• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.13 no.1
• /
• pp.1-5
• /
• 1977

A series of echo-sounding and current measurements as well as the drogue and the drift bottle experiments were carried out in Asan Bay since November 1974. Several sand bars or sand flats covered by silts were developed at ebb tide in the bay. Sand waves and sand ripples were seen on the surface of the sand bars, around which sea channels of 8~ 12 meters in depth are formed. The main stream axis of the flood current which is separated into east and west branch flows southward. A cyclonic and an anticyclonic eddy are developed at the early stage of flood tide. They are transformed into a clockwise eddy before the slack water. The maximum tidal current speed observed was 3.1 ~ 3.2 knots at the entrance of the bay, while it was 1.O ~ 2.8 knots in the bay. The location of the main stream axis of the tidal current coincides well with the sea channel. A salt wedge was observed at the estuary of the Sabgyo-cheon River.

• Clinics in Shoulder and Elbow
• /
• v.8 no.2
• /
• pp.117-121
• /
• 2005

A secure slip knot is very important in the arthroscopic surgery of the shoulder joint. The new 'Hallym Slider', developed by the first author(KCN), has the properties of being a simple sliding and one-way locking knot. This technique can be performed alone without an assistant and has no accidental premature locking during the knot tying. The initial slip knot determines the adequacy of tissue approximation and consequent healing. The 'Hallym Slider' has excellent initial holding capacity, maintaining tension on soft tissue while additional half-hitches are being tied. It locks readily, it takes less time to tie than numerous square knots, and it is not as bulky as other knots. Therefore, we introduce this new sliding and one-way locking knot during the arthroscpic surgery of shoulder.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.5
• /
• pp.83-86
• /
• 1985

An alternative technique (or the numerical solution of Fredholm integral equations of second kind is presented. The approximate solution is obtained by fitting the data in mixed form at knots in the region of the problem. To decrease the error in the numerical solution, cubic B-spline functions which are twice continuously differentiable at knots are employed as basis function. For a given example, the results of this technique are compared with those of Moment method employing pulse functions for basis function and delta functions for test function and found to br in good agreement.

• Journal of The Korean Astronomical Society
• /
• v.23 no.1
• /
• pp.31-42
• /
• 1990

Fine structures of a quiescent prominence are studied by analyzing high resolution H alpha filtergrams and H alpha line spectra observed at the Hida Observatory of Kyoto University. We have found two kinds of downward motions in the prominence. One of them is a movement with a constant acceleration below the solar gravity(${\simeq}1/4g_s$) and the other with an uniform velocity(${\simeq}16Km/s$). The average life time and the size of prominence knots are estimated to be about 7 minutes and 4000Km, respectively. Spatial and brightness distribution of knots are also presented in this paper. With the analytical solutions derived from magnetostatic equilibrium in the prominence, we have examined the filamentary structure based on the Kippenhahn-Schluter model. Sag angles of the magnetic fields supporting the prominence matter are predicted from the observed density profile.

• Journal of the Korean Institute of Navigation
• /
• v.10 no.2
• /
• pp.1-10
• /
• 1986

For the purpose of estimation of navigational method and ability about fishing raft, we have practical navigation of her from Chujado on Oct, 7 to Maryang-ri , Kangjin-kun, Jeonranman-do on Oct.10. The results obtained are as follow : 1. Ancient navigation of her is thought to over to an isolated island in the vicinity with a good informations and experiences. 2. Speed of her in outward voyage is 1.34 knots, but is varied with structure and shape of her and ability of fishing raftman. 3. The lee way(U) of her with sail of hight 2.5m and breadth about 1.2m according to windspeed(W) is U=$0.038{\times}W$ 4. We could estimate to take only three days to go over from Chujado to Maryang-ri, Kangjin-kun. Jeonranam-do by her with sail, and make a voyage total 55 miles for thirty-four hours and ten minutes i, e, mean speed is 1.6knots resulty.

• Proceeding of EDISON Challenge
• /
• 2016.03a
• /
• pp.588-592
• /
• 2016

선박의 최적 운항 자세를 찾기 위해 자유 수면을 포함한 저항 해석을 수행할 경우 많은 격자를 이용한 비정상 해석으로 인해 계산 시간이 오래 소요되는 단점이 있다. 본 연구에서는 이를 개선하여 이중 모형을 이용한 정상 해석을 통해 보다 효율적으로 선박의 최적 운항 자세를 도출하는 방법을 연구하였다. KCS를 대상선으로 선정하여 설계속도(24knots)와 저속(15knots)인 경우에 대하여 평형 상태 및 선수/선미 트림 상태에서 이중 모형 수치해석을 수행하고 기존의 연구결과와 비교하였다. 그 결과 자유수면 유무와 속도에 상관없이 선체 자세에 따른 저항 값은 동일한 경향을 갖는 것을 확인하였다. 하지만 저속일 경우 트림조건에 따른 저항의 변화의 폭에서 차이를 보였으며, 이는 압력저항에 기인한 것이다. 따라서 이중 모형을 이용한 저항 해석은 압력저항의 변동이 큰 경우에는 적용되기 어렵다는 한계점이 있다. 하지만 마찰 저항이 주요한 경우에 적용되어 계산효율을 획기적으로 높일 수 있으며, 정성적인 경향을 제시할 수 있는 타당한 방법이라 사료된다.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.6 no.1
• /
• pp.21-29
• /
• 1998

The purpose of the present paper is to determine the time required and error tolerance limits for flight data computation. The results of statistical analysis showed that the calculator side computation required about 50 seconds for each question and wind side computation needed about 115 seconds for each question. In case of error tolerance limits, it was found that the error tolerance limit for altitude computation war 90 feet and two knots of interval was recommanded for the speed computation in calculator side, and one degree of interval for heading computation and five knots interval for speed computation in wind side.

• Kyungpook Mathematical Journal
• /
• v.57 no.1
• /
• pp.145-161
• /
• 2017

If a virtual knot diagram can be transformed to another virtual one by a finite sequence of crossing changes, Reidemeister moves and virtual moves then the two virtual knot diagrams are said to be homotopic. There are infinitely many homotopy classes of virtual knot diagrams. We give necessary conditions by using polynomial invariants of virtual knots for two virtual knots to be homotopic. For a sequence S of crossing changes, Reidemeister moves and virtual moves between two homotopic virtual knot diagrams, we give a lower bound for the number of crossing changes in S by using the affine index polynomial introduced in [13]. In [10], the first author gave the q-polynomial of a virtual knot diagram to find Reidemeister moves of virtually isotopic virtual knot diagrams. We find how to apply Reidemeister moves by using the q-polynomial to show homotopy of two virtual knot diagrams.

• Journal of the Korean Wood Science and Technology
• /
• v.31 no.6
• /
• pp.45-54
• /
• 2003

The density and strength of wood is affected by degradations and defects, such as voids and knots. Old wooden structures such as traditional cultural properties have been deteriorated by these types of defects. They were evaluated by a visual observation that is difficult to evaluate the inner deterioration in structures. In this study, three nondestructive testing techniques were investigated to detect the wooden structural members. Ultrasonic stress wave tests, drilling resistance tests and visual inspections were used to examine the structural wood members. Patterns of Resistograph using by drilling resistance tests could indicate the features of internal wood such as voids, knots, decay, fungi, and so on. The technique just like as ultrasonic stress wave tests, however, difficult to detect exactly area where small amounts of internal deterioration in logs are. In spite of results of ultrasonic stress wave test, the internal deterioration of wooden structural members could be evaluated by the relationship between ultrasonic stress wave tests and drilling resistance tests.

• Kyungpook Mathematical Journal
• /
• v.64 no.2
• /
• pp.311-335
• /
• 2024

The fundamental quandle is a powerful invariant of knots, links and spatial graphs, but it is often difficult to determine whether two quandles are isomorphic. One approach is to look at quotients of the quandle, such as the n-quandle defined by Joyce [8]; in particular, Hoste and Shanahan [5] classified the knots and links with finite n-quandles. Mellor and Smith [12] introduced the N-quandle of a link as a generalization of Joyce's n-quandle, and proposed a classification of the links with finite N-quandles. We generalize the N-quandle to spatial graphs, and investigate which spatial graphs have finite N-quandles. We prove basic results about N-quandles for spatial graphs, and conjecture a classification of spatial graphs with finite N-quandles, extending the conjecture for links in [12]. We verify the conjecture in several cases, and also present a possible counterexample.