• Journal of the Korean Chemical Society
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• v.19 no.3
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• pp.186-192
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• 1975

In the course of anthracite briquet combustion, air draft is usually controlled to continue burning of definite amount of briquet in the conventional hollow clay cylinder with air inlet hole open for given time, so that a large amount of CO tends to be produced. Therefore, it is necessary to establish an improved combustion process to depress the yielding rate of CO and for this purpose, we performed a basic experiment in which combustion rate of CO was measured in the mixture of $N_2, O_2 $and CO gas with or without the presence charcoal at the various temperature. The observed results showed that the burning temperature of CO is about 680${\sim}700^{\circ}C$, further burning rate of it was increased with increasing the amount of draft. From these facts, longer combustion time and low CO generation are thus contradictory to each other and it has been long desired to make those two compatible somehow. The purpose of the present investigation lies in designing an effective new briquet stove to meet the above requirements. The essential feature of the new briquet stove consisted in the use of two hollow iron cylinders with different inside diameter. A cylindrical air jacket thus formed served as a path through which small amount of secondary air run from the bottom of the stove to the upper vent holes. Heat exchange occurred between the upgoing secondary air and the burning briquet, which lowered the combustion temperature of the briquet. The results observed were selfevident as anticipated. It was confirmed that the combustion time was increased tolerably due to the heat loss from the combustion zone and that CO in the flue gas was reoxidized at the upper portion of the stove by the upgoing hot secondary air. By this reoxidation reaction the concentration of CO in the flue gas was found to be about 1/20 of that in case the conventional clay cylinder was used as briquet jacket.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.205-205
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• 2013

테라헤르쯔(terahertz: THz)파는 0.1~10 THz 의 범위로 적외선과 방송파 사이에 광대역 주파수 스펙트럼을 차지하고 있으며 직진성, 투과성, 그리고 낮은 에너지 (meV)를 가지고 있어 비 파괴적이고 무해한 장점을 지니고 있다. Ti:sapphire laser와 같은 femto-pulse source 등이 많은 발전이 되어 현재 많은 연구와 발전이 이루어지고 있다. femto-pulse source를 이용한 THz 응용에서는 높은 저항, 큰 전자 이동도, 그리고 아주 짧은 전하수명의 기판을 요구하는데 저온에서 성장한 (low-temperature grown : LT) GaAs는 격자 내에 Gallium 자리에 Arsenic이 치환 하면서 AsGa antisite가 발생하여 전하수명을 짧아지는 것을 응용하여 가장 많이 이용되고 있다. 현재 THz 응용분야에서 보다 작고 가격경쟁력이 있는 광통신을 이용한 THz photomixer등이 활발히 연구 하고 있다. 광섬유 내에서 손실과 분산이 최소값을 가지는 부분이 1.55 ${\mu}m$ 부근이고 In0.53Ga0.47As 기판을 이용하였을 때 여기에 완벽하게 만족하게 된다. 하지만 LT-InGaAs 의 경우 AsGa antisite로 인하여 carrier lifetime은 짧아지지만 높은 n-type 전하밀도를 가지게 된다. 이때 Be을 doping하여 전하밀도를 보상하여 높은 저항을 유지해야 하는데 Be의 활성화를 위해서는 열처리를 필요로 한다. 하지만 열처리를 하면 carrier lifetime이 길어지기 때문에 carrier lifetime과 저항을 적절히 조율해야 한다. 이는 물질자체의 특성이기 때문에 InGaAs는 GaAs보다 낮은 amplitude와 짧은 cut-off frequency를 가진다. 본 연구에서는 보다 높은 저항을 얻기 위하여 molecular beam epitaxy를 이용하여 semi-insulating InP:Fe 기판위에 격자 정합된 InGaAs:Be/InAlAs multi quantum well (MQW)를 온도별 ($250{\sim}400^{\circ}C$), 주기별 (50~150)로 성장을 하였고 이때 InGaAs layer의 Be doping level은 $2{\times}1018\;cm^{-3}$, Ex-situ annealing은 $550^{\circ}C$에서 10분으로 고정 하였다. THz 발생 실험에서는 InGaAs/InAlAs MQW은 4000 pA로 1,000 pA를 가지는 InGaAs epilayer보다 4배 높은 전류 신호를 얻을 수 있었고 모든 샘플이 2 THz에서 cut-off frequency를 가지고 있었다. THz 검출 실험에서는 LT-InGaAs:Be epilayer LT-InGaAs:Be/InAlAs, HT-InGaAs/InAlAs 샘플이 각각 180, 9000, 12000 pA의 전류신호를 가지고 있었고 모든 샘플이 2 THz에서 cut-off frequency를 가지고 있었다. HT-InGaAs/InAlAs MQW를 이용한 검출실험에서는 InGaAs layer가 defect free이지만 LT-InGaAs:Be/ InAlAs MQW 보다 높은 전류 신호를 얻을 수 있었다. 이는 InAlAs layer가 저항만 높이는 것뿐만 아니라 carrier trapping layer로써의 역할도 하는 것으로 사료된다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.1
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• pp.29-37
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• 1999

In this study, we have prepared PLT thin films having various La concentrations by using sol-gel method and studied on the effect of La concentration on the electrical properties of PLT thin films. As the La concentration increases from 5mol% to 28mol%, the dielectric constant at 10kHz increases from 428 to 761, while the loss tangent decreases from 0.063 to 0.024. Also, the leakage current density at 150kV/cm has a tendency to decrease from 6.96${\mu}A/cm^2$ to 0.79${\mu}A/cm^2$. In the result of hysteresis loops of PLT thin films, the remanent polariation and the coercive field decrease from 9.55${\mu}C/cm^2$ to 1.10${\mu}C/cm^2$ and from 46.4kV/cm to 13.7kV/cm, respectively. With the result of the fatigue test on the PLT thin films, we have found that the fatigue properties are improved remarkably as the La concentration increases from 5 mol% to 28mol%. In particular, the PLT28) has paraelectric phase and its charge storage clensity and leakage current density at 5V are 134fC/${\mu}cm^2$ and 1.01${\mu}A/cm^2$, respectively. The remanent polarization and coercive field of the PLT(10) film are 6.96${\mu}C/cm^2$ and 40.2kV/cm, respectively. After applying of $10^9$ square pulses with ${\pm}5V$, the remanent polarilzation of the PLT(10) film decreases about 20% from the initial state. In the results, we conclude that the 10mol% and the 28mol% La doped PLT thin films are very suitable for the capacitor dielectrics of new generation of DRAM and NVFRAM respecitively.

• Korean journal of applied entomology
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• v.47 no.2
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• pp.163-168
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• 2008

Temperature dependent development of Tetranychus. urticae Koch was studied on the leaf of eggplant at 17, 22, 27, 32 and $37^{\circ}C$. T. urticae showed a minimum mortality at $27^{\circ}C$ and it increased at higher or lower temperatures than $27^{\circ}C$. The hatchability was low at 17 and $37^{\circ}C$. The duration of development decreased with increasing temperatures i.e., 5.3d at $37^{\circ}C$ and 25.8d at $17^{\circ}C$. Linear regression analysis of temperature vs. rate of development yielded the higher $r^2{\geq}0.88$ resulting in a good fit of the estimated line in the range of $17{\sim}37^{\circ}C$. Developmental zero temperature was $12.5^{\circ}C$ for the entire immature stage of female and $12.8^{\circ}C$ for that of male. Thermal constants were 80.5 and 74.7 degree days for those of female and male, respectively. Adult life span and oviposition period decreased with increasing temperatures. The number of eggs laid per female peaked at 141.0 eggs at $27^{\circ}C$, while that was a minimum 78.0 eggs at $37^{\circ}C$. Rate of hatchability, ratio of female, and $R_o$ were increased up to $27^{\circ}C$, and than declined thereafter. Intrinsic rate of natural increase (Rm) increased with rising temperatures and showed a maximum 0.5652 at $37^{\circ}C$. Also, ${\lambda}$ increased with increasing temperature. Doubling time (Dt) and generation time (T) decreased with increasing temperature.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.1029-1042
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• 2021

As part of the next-generation Compact Advanced Satellite 500 (CAS500) project, CAS500-4 is scheduled to be launched in 2025 focusing on the remote sensing of agriculture and forestry. To obtain quantitative information on vegetation from satellite images, it is necessary to acquire surface reflectance through atmospheric correction. Thus, it is essential to develop an atmospheric correction method suitable for CAS500-4. Since the absorption and scattering characteristics in the atmosphere vary depending on the wavelength, it is needed to analyze the sensitivity of atmospheric correction parameters such as aerosol optical depth (AOD) and water vapor (WV) considering the wavelengths of CAS500-4. In addition, as CAS500-4 has only five channels (blue, green, red, red edge, and near-infrared), making it difficult to directly calculate key parameters for atmospheric correction, external parameter data should be used. Therefore, thisstudy performed a sensitivity analysis of the key parameters (AOD, WV, and O₃) using the simulated images based on Sentinel-2 satellite data, which has similar wavelength specifications to CAS500-4, and examined the possibility of using the products of GEO-KOMPSAT-2A (GK2A) as atmospheric parameters. The sensitivity analysisshowed that AOD wasthe most important parameter with greater sensitivity in visible channels than in the near-infrared region. In particular, since AOD change of 20% causes about a 100% error rate in the blue channel surface reflectance in forests, a highly reliable AOD is needed to obtain accurate surface reflectance. The atmospherically corrected surface reflectance based on the GK2A AOD and WV was compared with the Sentinel-2 L2A reflectance data through the separability index of the known land cover pixels. The result showed that two corrected surface reflectance had similar Seperability index (SI) values, the atmospheric corrected surface reflectance based on the GK2A AOD showed higher SI than the Sentinel-2 L2A reflectance data in short-wavelength channels. Thus, it is judged that the parameters provided by GK2A can be fully utilized for atmospheric correction of the CAS500-4. The research findings will provide a basis for atmospheric correction of the CAS500-4 in the future.

• Korean journal of applied entomology
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• v.59 no.3
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• pp.185-202
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• 2020

The diapause induction season in Ostrinia furnacalis (Lepidoptera: Crambidae) was estimated in Suwon. Three batches of adult generations were observed, the first one from early May to early July, the second from early or mid-July to early or mid-August, and the third from mid-August to October. In outdoor larval rearing, colony rearing occurring from mid-July to mid-August produced both non-overwintering and overwintering larvae, whereas late-reared colonies produced only overwintering larvae. Larvae collected during July and August in maize fields produced both non-overwintering and overwintering larvae, whereas late-collected larvae produced only overwintering larvae. The results indicated that O. furnacalis has a bi- or trivoltine complex life cycle in this area. In the laboratory, when larvae of all instars within 9 h after molting were first treated to a diapause induction condition (11:13 h = light:dark photoperiod and 20℃), almost all larvae were induced to diapause. However, when similar treatments were conducted age-specifically for the 5th instar larvae, diapause induction rates in 3- and 4-day-old larvae of the 5th instar decreased. In contrast, when larvae were subjected to the diapause induction treatment only during the periods from the hatching stage to the 2nd, 3rd, and 4th instar, almost all larvae were not induced to diapause. The results suggest that the early age of the 5th larval instar is the last stage for sensitivity to diapause induction stimuli. In the diapause-induced larvae, hemolymph trehalose content increased and body supercooling points dropped, compared with those in non-diapause larvae.

• Journal of Korean Academy of Nursing
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• v.28 no.4
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• pp.1047-1059
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• 1998

Senile Dementia is one of the dispositional mental disorder which has been known to the world since Hippocratic age. It has become a wide-spread social problem all over the world because of chronic disease processes and the demands of dependent care for several years as well as improbability of treatment of it at the causal level. Essentially, life styles of the older generation differ from those of the younger generation. While the fomer is used to the patriarchal system and the spirit of filial piet and respect, the latter is pragmatized and individualized under the effects of the Western material civilization. These differences between the two generations cause conflict between family members. In particular, the pain and conflict of care-givers who take care of a totally dependent dementia patient not only is inciting to the collapse of the family union, but is expanding into a serious social problem. According to this practical difficulty, this study has tried to compare dementia care-givers' experiences inter-culturally and to help set up more proper nursing interventions, describing and explaining them through ethnographies by participant observation and in-depth interviews that enable seeing them in a more close, honest and certain way. It also tries to provide a theoetical model of nusing care for dementia patients which is proper to Korean culture. This study is composed of 12 participants (4 males, 8 females) whose ages range from 37-71 years. The relations of patients are 5 spouses(3 husbands, 2 wives), 4 daughters-in-law, 2 daughters, and 1 son-in-law. The following are the care-givers' meaning of experiences that results of the study shows. The first is "psychological conflict". It contains the minds of getting angry, reproaching, being driven to dispair, blaming oneself, giving up lives, and being afraid, hopeless, and resigned. The second is "physical, social and psychological pressure" . At this stage, care-givers are shown to be under stress of both body and soul for the lack of freedom and tiredness. They also feel constraint because they hardly cope with the care and live through others' eyes. The third is "isolation". It makes the relationship of patient care-giver to be estranged, without understanding each other. They, also, experience indifference such as being upset and left alone. The forth is "acceptance" They gradually have compassion, bear up and then adapt themselves to the circumstances they are in. The fifth is "love". Now they learn to reward the other with love. It is also shown that this stage contains the process of winning others' recognition. The final is "hope". In this stage they really want situations to go smoothly and hope everything will be O.K. These consequences enable us to summarize the principles of cue experience such as, in the early stage, negative response such as physical·psychological confusion, pain and conflict are primary. Then the stage of acceptance emerges. It is an initial positive response phase when care-givers may admit their situations. As time passes by a positive response stage emerges. At last they have love and hope. Three stages we noted above : however, there are never consistent situations. Rather it gradually comes into the stage of acceptance, repeating continuous conflict, pressure and isolation. If any interest and understanding of families or the support of surrounding society lack, it will again be converted to negative responses sooner or later. Otherwise, positive responses like hope and love can be encouraged if the family and the surroundings give active aids and understanding. After all, the principles of dementia care experiences neither stay at any stage, nor develop from negative stages to positive stages steadily. They are cycling systems in which negative responses and positive responses are constantly being converted. I would like to suggest the following based on the above conclusions : First, the systematic and planned education of dementia should be performed in order to enhance public relations. Second, a special medical treatment center which deals with dementia, under government's charge, should be managed. Third, the various studies approaching dementia care experiences result in the development of more reasonable and useful nursing guidelines.

• Korean Journal of Occupational Health Nursing
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• v.11 no.1
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• pp.13-30
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• 2002

Industrial shift workers feels suffer mental stresses which are caused by unfamiliar day sleep, noisy environment, sleeping disorder by bright light, unusual contacts with family, difficulty in meeting with friends or having formal social meetings and other social limitations such as the use of transportation. Such stresses influence health of the workers negatively. Thus the health promotion policy for shift workers should be made considering the workers' ways of living and shift work specially. This study attempted to provide basic information for development of the health promotion program for industrial shift workers by examining predictive factors influencing health promotion behaviors of those workers. In designing the study, three power generation plants located in Pusan and south Kyungsang province were randomly selected and therefrom 280 workers at central control, boiler and turbine rooms and environmental chemistry parts whose processes require shift works were sampled as subjects of the study. Data were collected two times from September 17 to October 8, 1999 using questionnaires with helps of safety and health managers of the plants. The questionnaires were distributed through mails or direct visits. Means for the study included the measurement tool of health promotion behavior provided by Park(1995), the tool of self-efficacy measurement by Suh(1995), the tool of internal locus of control measurement by Oh(1987), the measurement tool of perceived health state by Park(1995) and the tool of social support measurement by Paek(1995). The collected data were analyzed using SPSS program. Controlling factors of the subjects were evaluated in terms of frequency and percentage ratio Perceived factors and health promotion behaviors of the subjects were done so in terms of mean and standard deviation, and average mark and standard deviation, respectively. Relations between controlling and perceived factors were analyzed using t-test and ANOVA and those between perceived factors and the performance of health promotion behaviors, using Pearson's Correlation Coefficient. The performance of health promotion behaviors was tested using t-test, ANOVA and post multi-comparison (Scheffe test). Predictive factors of health promotion behavior were examined through the Stepwise Multiple Regression Analysis. Results of the study are summarized as follows. 1. The performance of health promotion behaviors by the subjects was evaluated as having the value of mean, $161.27{\pm}26.73$ points(min.:60, max.:240) and average mark, $2.68{\pm}0.44$ points(min.:1, max.:4). When the performance was analyzed according to related aspects, it showed the highest level in harmonious relation with average mark, $3.15{\pm}.56$ points, followed by hygienic life($3.03{\pm}.55$), self-realization ($2.84{\pm}.55$), emotional support($2.73{\pm}.61$), regular meals($2.71{\pm}.76$), self-control($2.62{\pm}.63$), health diet($2.62{\pm}.56$), rest and sleep($2.60{\pm}.59$), exercise and activity($2.53{\pm}.57$), diet control($2.52{\pm}.56$) and special health management($2.06{\pm}.65$). 2. In relations between perceived factors of the subjects(self-efficacy, internal locus of control, perceived health state) and the performance of health promotion behaviors, the performance was found having significantly pure relations with self-efficacy (r=.524, P=.000), internal locus of control (r=.225, P=.000) and perceived health state(r=.244, P=.000). The higher each evaluated point of the three factors was, the higher the performance was in level. 3. When relations between the controlling factors(demography-based social, health-related, job-related and human relations characteristics) and the performance of health promotion behaviors were analyzed, the performance showed significant differences according to marital status (t=2.09, P= .03), religion(F=3.93, P= .00) and participation in religious activities (F=8.10, P= .00) out of demography-based characteristics, medical examination results (F=7.20, P= .00) and methods of the collection of health knowledge and information(F=3.41, P= .01) and methods of desired health education(F=3.41, P= .01) out of health-related characteristics, detrimental factors perception(F=4.49, P= .01) and job satisfaction(F=8.41, P= .00) out of job-related characteristics and social support(F=14.69, P= .00) out of human relations characteristics. 4. The factor which is a variable predicting best the performance of health promotion behaviors by the subjects was the self-efficacy accounting for 27.4% of the prediction, followed by participation in religious activities, social support, job satisfaction, received health state and internal locus of control in order all of which totally account for 41.0%. In conclusion, the predictive factor which most influence the performance of health promotion behaviors by shift workers was self-efficacy. To promote the sense, therefore, it is necessary to develop the nursing intervention program considering predictive factors as variables identified in this study. Further industrial nurses should play their roles actively to help shift workers increase their capability of self-management of health.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.3
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• pp.103-115
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• 2000

The formation of brown-colored precipitates is one of the serious problems frequently encountered in the development and supply of groundwater in Korea, because by it the water exceeds the drinking water standard in terms of color. taste. turbidity and dissolved iron concentration and of often results in scaling problem within the water supplying system. In groundwaters from the Pajoo area, brown precipitates are typically formed in a few hours after pumping-out. In this paper we examine the process of the brown precipitates' formation using the equilibrium thermodynamic and kinetic approaches, in order to understand the origin and geochemical pathway of the generation of turbidity in groundwater. The results of this study are used to suggest not only the proper pumping technique to minimize the formation of precipitates but also the optimal design of water treatment methods to improve the water quality. The bed-rock groundwater in the Pajoo area belongs to the Ca-$HCO_3$type that was evolved through water/rock (gneiss) interaction. Based on SEM-EDS and XRD analyses, the precipitates are identified as an amorphous, Fe-bearing oxides or hydroxides. By the use of multi-step filtration with pore sizes of 6, 4, 1, 0.45 and 0.2 $\mu\textrm{m}$, the precipitates mostly fall in the colloidal size (1 to 0.45 $\mu\textrm{m}$) but are concentrated (about 81%) in the range of 1 to 6 $\mu\textrm{m}$in teams of mass (weight) distribution. Large amounts of dissolved iron were possibly originated from dissolution of clinochlore in cataclasite which contains high amounts of Fe (up to 3 wt.%). The calculation of saturation index (using a computer code PHREEQC), as well as the examination of pH-Eh stability relations, also indicate that the final precipitates are Fe-oxy-hydroxide that is formed by the change of water chemistry (mainly, oxidation) due to the exposure to oxygen during the pumping-out of Fe(II)-bearing, reduced groundwater. After pumping-out, the groundwater shows the progressive decreases of pH, DO and alkalinity with elapsed time. However, turbidity increases and then decreases with time. The decrease of dissolved Fe concentration as a function of elapsed time after pumping-out is expressed as a regression equation Fe(II)=10.l exp(-0.0009t). The oxidation reaction due to the influx of free oxygen during the pumping and storage of groundwater results in the formation of brown precipitates, which is dependent on time, $Po_2$and pH. In order to obtain drinkable water quality, therefore, the precipitates should be removed by filtering after the stepwise storage and aeration in tanks with sufficient volume for sufficient time. Particle size distribution data also suggest that step-wise filtration would be cost-effective. To minimize the scaling within wells, the continued (if possible) pumping within the optimum pumping rate is recommended because this technique will be most effective for minimizing the mixing between deep Fe(II)-rich water and shallow $O_2$-rich water. The simultaneous pumping of shallow $O_2$-rich water in different wells is also recommended.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.1
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• pp.1-17
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• 2002

The purpose of this study is to examine the possibility of thermal injury to bone tissues during an implant site preparation under the same condition as a typical clinical practice of $Br{\aa}nemark$ implant system. All the burs for $Br{\aa}nemark$ implant system were studied except the round bur The experiments involved 880 drilling cases : 50 cases for each of the 5 steps of NP, 5 steps of RP, and 7 steps of WP, all including srew tap, and 30 cases of 2mm twist drill. For precision drilling, a precision handpiece restraining system was developed (Eungyong Machinery Co., Korea). The system kept the drill parallel to the drilling path and allowed horizontal adjustment of the drill with as little as $1{\mu}m$ increment. The thermocouple insertion hole. that is 0.9mm in diameter and 8mm in depth, was prepared 0.2mm away from the tapping bur the last drilling step. The temperatures due to countersink, pilot drill, and other drills were measured at the surface of the bone, at the depths of 4mm and 8mm respectively. Countersink drilling temperature was measured by attaching the tip of a thermocouple at the rim of the countersink. To assure temperature measurement at the desired depths, 'bent-thermocouples' with their tips of 4 and 8mm bent at $120^{\circ}$ were used. The profiles of temperature variation were recorded continuously at one second interval using a thermometer with memory function (Fluke Co. U.S.A.) and 0.7mm thermocouples (Omega Co., U.S.A.). To simulate typical clinical conditions, 35mm square samples of bovine scapular bone were utilized. The samples were approximately 20mm thick with the cortical thickness on the drilling side ranging from 1 to 2mm. A sample was placed in a container of saline solution so that its lower half is submerged into the solution and the upper half exposed to the room air, which averaged $24.9^{\circ}C$. The temperature of the saline solution was maintained at $36.5^{\circ}C$ using an electric heater (J. O Tech Co., Korea). This experimental condition was similar to that of a patient s opened mouth. The study revealed that a 2mm twist drill required greatest attention. As a guide drill, a twist drill is required to bore through a 'virgin bone,' rather than merely enlarging an already drilled hole as is the case with other drills. This typically generates greater amount of heat. Furthermore, one tends to apply a greater pressure to overcome drilling difficulty, thus producing even greater amount heat. 150 experiments were conducted for 2mm twist drill. For 140 cases, drill pressure of 750g was sufficient, and 10 cases required additional 500 or 100g of drilling pressure. In case of the former. 3 of the 140 cases produced the temperature greater than $47^{\circ}C$, the threshold temperature of degeneration of bone tissue (1983. Eriksson et al.) which is also the reference temperature in this study. In each of the 10 cases requiring extra pressure, the temperature exceeded the reference temperature. More significantly, a surge of heat was observed in each of these cases This observations led to addtional 20 drilling experiments on dense bones. For 10 of these cases, the pressure of 1,250g was applied. For the other 10, 1.750g were applied. In each of these cases, it was also observed that the temperature rose abruptly far above the thresh old temperature of $47^{\circ}C$, sometimes even to 70 or $80^{\circ}C$. It was also observed that the increased drilling pressure influenced the shortening of drilling time more than the rise of drilling temperature. This suggests the desirability of clinically reconsidering application of extra pressures to prevent possible injury to bone tissues. An analysis of these two extra pressure groups of 1,250g and 1,750g revealed that the t-statistics for reduced amount of drilling time due to extra pressure and increased peak temperature due to the same were 10.80 and 2.08 respectively suggesting that drilling time was more influenced than temperature. All the subsequent drillings after the drilling with a 2mm twist drill did not produce excessive heat, i.e. the heat generation is at the same or below the body temperature level. Some of screw tap, pilot, and countersink showed negative correlation coefficients between the generated heat and the drilling time. indicating the more the drilling time, the lower the temperature. The study also revealed that the drilling time was increased as a function of frequency of the use of the drill. Under the drilling pressure of 750g, it was revealed that the drilling time for an old twist drill that has already drilled 40 times was 4.5 times longer than a new drill The measurement was taken for the first 10 drillings of a new drill and 10 drillings of an old drill that has already been used for 40 drillings. 'Test Statistics' of small samples t-test was 3.49, confirming that the used twist drills require longer drilling time than new ones. On the other hand, it was revealed that there was no significant difference in drilling temperature between the new drill and the old twist drill. Finally, the following conclusions were reached from this study : 1 Used drilling bur causes almost no change in drilling temperature but increase in drilling time through 50 drillings under the manufacturer-recommended cooling conditions and the drilling pressure of 750g. 2. The heat that is generated through drilling mattered only in the case of 2mm twist drills, the first drill to be used in bone drilling process for all the other drills there is no significant problem. 3. If the drilling pressure is increased when a 2mm twist drill reaches a dense bone, the temperature rises abruptly even under the manufacturer-recommended cooling conditions. 4. Drilling heat was the highest at the final moment of the drilling process.