often varied both in the usage of different people and in that of the same person at different times. But Humboldt deals with 'the diversity of the structure of human language' and deals with it in respect of 'its influence on the spiritual development of mankind.' According to his theory, a language is not work(ergon) but an activity(energeia). Its true definition may therefore only be genetic. It is after all the continual intellectual effort to make the articulated sound capable of expressing thought. In short, he conceives of language as a particular 'intellectual effort'.

• Journal of the Korean earth science society
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• v.39 no.2
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• pp.119-130
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• 2018

Aerosol Optical Properties (AOPs) are retrieved using the geostationary satellite instruments such as Geostationary Ocean Color Imager (GOCI), Meteorological Imager (MI), and Advanced Himawari Imager (AHI) through Yonsei AErosol Retrieval algorithm (YAER). In this study, the retrieved aerosol optical depths (AOD)s from each instrument were intercompared and validated with the ground-based sunphotometer AErosol Robotic NETwork (AERONET) data. As a result, the four AOD products derived from different instruments showed consistent results over land and ocean. However, AODs from MI and GOCI tend to be overestimated due to cloud contamination. According to the comparison results with AERONET, the percentage within expected errors (EE) are 36.3, 48.4, 56.6, and 68.2% for MI, GOCI, AHI-minimum reflectivity method (MRM), and AHI-estimated surface reflectance from shortwave Infrared (ESR) product, respectively. Since MI AOD is retrieved from a single visible channel, and adopts only one aerosol type by season, EE is relatively lower than other products. On the other hand, the AHI ESR is more accurate than the minimum reflectance method as used by GOCI, MI, and AHI MRM method in May and June when the vegetation is relatively abundant. These results are explained by the RMSE and the EE for each AERONET site. The ESR method result show to be better than the other satellite product in terms of EE for 15 out of 22 sites used for validation, and they are better than the other product for 13 sites in terms of RMSE. In addition, the error in observation time in each product is found by using characteristics of geostationary satellites. The absolute median biases at 00 to 06 Universal Time Coordinated (UTC) are 0.05, 0.09, 0.18, 0.18, 0.14, 0.09, and 0.10. The absolute median bias by observation time has appeared in MI and the only 00 UTC appeared in GOCI.

• Journal of the Korean Chemical Society
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• v.64 no.2
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• pp.67-73
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• 2020

The study aimed to investigate in vitro lipid deposition of oleic acid, oleic acid methyl ester and cholesterol on a daily disposable (1-day lenses) and 3-days lenses over 3 days and changes of optical characteristics is also investigated. Artificial tear solutions were prepared to simulate actual tear compositions. Two types of contact lenses (1-day lenses (Senofilcon A) and 3-days lenses (silicone tripolymer)) were soaked in the artificial tear solutions within an incubator at 37 ℃ with 150 rpm for 8, 16, 24 hours. Lipid deposition (oleic acid, oleic acid methyl ester and cholesterol) were measured using high performance liquid chromatography (HPLC) instrument. In addition, measurements of oxygen transmissibility, light transmittance and observation of lens surface were conducted. The amount of lipid deposition on the 1-day lenses were 127.55 ㎍/lens for Day 1, 302.96 ㎍/lens, for Day 2, and 353.30 ㎍/lens for Day 3. The 3-days lenses were 46.22 ㎍/lens for Day 1, 66.07 ㎍/lens for Day 2, and 67.45 ㎍/lens for Day 3. Oxygen transmissibility were 81×10^-9(cm/sec)(ml O₂/ml×mmHg)(Baseline) and 48×10^-9(cm/sec)(ml O₂/ml×mmHg) (Day 3) for the 1-day lenses, it were 13.23×10^-9(cm/sec)(ml O₂/ml×mmHg)(Baseline) and 9.6×10^-9(cm/sec)(ml O₂/ml×mmHg) (Day 3) for the 3-days lenses. Transmittance of each lenses were 97.21% (Baseline) and 94.25% (Day 3) for the 1-day lenses, 97.65% (Baseline) and 95.15% (Day 3) for the 3-days lenses. Observation of surface deposition indicated greatest deposition for the 3-days lenses type on Day 3. Lipid deposition for both lens types increased by day and was greater for the 1-day lenses type. Surface deposition appeared to differ as it was greatest for the 3 days lens type, which may suggest other deposits such as protein may be present.

• Hwankyungkyoyuk
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• v.7 no.1
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• pp.1-17
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• 1994

This study was performed to determine appropriate teaching-learning and evaluation methods for Environmental Studies. To promote the relevance of our study to the needs of the schools and concerned educational communities of environmental education, we reviewed related literature, conducted questionnaire surveys, interviewed related teachers and administrator, held meetings with experts, and field-tested our findings. For selecting and developing teaching-learning methods of Environmental Studies, findings of educational research in general are considered. moreover, principles of environmental education, general aim of environmental education, orientations of environmental education, and developmental stages of middle school students in educational psychology were attended. In addition, relevance to the purpose of the Environmental Studies curriculum, appropriateness for value inquiry as well as knowledge inquiry, small group centered class organization, social interaction centered teaching-learning process, regional environmental situation, significance of personal environment, evaluation methods of Environmental Studies, multi- and inter-disciplinary contents of the Environmental Studies textbook, suitability to the evaluation methods of Environmental Studies, and emphasis on the social interaction in teaching-learning process were regarded. It was learned the Environmental Studies can be taught most effectively in via of holding discussion sessions, conducting actual investigation, doing experiment-practice, doing games and plate, role-playing and carrying out simulation activities, and doing inquiry. These teaching-learning methods were field-tested and proved appropriate methods for the subject. For selecting and developing evaluation method of Environmental Studies, such principles and characteristics of Environmental Studies as objective domains stated in the Environmental Studies curriculum, diversity of teaching-learning organization, were appreciated. We categorized nine evaluation methods: the teacher may conduct questionnaire surveys, testings, interviews, non-participatory observations; they may evaluate student's experiment-practice performances, reports preparation ability, ability to establish a research project, the teacher may ask the students to conduct a self-evaluation, or reciprocal evaluation. To maximize the effect of these methods, we further developed an application system. It considered three variables, that is, evaluates, evaluation objectives domains, and evaluation agent, and showed how to choose the most appropriate methods and, when necessary, how to combine uses of different methods depending on these variables. A sample evaluation instrument made on the basis of this application system was developed and tested in the classes. The system proved effective. Pilot applications of the teaching-learning methods and evaluation method were made simultaneously; and the results and their implications are as follows. Discussion program was applied in a lesson dealing with the problems of waste disposal, in which students showed active participation and creative thinking. The evaluation method used in this lesson was a multiple-choice written test for knowledge and skills. It was shown that this evaluation method and device are effective in helping students' revision of the lesson and in stimulating their creative interpretations and responces. Pupils showed great interests in the actual investigation program, and this programme was proved to be effective in enhancing students' participation. However, it was also turned out that there must be pre-arranged plans for the objects, contents and procedures of survey if this program is to effective. In this lesson, non-participatory observation methods were used with a focus on the attitudes of students. A scaled reported in general description rather than in grade. Experiment-practice programme was adopted in a lesson for purifying contaminated water and in this lesson, instruction objectives were properly established, the teaching-learning process was clearly specified and students were highly motivated. On the other hand, however, it was difficult to control the class when some groups of students require more times to complete their experiment, and sometimes different results. As regards to evaluation, performance observation test were used for assessing skills and attitudes. If teachers use well-prepared Likert scale, evaluation of all groups within a reasonablely short period of time will be possible. The most effective and successful programme in therms of students' participation and enjoyment, was the 'ah-nah-bah-dah-market' program, which is kind of game of the flea market. For better organized program of this kind, however, are essential, In this program, students appraise their own attitudes and behavior by responding to a written questionnaire. In addition, students were asked to record any anecdotes relating to self-appraisal of changes on one's own attitudes and behaviours. Even after the lesson, students keep recording those changes on letters to herself. Role-playing and simulation game programme was applied to a case of 'NIMBY', in which students should decide where to located a refuse dumping ground. For this kind of programme to e successful, concepts and words used in the script should be appropriate for students' intellectual levels, and students should by adequately introduced into the objective and the procedures of the lessons. Written questionnaire was used to assess individual students' attitudes after the lesson, but in order to acquire information on the changes of students' attitudes and skills, pre-test may have to be made. Doing inquiry programme, in which advantages in which students actually investigated the environmental influence of the areas where school os located, had advantages in developing students' ability to study the environmental problems and to present the results of their studies. For this programme to be more efficient, areas of investigation should be clearly divided and alloted to each group so that repetition or overlap in areas of study and presentation be avoided, and complementary wok between groups bee enhanced. In this programme, teacher assessed students' knowledge and attitudes on the basis of reports prepared by each group. However, there were found some difficults in assessing students' attitudes and behaviours solely on the grounds of written report. Perhaps, using a scaled checklist assessing students' attitudes while their presentation could help to relieve the difficulties.

• Korean Journal of School Psychology
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• v.16 no.3
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• pp.433-451
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• 2019

This study aimed to develop and validate the Classroom Problem Behavior Scale - Elementary School Version (CPBS-E) measure which is unique to classroom problem behavior exhibited by Korean elementary school students. The focus was on developing a universal screening instrument designed to identify and provide intervention to students who are at-risk for severe social-emotional and behavioral problems. Items were initially drawn from the literature, interviews with elementary school teachers, common office discipline referral measures used in U.S. elementary schools, penalty point systems used in Korean schools, 'Green Mileage', and the Inventory of Emotional and Behavioral Traits. The content validity of the initially developed items was assessed by six classroom and subject teachers, which resulted in the development of a preliminary scale consisting of 63 two-dimensional items (i.e., Within Classroom Problem Behavior and Outside of Classroom Problem Behavior), each of which consisted of 3 to 4 factors. The Within Classroom Problem Behavior dimension consisted of 4 subscales (not being prepared for class, class disruption, aggression, and withdrawn) and the Outside of Classroom Problem Behavior dimension consisted of 3 subscales (rule-violation, aggression, and withdrawn). The CPBS-E was pilot tested on a sample of 154 elementary school students, which resulted in reducing the scale to 23 items. Following the scale revision, the CPBS-E was validated on a sample population of 209 elementary school students. The validation results indicated that the two-dimensional CPBS-E scale of classroom problem behavior was a reliable and valid measure. The test-retest reliability was stable at above .80 in most of the subscales. The CPBS-E measure demonstrated high internal consistency of .76-.94. In examining the criterion validity, the scale's correlation with the Teacher Observation of Classroom Adaptation-Checklist (TOCA-C) was high and the aggression and withdrawn subscales of the CPBS-E demonstrated high correlations with externalization and internalization, respectively, of the Child Behavior Checklist - Teacher Report Form CBCL-TRF). In addition, the factor structure of the CPBS-E scale was examined using the structural equation model and found to be acceptable. The results are discussed in relation to implications, contributions to the field, and limitations.

• Journal of Global Scholars of Marketing Science
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• v.18 no.3
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• pp.59-88
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• 2008

Digital Convergence means integration between industry, technology, and contents, and in marketing, it usually comes with creation of new types of product and service under the base of digital technology as digitalization progress in electro-communication industries including telecommunication, home appliance, and computer industries. One can see digital convergence not only in instruments such as PC, AV appliances, cellular phone, but also in contents, network, service that are required in production, modification, distribution, re-production of information. Convergence in contents started around 1990. Convergence in network and service begins as broadcasting and telecommunication integrates and DMB(digital multimedia broadcasting), born in May, 2005 is the symbolic icon in this trend. There are some positive and negative expectations about DMB. The reason why two opposite expectations exist is that DMB does not come out from customer's need but from technology development. Therefore, customers might have hard time to interpret the real meaning of DMB. Time is quite critical to a high tech product, like DMB because another product with same function from different technology can replace the existing product within short period of time. If DMB does not positioning well to customer's mind quickly, another products like Wibro, IPTV, or HSPDA could replace it before it even spreads out. Therefore, positioning strategy is critical for success of DMB product. To make correct positioning strategy, one needs to understand how consumer interprets DMB and how consumer's interpretation can be changed via communication strategy. In this study, we try to investigate how consumer perceives a new product, like DMB and how AD strategy change consumer's perception. More specifically, the paper segment consumers into sub-groups based on their DMB perceptions and compare their characteristics in order to understand how they perceive DMB. And, expose them different printed ADs that have messages guiding consumer think DMB in specific ways, either cellular phone or personal TV. Research Question 1: Segment consumers according to perceptions about DMB and compare characteristics of segmentations. Research Question 2: Compare perceptions about DMB after AD that induces categorization of DMB in direction for each segment. If one understand and predict a direction in which consumer perceive a new product, firm can select target customers easily. We segment consumers according to their perception and analyze characteristics in order to find some variables that can influence perceptions, like prior experience, usage, or habit. And then, marketing people can use this variables to identify target customers and predict their perceptions. If one knows how customer's perception is changed via AD message, communication strategy could be constructed properly. Specially, information from segmented customers helps to develop efficient AD strategy for segment who has prior perception. Research framework consists of two measurements and one treatment, O1 X O2. First observation is for collecting information about consumer's perception and their characteristics. Based on first observation, the paper segment consumers into two groups, one group perceives DMB similar to Cellular phone and the other group perceives DMB similar to TV. And compare characteristics of two segments in order to find reason why they perceive DMB differently. Next, we expose two kinds of AD to subjects. One AD describes DMB as Cellular phone and the other Ad describes DMB as personal TV. When two ADs are exposed to subjects, consumers don't know their prior perception of DMB, in other words, which subject belongs 'similar-to-Cellular phone' segment or 'similar-to-TV' segment? However, we analyze the AD's effect differently for each segment. In research design, final observation is for investigating AD effect. Perception before AD is compared with perception after AD. Comparisons are made for each segment and for each AD. For the segment who perceives DMB similar to TV, AD that describes DMB as cellular phone could change the prior perception. And AD that describes DMB as personal TV, could enforce the prior perception. For data collection, subjects are selected from undergraduate students because they have basic knowledge about most digital equipments and have open attitude about a new product and media. Total number of subjects is 240. In order to measure perception about DMB, we use indirect measurement, comparison with other similar digital products. To select similar digital products, we pre-survey students and then finally select PDA, Car-TV, Cellular Phone, MP3 player, TV, and PSP. Quasi experiment is done at several classes under instructor's allowance. After brief introduction, prior knowledge, awareness, and usage about DMB as well as other digital instruments is asked and their similarities and perceived characteristics are measured. And then, two kinds of manipulated color-printed AD are distributed and similarities and perceived characteristics for DMB are re-measured. Finally purchase intension, AD attitude, manipulation check, and demographic variables are asked. Subjects are given small gift for participation. Stimuli are color-printed advertising. Their actual size is A4 and made after several pre-test from AD professionals and students. As results, consumers are segmented into two subgroups based on their perceptions of DMB. Similarity measure between DMB and cellular phone and similarity measure between DMB and TV are used to classify consumers. If subject whose first measure is less than the second measure, she is classified into segment A and segment A is characterized as they perceive DMB like TV. Otherwise, they are classified as segment B, who perceives DMB like cellular phone. Discriminant analysis on these groups with their characteristics of usage and attitude shows that Segment A knows much about DMB and uses a lot of digital instrument. Segment B, who thinks DMB as cellular phone doesn't know well about DMB and not familiar with other digital instruments. So, consumers with higher knowledge perceive DMB similar to TV because launching DMB advertising lead consumer think DMB as TV. Consumers with less interest on digital products don't know well about DMB AD and then think DMB as cellular phone. In order to investigate perceptions of DMB as well as other digital instruments, we apply Proxscal analysis, Multidimensional Scaling technique at SPSS statistical package. At first step, subjects are presented 21 pairs of 7 digital instruments and evaluate similarity judgments on 7 point scale. And for each segment, their similarity judgments are averaged and similarity matrix is made. Secondly, Proxscal analysis of segment A and B are done. At third stage, get similarity judgment between DMB and other digital instruments after AD exposure. Lastly, similarity judgments of group A-1, A-2, B-1, and B-2 are named as 'after DMB' and put them into matrix made at the first stage. Then apply Proxscal analysis on these matrixes and check the positional difference of DMB and after DMB. The results show that map of segment A, who perceives DMB similar as TV, shows that DMB position closer to TV than to Cellular phone as expected. Map of segment B, who perceive DMB similar as cellular phone shows that DMB position closer to Cellular phone than to TV as expected. Stress value and R-square is acceptable. And, change results after stimuli, manipulated Advertising show that AD makes DMB perception bent toward Cellular phone when Cellular phone-like AD is exposed, and that DMB positioning move towards Car-TV which is more personalized one when TV-like AD is exposed. It is true for both segment, A and B, consistently. Furthermore, the paper apply correspondence analysis to the same data and find almost the same results. The paper answers two main research questions. The first one is that perception about a new product is made mainly from prior experience. And the second one is that AD is effective in changing and enforcing perception. In addition to above, we extend perception change to purchase intention. Purchase intention is high when AD enforces original perception. AD that shows DMB like TV makes worst intention. This paper has limitations and issues to be pursed in near future. Methodologically, current methodology can't provide statistical test on the perceptual change, since classical MDS models, like Proxscal and correspondence analysis are not probability models. So, a new probability MDS model for testing hypothesis about configuration needs to be developed. Next, advertising message needs to be developed more rigorously from theoretical and managerial perspective. Also experimental procedure could be improved for more realistic data collection. For example, web-based experiment and real product stimuli and multimedia presentation could be employed. Or, one can display products together in simulated shop. In addition, demand and social desirability threats of internal validity could influence on the results. In order to handle the threats, results of the model-intended advertising and other "pseudo" advertising could be compared. Furthermore, one can try various level of innovativeness in order to check whether it make any different results (cf. Moon 2006). In addition, if one can create hypothetical product that is really innovative and new for research, it helps to make a vacant impression status and then to study how to form impression in more rigorous way.

• The Mathematical Education
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• v.24 no.2
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• pp.105-116
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• 1986

For any thought and knowledge, its growth and development has close relation with the society where it is developed and grow. As Feuerbach says, the birth of spirit needs an existence of two human beings, i. e. the social background, as well as the birth of body does. But, at the educational viewpoint, the spread and the growth of such a thought or knowledge that influence favorably the development of a society must be also considered. We would discuss the goal and the function of mathematics education in relation with the prosperity of a technological civilization. But, the goal and the function are not unrelated with the spiritual culture which is basis of the technological civilization. Most societies of today can be called open democratic societies or societies which are at least standing such. The concept of rationality in such societies is a methodological principle which completes the democratic society. At the same time, it is asserted as an educational value concept which explains comprehensively the standpoint and the attitude of one who is educated in such a society. Especially, we can considered the cultivation of a mathematical thinking or a logical thinking in the goal of mathematics education as a concept which is included in such an educational value concept. The use of the concept of rationality depends on various viewpoints and criterions. We can analyze the concept of rationality at two aspects, one is the aspect of human behavior and the other is that of human belief or knowledge. Generally speaking, the rationality in human behavior means a problem solving power or a reasoning power as an instrument, i. e. the human economical cast of mind. But, the conceptual condition like this cannot include value concept. On the other hand, the rationality in human knowledge is related with the problem of rationality in human belief. For any statement which represents a certain sort of knowledge, its universal validity cannot be assured. The statements of value judgment which represent the philosophical knowledge cannot but relate to the argument on the rationality in human belief, because their finality do not easily turn out to be true or false. The positive statements in science also relate to the argument on the rationality in human belief, because there are no necessary relations between the proposition which states the all-pervasive rule and the proposition which is induced from the results of observation. Especially, the logical statement in logic or mathematics resolves itself into a question of the rationality in human belief after all, because all the logical proposition have their logical propriety in a certain deductive system which must start from some axioms, and the selection and construction of an axiomatic system cannot but depend on the belief of a man himself. Thus, we can conclude that a question of the rationality in knowledge or belief is a question of the rationality both in the content of belief or knowledge and in the process where one holds his own belief. And the rationality of both the content and the process is namely an deal form of a human ability and attitude in one's rational behavior. Considering the advancement of mathematical knowledge, we can say that mathematics is a good example which reflects such a human rationality, i. e. the human ability and attitude. By this property of mathematics itself, mathematics is deeply rooted as a good. subject which as needed in moulding the ability and attitude of a rational person who contributes to the development of the open democratic society he belongs to. But, it is needed to analyze the practicing and pursuing the rationality especially in mathematics education. Mathematics teacher must aim the rationality of process where the mathematical belief is maintained. In fact, there is no problem in the rationality of content as long the mathematics teacher does not draw mathematical conclusions without bases. But, in the mathematical activities he presents in his class, mathematics teacher must be able to show hem together with what even his own belief on the efficiency and propriety of mathematical activites can be altered and advanced by a new thinking or new experiences.

• Journal of Astronomy and Space Sciences
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• v.22 no.3
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• pp.329-352
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• 2005

Long term observations of full-disk Lyman-o irradiance have been made by the instruments on various satellites. In addition, several sounding rockets dating back to the 1950s and up through the present have measured the $Lyman-{\alpha}$ irradiance. Previous full disk $Lyman-{\alpha}$ images of the sun have been very interesting and useful scientifically, but have been only five-minute 'snapshots' obtained on sounding rocket flights. All of these observations to date have been snapshots, with no time resolution to observe changes in the chromospheric structure as a result of the evolving magnetic field, and its effect on the Lyman-o intensity. The $Lyman-{\alpha}$ Imaging Solar Telescope(LIST) can provide a unique opportunity for the study of the sun in the $Lyman-{\alpha}$ region with the high time and spatial resolution for the first time. Up to the 2nd year development, the preliminary design of the optics, mechanical structure and electronics system has been completed. Also the mechanical structure analysis, thermal analysis were performed and the material for the structure was chosen as a result of these analyses. And the test plan and the verification matrix were decided. The operation systems, technical and scientific operation, were studied and finally decided. Those are the technical operation, mechanical working modes for the observation and safety, the scientific operation and the process of the acquired data. The basic techniques acquired through the development of satellite based solar telescope are essential for the construction of space environment forecast system in the future. The techniques which we developed through this study, like mechanical, optical and data processing techniques, could be applied extensively not only to the process of the future production of flight models of this kind, but also to the related industries. Also, we can utilize the scientific achievements which are obtained throughout the project And these can be utilized to build a high resolution photometric detectors for military and commercial purposes. It is also believed that we will be able to apply several acquired techniques for the development of the Korean satellite projects in the future.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.569-578
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• 2007

This study was performed to compare the shear bond strength of self etching system and two bottle bonding system with or without laser preparation. Group I was prepared with high speed rotary instrument and $Prompt^{TM}$ L-$Pop^{TM}$, group II with Er:YAG laser and $Prompt^{TM}$ L-$Pop^{TM}$, group III with Er:YAG laser, 37% phosphoric acid and Single bond, group IV with Er:YAG laser and Single bond and group V with high speed, etching and Single bond. And also observation of the prepared and etched dentin surface were performed under scanning electro-microscope. The possibility of clinical application of laser preparation which might have an advantage to reduce pain for children with less unfavorable noise were evaluated. The results obtained are as follows; 1. Group V showed significantly higher bond strength than other groups. And group IV showed significantly lower bond strength than other groups. 2. There was no significant difference between group I and group III. 3. Group II showed significantly lower bond strength than group I, III, V, but showed significantly higher bond strength than group IV. 4. Under scanning electro-microscope, laser-preparated dentin surface showed high irregularity and no smear layer. The surface showed less irregularities and more exposed dentinal tubules with etching. Laser preparation has many advantages over conventional tooth preparation. But this method showed lower resin bonding strength. Laser preparated tooth surface differed from the conventionally preparated tooth surface. More researches are needed on suitable methods for laser preparated dentin surface.