• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.71-84
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• 2003

The metallic shell of soil-steel structures are so weak in bending moment that it should sustain the applied load by the interaction of the backfill soil around the structures. The shell can be subjected to excessive bending moment during side backfilling or under live-load when the soil cover is less than the minimum value. The current design code specifies the allowable deformation and Duncan(1979) and McGrath et al.(2001) suggested the strength analysis methods to limit the moments by the plastic capacity of the shell. However, the allowable deformation is an empirically determined value and the strength analysis methods are based on the results of FE analysis, hence the experimental verification is necessary. In this study, the full-scale tests were conducted on the high-profile arch to investigate its behaviors during backfilling and under static live-loads. Based on the measurements, the allowable deformation of the tested structure could be estimated to be 1.45% of rise, which is smaller than the specified allowable deformation. The comparison between the measurements and the results of two strength analyses indicate that Duncan underestimates the earth-load moment and overestimates the live-load moment, while McGrath et al. predicts both values close to the actual values. However, as the predicted factors of safeties using two methods coincide with the actual factor of safety, it can be concluded that both methods can predict the structural stability under live-loads adequately when the cover is less than the minimum.

• Asia pacific journal of information systems
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• v.18 no.3
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• pp.45-65
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• 2008

The rapid growth of the Internet has increased the amount of transmission of personally identifiable information. At the same time, with new Internet related technologies, organizations are trying to collect and access more personal information than before, which in turn makes individuals concern more about their information privacy. For their successful businesses, organizations have tried to alleviate these concerns in two ways: (1) by offering privacy policies that promise certain level of privacy protection; (2) by offering benefits such as financial gains or convenience. In this paper, we interpret these actions in the context of the information processing theory of motivation. This paper follows Hann et al.(2007)'s methods to analyze Internet users privacy concerns in Korea and tries to compare the findings. Our research objectives are as follows: First, we analyze privacy concern mitigation strategies in the framework of the expectancy theory of motivation. Subsequently, we show how the expectancy theory based framework is linked o the conjoint analysis. We empirically validate the predictions that the means to mitigate privacy concerns are associated with positive valences resulting in an increase in motivational score. In order to accommodate real-life contexts, we investigate these means in trade-off situation, where an organization may only be able to offer partially complete privacy protection and/or promotions and/or convenience, While privacy protection (secondary use, improper access) are associated with positive valences, we also find that financial gains can significantly increase the individuals' motivational score of a website in Korea. One important implication of this empirical analysis is that organizations may possess means to actively manage the privacy concerns of Internet users. Our findings show that privacy policies are valued by users in Korea just as in the US or Singapore. Hence, organizations can capitalize on this, by stating their privacy policy more prominently. Also organizations would better think of strategies or means that may increase online users' willingness to provide personal information. Since financial incentives also significantly increase the individuals' motivational score of website participation, we can quantify the value of website privacy protection in terms of monetary gains. We find that Korean Internet users value the total privacy protection (protection against errors, improper access, and secondary use of personal information) as worthy as KW 25,550, which is about US 28. Having done this conjoint analysis, we next adopt cluster analysis methodology. We identify two distinct segments of Korea's internet users-privacy guardians and information sellers, and convenience seekers. The immediate implication of our study is that firms with online presence must differentiate their services to serve these distinct segments to best meet the needs of segments with differing trade-offs between money and privacy concerns. Information sellers are distinguished from privacy guardians by prior experience of information provision, To the extent that businesses cannot observe an individual's prior experience, they must use indirect methods to induce segmentation by self-selection as suggested in classic economics literature of price discrimination, Businesses could use monetary rewards to attract information sellers to provide personal information. One step forward from the societal trends that emphasize the need of legal protection of information privacy, our study wants to encourage organizations and related authorities to have the viewpoints to consider both importance of privacy protection and the necessity of information trade for the growth of e-commerce.

• Clean Technology
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• v.17 no.1
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• pp.56-61
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• 2011

In this study, hydrocarcking of vacuum residue was carried out in an autoclave reactor at $450^{\circ}C$ and $500^{\circ}C$ with a commercial catalyst (HDM) and the quantitative product distributions were analyzed by GC-SIMDIS method or simple distillation. During catalytic hydrocracking, thermal cracking also occurred together with catalytic cracking and the higher conversion and selectivity of gasoline and naphtha were obtained at high reaction temperature. GC-SIMDIS and simple distillation revealed different results for the analysis of products produced at different hydrocracking temperatures; almost same results were obtained for the product produced at $500^{\circ}C$ but different ones for the product produced at $450^{\circ}C$. In the analysis of product produced at $450^{\circ}C$, the GC-SIMDIS showed that a main product was VGO while a main product in the simple distillation was diesel, which implies that the simple distillation for the $450^{\circ}C$ reaction was not accurate due to thermal cracking of the product by the simple distillation.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.127.1-127.1
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• 2011

In this paper, ZnO:Al thin films with c-axis preferred orientation were prepared on Soda lime glass substrates by RF magnetron sputtering technique. AZO thin film were prepared in order to clarify optimum conditions for growth of the thin film depending upon process, and then by changing a number of deposition conditions and substrate temperature conditions variously, structural and electrical characteristics were measured. For the manufacture of the AZO were vapor-deposited in the named order. It is well-known that post-annealing is an important method to improve crystal quality. For the annealing process, the dislocation nd other defects arise in the material and adsorption/decomposition occurs. The XRD patterns of the AZO films deposited with grey theory prediction design, annealed in a vacuum ambient($2.0{\times}10-3$Torr)at temperatures of 200, 300, 400 and $500^{\circ}C$ for a period of 30min. The diffraction patterns of all the films show the AZO films had a hexagonal wurtzite structure with a preferential orientation along the c-axis perpendicular to the substrate surface. As can be seen, the (002)peak intensities of the AZO films became more intense and sharper when the annealing temperature increased. On the other hand, When the annealing temperature was $500^{\circ}C$ the peak intensity decreased. The surface morphologies and surface toughness of films were examined by atomic force microscopy(AFM, XE-100, PSIA). Electrical resistivity, Gall mobility and carrier concentration were measured by Hall effect measuring system (HL5500PC, Accent optical Technology, USA). The optical absorption spectra of films in the ultraviolet-visibleinfrared( UV-Vis-IR) region were recorder by the UV spectrophotometer(U-3501, Hitachi, Japan). The resistivity, carrier concentration, and Hall mobility of ZnS deposited on glass substrate as a function of post-annealing.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.1
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• pp.58-70
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• 2001

For the successful treatment of complete denture, obtaining a good retention is essential. There are lots of factors affecting denture retention. Denture material, one of those factors affecting denture retention, was the subject of this study, and internal surface treatment also considered for the method of enhancing denture retention. Two resin(Lucitone $199^{(R)}$(heat cured resin) Vertex $CP^{(R)}$(self cured resin)) and two metal($Biosil^{(R)}$(Co-Cr alloy), $Vitallium^{(R)}$(Co-Cr alloy)) denture base materials were used for making test denture base. Newly developed device was used for measuring denture retention. After the retention was measured. We treated internal surface of test denture base with $50{\mu}m\;Al_2O_3$ powder, under 90psi, for 1 minute. Then the retention was measured again. The result was analyzed with K-S test, one-way ANOVA test and independent t-test to deter mine the significant differences as the 95% level of confidence. The results are as follows : In cases of without internal surface treatment, the retention was increased in order of $Vitallium^{(R)},\;Biosil^{(R)},\;Vertex CP^{(R)}$ and Lucitone $199^{(R)}$. Except between Vertex $CP^{(R)}$ and $Biosil^{(R)}$, retention of the other materials was significantly different (p<0.05). After the treatment of internal surface, the retention was increased in order of $Vitallium^{(R)},\;Biosil^{(R)},\;Lucno\;199^{(R)},\;Vertex\;CP^{(R)}$. Except between Lucitone $199^{(R)}$ and Vertex $CP^{(R)}$, $Vitallium^{(R)}$ and $Biosil^{(R)}$ the retention of remaining groups was significantly different each other (p<0.05). In the matter of each material, after the internal surface treatment the retention was increased with Vertex $CP^{(R)},\;Biosil^{(R)}\;and\;Vitallium^{(R)}$ and the value of differences were statistically significant. When we compare the retention of resin and metal denture base, the retention of both denture bases increased significantly with internal surface treatment, and resin denture base showed better retention. As the results show, selecting denture base material could be an important choice of complete denture treatment. To increase denture retention, internal surface treatment can be considered as a possible method.

• Economic and Environmental Geology
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• v.19 no.spc
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• pp.19-41
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• 1986

Structural, radioactive, petrological, petrochemical, mineralogical and stable isotopic study as well as the review of previous studies of the uranium-bearing slates in the Ogcheon sequence were carried out to examine the lithological and structural controls, and geochemical environment in the uranium deposition in the sequence. And the study was extended to the coal-bearing formation (Jangseong Series-Permian) to compare the geochemical and sedimentologic aspects of uranium chemistry between Ogcheon and Hambaegsan areas. The results obtained are as follows: 1. The uranium mineralization occurs in the carbonaceous black slates of the middle to lower Guryongsan formation and its equivalents in the Ogcheon sequence. In general, two or three uranium-bearing carbonaceous beds are found with about 1 to 1.5km stratigraphic interval and they extend from Chungju to Jinsan for 90km in distance, with intermittent igneous intrusions and structural Jisturbances. Average thickness of the beds ranges from 20 to 1,500m. 2. These carbonaceous slate beds were folded by a strong $F_1$-fold and were refolded by subsequent $F_1$-fold, nearly co-axial with the $F_1$, resulting in a repeated occurrence of similar slate. The carbonaceous beds were swelled in hing zones and were shrinked or thined out in limb by the these foldings. Minor faulting and brecciation of the carbonaceous beds were followed causing metamorphism of these beds and secondary migration and alteration of uranium minerals and their close associations. 3. Uranium-rich zones with high radioactive anomalies are found in Chungju, Deogpyong-Yongyuri, MiwonBoun, Daejeon-Geumsan areas in the range of 500~3,700 cps (corresponds to 0.017~0.087%U). These zones continue along strike of the beds for several tens to a few hundred meters but also discontinue with swelling and pinches at places that should be analogously developed toward underground in their vertical extentions. The drilling surveyings in those area, more than 120 holes, indicate that the depth-frequency to uranium rich bed ranging 40~160 meter is greater. 4. The features that higher radioactive anomalies occur particularly from the carbonaceous beds among the argillaceous lithologic units, are well demonstrated on the cross sections of the lithology and radioactive values of the major uranium deposits in the Ogcheon zone. However, one anomalous radioactive zone is found in a l:ornfels bed in Samgoe, near Daejeon city. This is interpreted as a thermal metamorphic effect by which original uranium contents in the underlying black slate were migrated into the hornfels bed. 5. Principal minerals of the uranium-bearing black slates are quartz, sericite, biotite and chlorite, and as to chemical composition of the black slates, $Al_2O_3$ contents appear to be much lower than the average values by its clarke suggesting that the Changri basin has rather proximal to its source area. 6. The uranium-bearing carbonaceous beds contain minor amounts of phosphorite minerals, pyrite, pyrrhotite and other sulfides but not contain iron oxides. Vanadium. Molybdenum, Barium, Nickel, Zirconium, Lead, Cromium and fixed Carbon, and some other heavy metals appear to be positive by correlative with uranium in their concentrations, suggesting a possibility of their genetic relationships. The estimated pH and Eh of the slate suggests an euxenic marine to organic-rich saline water environment during uranium was deposited in the middle part of Ogcheon zone. 7. The Carboniferous shale of Jangseong Series(Sadong Series) of Permian in Hambaegsan area having low radioactivity and in fluvial to beach deposits is entirely different in geochemical property and depositional environment from the middle part of Ogcheon zone, so-called "Pibanryong-Type Ogcheon Zone". 8. Synthesizing various data obtained by several aspects of research on uranium mineralization in the studied sequence, it is concluded that the processes of uranium deposition were incorporated with rich organic precipitation by which soluble uranyl ions, $U{_2}^{+{+}}$ were organochemically complexed and carried down to the pre-Ogcheon sea bottoms formed in transitional environment, from Red Sea type basin to Black Sea type basin. Decomposition of the organic matter under reducing conditions to hydrogen sulfide, which reduced the $UO{_2}^{+2}$ ions to the insoluble uranium dioxide($UO_2$), on the other side the heavy metals are precipitated as sulfides. 9. The EPMA study on the identification of uraninite and others and the genetic interpretation of uranium bearing slates by isotopic values of this work are given separately by Yun, S. in 1984.

• Korea journal of population studies
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• v.13 no.2
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• pp.1-18
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• 1990

This is a study which attempt to analyze changing patierns of economic active popu-lation, t o estimato- future patterns, and exa- mine vartons problems arises by changing c ire u mst ances of t he labor force market in- clunging soici al, economic ic, heathl th and demoi-graph ic aspects. We have constructed series of wotking life table which are useful in syt uiolyioig the lirocess of growth and structural change of labor force. Work i ng life tables represent ihie life eyele of econrmic' activity in hi ypothetical cohorts, that is. gen-erat i on of men Sn bject at eat' b period ot f their lives th given ra to's o mor tali it y and of par-- tici pation in economic activities. The tabloes prot' ide measorues of the alvet'age he ng t able of economically aeti \- e life. and agespecific rates of en trannee' into and retirement from the hahn' force. In const routing working life tables, age-specific activity rates and life tabole popula- titoto which represents contemporary condi-tions of moortality in Korea au'e the basic' maltoerials. We have derived the age-specific rates foorm economically active population survey, whoich were conducted by the Bureau of Statistics, Economic Planning Borard of the Korean government. Working life tables are constructed for men wtable these materi- als in the year of 1970, 1980 and 1988 by a modified Wolfbein-Wool's method. Some of the findings may be summerized as follow : 1) A central part of constructing working life table is calculation of stationary' economic active population, which represents the number of men in the stationtary population extoected to be in the labor force at each age group in the life span. The stationary economic active population by age have generally a universal pattern, where they rise sharply in the early twenties, approach its' peak in the thirties decline thereafter. at first graolually and then more rapidly at an advanced age. Korean men show the same general pa ttern of age distribution of stationary eco-- nomic active population with sharp increase hegining from the age interval of 20 to 24, reaching to maximum level at older age. The population. however, presumably, increased substantially due to increaseing school atte endance rates. Another difference exiSts in the youngest age groups, that is the activity rate in the year of 1988 is lower than that of Japan. The table shows an analysis of changes in the age distrihution of labor force between 1970, 1980 and 1988. 2) It was shown an analysis of changes in the age distribution and cause of separation from labor force. The entrance rate to labor force has increased from 18~\5 persons to 299 persons per 1000 head of stationary population between that of 1980 than that of 1988 for Korean men in 20~24 age group. The entrace rate to labor force shows a rapid entrance appearance concentrated on the 15~24 age group. The separation rate from labor force by retirment in Korea in the year of 1988 shows a great difference of the about four times as much as that of Japan. 3) The functions of table illustrate the patterns of working life of males in Korea in 1970, 1980 and 1988. The average remaining number of economically active years, e at age 15 in 1988 is 46.39 which is 2.12 years of increase compared with that of at age 15 in 1970,1980 and 1988 are 43.90,44.27 and 46.39 respectively, showing steadily increase dur- ing the past double decade the increase in the length of economically active life various age may be considered to have come both from extention of general life expectancy and from increasing entrance rate to economic activity in high age that of working is far greater in 1988 than that of 1980. The gaps between expectation of life and average remaining years of economically active widened due to rapid improvement of mortality level in Ko- rea. This observation together with the population pressure by the appearance of a group of younger population implies that constant increase of economically inactive population among older age group.

• The Journal of the Petrological Society of Korea
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• v.15 no.1 s.43
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• pp.25-38
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• 2006

Metamophic rocks of Samcheog area, northeastern Yeongnam massif, was studied petrochemically. This area includes Precambrian Hosanri Formation (schists and gneisses) and granitoid (Icheon granitic gneiss, leucocratic granite and Hongjesa granite), Cambrian sedimentary rocks, and Cretaceous sedimentary and acidic volcanic rocks. Hosanri formation is composed of quartz+plagioclase+K-feldspar+biotite+muscovite+granet${\pm}$cordierite${\pm}$sillimanite. Mineral assemblage of biotite granitic gneiss, which is massive granodioritic rock with weak foliation, is similar to Hosanri formation. According to mineral assemblages, metamorphic rocks of studied area can be divided into two metamorphic zones (garnet and sillimanite zones). From Icheonri area, major, trace and rare earth element data of biotite granitic gneiss and luecocratic granite suggest that source rock is politic rocks of Hosanri formation and source magma was formed by anatexis and experienced fractionation of plagioclase. Trace element diagram show collisional environment such as syn-collisional, volcanic arc granite. Orientation of faults in study area have three maximum concentrations, $N54^{\circ}\;W/77^{\circ}\;SW,\;N49^{\circ}\;W/81^{\circ}\;NE\;and\;N10^{\circ}\;W/38^{\circ}\;NE$. Structure analysis suggests that faults in study area ware formed by uplift and compression. Faulting age is guessed after Tertiary because some shear joints is developed in dikes to intrusive Cretaceous acidic volcanic rock. Hosanri formation and Icheon granitic gneiss had experienced similar deformation history because they have maximum concentration to foliations, $N89^{\circ}\;E/55^{\circ}\;SE\;and\;N80^{\circ}\;E/45^{\circ}\;SE$, respectively.

• Journal of Periodontal and Implant Science
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• v.36 no.2
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• pp.345-359
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• 2006

Loss of maxillary molar teeth leads to rapid loss of crestal bone and inferior expansion of the maxillary sinus floor (secondary pneumatization). Rehabilitation of the site with osseointegrated dental implants often represents a clinical challenge because of the insufficient bone volume resulted from this phenomenon. Boyne & James proposed the classic procedure for maxillary sinus floor elevation entails preparation of a trap door including the Schneiderian membrane in the lateral sinus wall. Summers proposed another non-invasive method using a set of osteotome and the osteotome sinus floor elevation (OSFE) was proposed for implant sites with at least 5-6mm of bone between the alveolar crest and the maxillary sinus floor. The change of grafted material in maxillary sinus is important for implant survival and the evaluation of graft height after maxillary sinus floor elevation is composed of histologic evaluation and radiomorphometric evaluation. The aim of the present study was radiographically evaluate the graft height change after maxillary sinus floor elevation and the influence of the graft material type in height change and the bone remodeling of grafts in sinus. A total of 59 patients (28 in lateral approach and 31 in crestal approach) who underwent maxillary sinus floor elevation composed of lateral approach and crestal approach were radiographically followed for up to about 48 months. Change in sinusgraft height were calculated with respect to implant length (IL) and grafted sinus height(BL). It was evaluated the change of the graft height according to time, the influence of the approach technique (staged approach and simultaneous approach) in lateral approach to change of the graft height, and the influence of the type of graft materials to change of the graft height. Patients were divided into three class based on the height of the grafted sinus floor relative to the implant apex and evaluated the proportion change of that class (Class I, in which the grafted sinus floor was above the implant apex; Class II, in which the implant apex was level with the grafted sinus floor; and Class III, in which the grafted sinus floor was below the implant apex). And it was evaluated th bone remodeling in sinus during 12 months using SGRl(by $Br\ddot{a}gger$ et al). The result was like that; Sinus graft height decreased significantly in both lateral approach and crestal approach in first 12 months (p$MBCP^{TM}$ had minimum height loss. Class III and Class II was increased by time in both lateral and crestal approach and Class I was decreased by time. SGRI was increased statistically significantly from baseline to 3 months and 3 months(p<0.05) to 12 months(p$ICB^{(R)}$ single use, more reduction of sinusgraft height was appeared. Therefore we speculated that the mixture of graft materials is preferable as a reduction of graft materials. Increasing of the SGRI as time goes by explains the stability of implant, but additional histologic or computed tomographic study will be needed for accurate conclusion. From the radiographic evaluation, we come to know that placement of dental implant with sinus floor elevation is an effective procedure in atrophic maxillary reconstruction.

• 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.